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THEBlb A LIBRARY Michigan State U' "ty This is to certify that the thesis entitled THE BATS OF SOUTHERN LOWER MICHIGAN - presented by Allen Kurta has been accepted towards fulfillment of the requirements for M. S . degree in Zoologx quor professor 07639 Ill/Ill "~ 3 1293 10466 4895 ." ll/I/l/l/Il/l/II/l/I/ll/lI/ll/I/IlllllIl/lIlI/l/I/lllll LT.“ < 1 etc A 4‘ 4 3:4— L. OVERDUE FIQES: l 25¢ per day per item RETURNING LIBRARY MATERIALS: 4 \ Place in book return to remove charge from circulation records ~ 2 mzfimwsg'fi ! 0 “CU—33‘ gwfi - OCT 2 5 1993 "070915 .«l THE BATS OF SOUTHERN LOWER MICHIGAN By Allen Kurta A THESIS Submitted to Michigan State University in partial fulfillment of the requirements for the degree of MASTER OF SCIENCE Department of Zoology 1980 A .. AA «my V) \l \\ EAJJ 1., ABSTRACT A two-year survey of bat populations in southern Lower Michigan began in May 1978 and lasted until March 1980. Data was obtained through mist-netting, visiting known bat roosts, examining museum collections and utilizing bats submitted to the Michigan Department of Public Health for rabies testing. The big brown bat (Eptesicus fuscus) was the most common colonial chiropteran and the red bat (Lasiurus borealis) was the most abundant solitary tree- dweller. Most information obtained during the study pertained to the big brown bat. Parturition in E. fuscus occurred between 3 June and 3 July. Litter size is generally two. Houses and barns were the structures most commonly used as maternity roosts. Roosting sites within barns varied, but, in most houses, the bats were found inside the walls or in an eave. The point where a chimney intersected the roof- line was the most common entrance to house roosts. Average colony size was 51.6 animals, ranging from 5 to 150 bats. ACKNOWLEDGEMENTS I wish to thank the members of my committee for their advice and encouragement: Rollin H. Baker (Chairman), Donald L. Beaver, Glenn R. Duderar and Sylvia Taylor. Mary E. Stewart assisted with the field work and manuscript preparation. The project was supported by federal aid, the United States Fish and Wildlife Service and the Michigan Department of Natural Resources cooperating through the provisions of the Federal Endangered Species Act of 1973 and the Michigan Endangered Species Act of 1974. In addition, I would like to thank Benjamin Bohnsack for providing access to the colony at Hardy Church. Mr. and Mrs. Flannagan permitted me to work at Bear Cave. Michael Huntzinger from the Michigan Department of Public Health, Virology Division, was extremely helpfulixlobtain- ing information on rabies submissions. Wayne H. Davis and James B. Cope supplied unpublished data concerning their banding returns. Christopher D. Burnett provided the age predictive formulae for the little brown bat and the big brown bat. John Lerg, Andreas Ricther, Kevin L. Boyd, Daniel E. Bennack, Nancy Gosling, Judy DeJaegher, Laurena Jenkins and Robert Bloye assisted with various aspects of the study. ii iii The following curators allowed me to examine specimens under their care or provided information concerning their collections: Richard Brewer, Western Michigan University; R. C. Fleming, Olivet College; Gail Gorton, Central Michigan University; Robert W. Husband, Adrian College; Philip Myers, University of Michigan; William Prychodko, Wayne State University; William C. Scharf, Northwestern Michigan College; Robert C. Stones, Michigan Technological University; and Asa Thoresen, Andrews University. TABLE OF CONTENTS List of Tables. List of Figures PART I. RELATIVE ABUNDANCE AND SPECIES ACCOUNTS INTRODUCTION. MATERIALS AND METHODS . Date and Location of Study Area . Standard Data . . Reproductive Condition and Age. Physical Data . Roosts. . Hardy Church. Mist— —Netting. Bear Cave . . . Bats Submitted for Rabies Testing . Museum Survey . . . . . Geographical Distribution . Statistical Procedures. RELATIVE ABUNDANCE. Results Discussion. SPECIES ACCOUNTS. Big Brown Bat, Eptesicus fuscus (Palisot de Beauvois) Tree Roost of a Maternity Colony. Age of Building Roosts. . Species Associates at Nursery Roosts. Location of Exits at Maternity Colonies Time of Evening Flight. . Nursery Roost Population Size . . . Pregnancy, Parturition and Lactation. Reproduction at Hardy Church. . . Population Size at Hardy Church . iv Page vii . viii Litter Size and Pregnancy Rates Sex Ratios. . Seasonal Activity . . . Geographic Distribution . Little Brown Bat, Myotis lucifugus (Le Conte) Reproduction. . . . . . . . . . Bear Cave . . . Seasonal Activity . . Geographic Distribution . Indiana Bat, Myotis sodalis Miller and Allen . Pre-l978 Records. . . . . . . . . . Mist- -Netting Captures Seasonal Activity . . . Geographic Distribution . Eastern Long- -Eared Bat, Myotis keenii (Merriam) Summer Captures and Reproduct1ve Data . Bear Cave . . . Seasonal Activity . . Geographic Distribution . Hoary Bat, Lasiurus cinereus (Palisot de Beauvois) . Summer Captures and Reproductive Data . Seasonal Activity . . . . . Geographic Distribution . Red Bat, Lasiurus borealis (Mueller). Summer Captures and Reproductive Data . Sex Ratio . . . Seasonal Activity . . Geographic Distribution . Silver- Haried Bat, Lasionycteris noctivagans (Le Conte). . . Summer Captures and Reproductive Data . Parturition and Description of Young Silver- Haired Bats. . . Seasonal Activity . . Geographic Distribution . Evening Bat, Nycticeius humeralis (Rafinesque). Eastern Pipistrelle, Pipistrellus subflavus (F. Cuvier) 92 92 96 102 102 107 vi Page PART II. FLIGHT PATTERNS OF MYOTIS LUCIFUGUS AND EPTESICUS FUSCUS INTRODUCTION. . . . . . . . . . . . . . . . . . . . . llO MATERIALS AND METHODS . . . . . . . . . . . . . . . . 112 RESULTS . . . . . . . . . . . . . . . . . . . . . . . 114 DISCUSSION. . . . . . . . . . . . . . . . . . . . . . 128 APPENDIX A. . . . . . . . . . . . . . . . . . . . . . 131 APPENDIX B. . . . . . . . . . . . . . . . . . . . . . 134 LITERATURE CITED. . . . . . . . . . . . . . . . . . . 137 Table Table Table Table Table Table Table Table Table LIST OF TABLES Age-predictive formulae for Eptesicus fuscus and Myotis lucifugus, based on forearm length. Bats submitted for rabies testing to the MDPH from the southern four tiers of counties in Lower Michigan. Mist-netting results from 1978 and 1979 Number of non-Thornapple River sites at which each species was netted in 1978 and 1979. Bats submitted for rabies testing in Michigan from N and S of the 44th parallel. . . . . . . . . Michigan recoveries of Myotis sodalis banded in Kentucky. Fetal and immature Lasiurus borealis obtained from Washtenaw County and now in the collection of the University of Michigan Museum of Zoology. Mist-netting localities Location of Eptesicus fuscus nursery roosts. vii Page 22 23 24 6O 70 90 131 134 Figure Figure Figure Figure Figure Figure Figure Figure Figure Figure Figure Figure Figure 10. 11. 12. 13. LIST OF FIGURES The study area. Mist-netting localities in southern Lower Michigan. Mist- -netting along the Thornapple River . . . . . . . . . Cave or cave-like hibernacula close to the study area. Location of Eptesicus fuscus maternity roosts. Weight change of adult female E. fuscus at Hardy Church . . . . . . . . Weight change in a single E. fuscus female. Change in population size at Hardy Church. Number of big brown bats submitted for rabies testing from the southern four tiers of Michigan counties by month . Counties from which Eptesicus fuscus has been reported . Nightly activity of M otis at Bear Cave in September 1978 and 1979. . . . Banding recoveries of Myotis lucifugus within 25 km of southern Lower Michigan from Fisher (1955) and J. B. Cope (personal communication). . Counties from which Myotis lucifugus has been reported . . . . . viii Page 14 16 28 32 43 46 48 51 59 65 69 72 Figure Figure Figure Figure Figure Figure Figure Figure Figure Figure Figure Figure Figure Figure 14. 15. 16. 17. 18. 19. 20. 21. 22. 23. 24. 25. 26. 27. ix Capture localities of Myotis sodalis in Michigan . Counties from which Myotis keenii has been reported . from which Lasiurus cinereus reported . Counties has been from.which Lasiurus borealis reported . Counties has been Monthly records of Lasionycteris noctivagans taken in southern Lower Michigan. Counties from which Lasionycteris noctivagans has been reported . Records of Nycticeius humeralis in Michigan. Records of Pipistrellus subflavus in Michigan. . . Capture positions of 21 Myotis lucifugus obtained on nine nights Eétween 24 June and 24 August 1979. Capture positions of 11 Myotis lucifugus obtained on three nightsvbetween 6 and 18 June 1979. Capture positions of 51 Eptesicus fuscus obtained on nine nights Between 24 June and 24 August 1979. Capture positions of 9 Eptesicus fuscus obtained on three nights between 6 and 18 June 1979. Capture positions of 32 adult Eptesicus fuscus obtained on eight nights between 24 June and 12 August 1979. Capture positions of 11 juvenile Eptesicus fuscus obtained on eight nights between 24 June and 12 August 1979. . . . . . . . . . . . . Page 76 84 89 94 101 104 106 109 116 118 120 122 125 127 PART I RELATIVE ABUNDANCE AND SPECIES ACCOUNTS INTRODUCTION Biologists have recorded very little information con- cerning the Chiroptera of Michigan. Before 1978, only two extensive field projects had ever been completed. Hitchcock (1943) began banding little brown bats (Myotis lucifugus) at the University of Michigan Biological Station at Douglas Lake, Cheboygan County, in 1942, and his work was continued the following year by Mohrmann (1943). Data from these two reports contributed to a later, more inten- sive study of homing and roost site selection by Fisher (1955). In the only other major Michigan study, Stones and Fritz (1969) described the annual movements of M, lucifugus- at summer nursery colonies and winter hibernacula in the Keweenaw Peninsula. Additional references to Michigan's flying mammals can be found in a variety of regional surveys (for example, Manville, 1948; Phillips gt 31., 1965; Scharf, 1973; Scharf and Jorae, 1980; Ozoga and Phillips, 1965; Hatt gt a1., 1948; Wood, 1914, 1922a, 1922b). These authors, however, were not primarily concerned with bats and most of the information presented is incidental to that gathered on other terrestrial mammals. Other published accounts pertaining to Michigan bats summarize the rabies problem (Kurta, 1979b), reveal new geographic records (Burt, 1939; Nichols and Stones, 1971; Stones and Haber, 1965) or indicate new seasonal records (Baker, 1969; Bowers gt gl., 1968; Gosling, 1978; Stones and Holyoak, 1970). A number of notes describing different aspects of chiropteran natural history based on Michigan observations are also in print (Cahalane, 1932; Dalby, 1969; Davis, 1964; Dice, 1927; Drake, 1957; Denys, 1972; Kurta, 1979a, 1980a, 1980b; Kurta and Matson, 1980; Scharf and Stewart, 1980; Stones and Branick, 1969; Stones and Oldenburg, 1967; Stuewer, 1948). The status of Michigan bats is not well known. Only four species appear to be common; these are the big brown bat (Eptesicus fuscus), the little brown bat (Myotis lucifugus), the eastern long-eared bat (Myotis keenii) and the red bat (Lasiurus borealis). Eptesicus fuscus and M, lucifugus are colonial chiropterans that usually locate their maternity roosts in buildings (Barbour and Davis, 1969). Myotis keenii is also colonial. The few known nursery colonies of the long-eared bat have been found in both trees and buildings (Fitch and Shump, 1979). Lasiurus borealis is a solitary species that spends the day hanging, from tree branches (Mumford, 1973). Two other solitary tree-dwelling chiropterans occur in Michigan. These are the silver-haired bat (Lasionycteris noctivggans) and the hoary bat (Lasiurus cinereus). The Endangered and Threatened Species Committee (1979) of the Michigan Department of Natural Resources lists both species as Rare. This classification, although possibly warranted, is not the result of documented field work. There are three other colonial bats that are known from Michigan. One of these, the Indiana bat (Myotis sodalis), is presently included on the Federal List of Endangered Species (LeraznuiFortune, 1979). Before 1978, only nine records of this mammal were known for the entire state. All Indiana bat nursery roosts have been found in hollow trees or underneath loose bark (Humphrey gt gt., 1977). The last two species are the evening bat (Nycticeius humeralis) and the eastern pipistrelle (Pipistrellus subflavus). At the start of my study, there were only three known records of N. humeralis and only three reports of P. subflavus for the state of Michigan. Evening bats form their maternity colonies in trees or in man-made structures (Watkins, 1972), while the few known summer colonies of the eastern pipistrelle were located in build- ings (Barbour and Davis, 1969). It is the purpose of this study to investigate the reproduction, relative abudnace, geographic distribution and seasonal status of a neglected group of Michigan mam- mals. MATERIALS AND METHODS Date and Location of Study Area The study area consisted of the southern four tiers of counties in the Lower Peninsula of Michigan (Figure 1). Surface features are mainly the result of Pleistocene glaciation with the remnants of till plains, moraines and glacial lake beds predominating (Dorr and Eschman, 1970). Small streams, ponds and lakes are numerous. The region has low relief with a maximum elevation of only about 250 m. Much of the land consists of flat to rolling farmland. The project began in May 1978 and continued to March 1980. Almost all field work took place during the warm- weather months of May through September of each year. Standard Data Bats were weighed using a Pesola spring balance with 0.5 g gradations. In order to minimize movement, live animals were confined to a small plastic vial with the known weight of the vial then being subtracted to obtain the actual weight of the bat. Standard linear measurements were made with a plastic millimeter rule. In addition to these measurements, the forearm length, as described by Patterson and Davis (1968), was also determined, using a Figure 1. The study area. Solid circles indicate counties that were included as part of the study area. .. w P w u u m . d J 01 < 1 d 0 . 0 ' .1 L $9 7....-- m e03. . it? n. _ I. . M AW. . .Q 1“ m 1....-- 4 E . w .124. 4 ..... 1. - .w _. L o x __ o ,- e .. _ .1 J :_ . . . _ _ M Tin, _& .I ..... L . _ . . — .a .I _w m _m - 1 -fi A. —.4 n t 1 u . _n a _ _.. 1.. h .m _ O «xi-l1 N ma-Li-L--.x .. In: 1.”. . L . m u. a . L . w L w . .- _ . .LN .. w .. .. . "L .. ..N . T1»--. m m- .-T i.--1.m m 7:. 1L.“ 0 x o T--- .“ .. _ _m r _ _m _u .. __ L. .. . T-. _. . l. -l_.0 -. . a .m _.u T!I|.Jm Id J m _ . Il—l. ll.“ . Fllli . .74“.-- -- - ..m a u. - _ a .w o m . ..._ u . _ -. . - at. - .i m..." _ m ._...--- _... n. .. o w _. _w o . . _._.......m m... _. _.Liiu . 72...--- ..w _- -- . . _ l. _ .1. “m .2 1.. -- .1» o _r.- a e .m e .- x. .. “1.3-. ._ u. _.u _ ..i. 0 Q0 . .m L. A-..” W . u. "m o "a. . .1. 71 a 1“ -- .- 0p. ‘ . 59.6...wa .1. 041m «1;» m-.x u ”SM Kl l mrrx millimeter rule in 1978 and dial calipers in 1979. Before June 1979, bats were not marked for later recognition; after that time, all animals were punch-marked (Bonaccorso and Smythe, 1972) before release. Reptoductive Condition and Age Female reproductive condition was determined following the technique of Kunz (1971, 1973). A female was described as lactating if milk could be expressed from a nipple and the mammary tissue appeared white beneath the skin. If no milk could be obtained, or if the mammary tissue appeared pink or if the nipples were not pendulous, the animal was considered post-lactating. Pregnancy was determined by palpation. This method could detect only females in the advanced stages of pregnancy. Early in the season, all bats could be separated into adult or juvenile categories based on the degree of phalangeal ossification. As development proceeds, however, and the juveniles approach adult size, it is difficult to distinguish between the two groups. In order to avoid errors, any comparisons made between immatures and adults will be restricted to animals captured before the arbitrary cut-off date of 16 August. Burnett and Kunz (1979; C. D. Burnett, personal communication) have demonstrated that the increase in fore- arm length of young little brown bats is linear up through 11 days of age and that this growth rate apparently does not vary between roosts. Using regression analysis, they have developed a predictive formula that can be used to estimate the age of immature E. lucifugus (Table 1). A similar predictive formula is also available for big brown bats (Table 1). I have used the two formulae to estimate the birth dates of all appropriately-sized E. fuscus and E. lucifugus. I wish to emphasize that these dates are only estimates and that the possibility of regional or local differences in growth rate may exist. Table 1. Age-predictive formulae for Eptesicus fuscus and Myotis lucifugus, based on forearm length (Burnett and Kunz, 1979; C. D. Burnett, personal communication). FA = forearm length Myotis lucifugus Eptesicus fuscus Age = Age = FormUIa -8.87 + 0.62 x FA -1o.4 + 0.68 x FA Range of 95% Confidence t 1.22 to 1.23 days i 1.63 to 1.79 days Intervals Valid Age Range 1 to 11 days 1 to 15 days Valid Forearm Length Range 15.9 to 32.0 mm 16.8 to 37.4 mm Physical Data Relative humidity was measured with a Bacharach sling psychrometer. Ambient temperatures were obtained from the dry bulb of the psychrometer or from a Yellow Springs Instruments telethermometer (Model #43A). There were no apparent differences between the two instruments at 11 and 23°C. Roosts Bat roosts were located with the help of the general public. Over 200 letters of inquiry were sent to public , school teachers, nature centers and appropriate government offices. A "Bats Wanted" poster was placed in grocery stores, libraries, feed mills and other prominent loca- tions. In addition, various local newspapers and statewide magazines provided extensive publicity. The species of bat utilizing a building roost was determined by sight identification or by using the obvious difference in fecal pellet size between Eptesicus and Myotis. Bats were captured at roosts with hand-nets, 25-cm forceps or by stretching mist nets near exit points. Pre- ferred entrances were identified by personally observing evening flights or by detecting the urine and body oil stains, as well as droppings, that accumulated near a bat's exit (see Figures 67 and 123 in Barbour and Davis, 1969). Population estimates were made by counting the animals as they emerged from the roost between sundown and one hour after sunset. Visual observations and the use of an ultra- sonic sound detector (QMC Mini, Queen Mary College, London) indicated that most, if not all, bats had left by one hour after sundown. All counts were made with ambient 10 temperatures at sundown above 12°C; most nights were above 15°C. Cloud cover and moonlight were variable, but no precipitation was recorded on any night. Flight counts are considered to be the most accurate means of estimating colony size (O'Farrell and Studier, 1975; Humphrey, 1971). Hardy Church Most roosts were only visited once. Extensive obser- vations of a single big brown bat maternity colony, how— ever, were made during 1979. This colony resided in the Hardy United Methodist Church, located approximately 7.5 km E Howell, Livingston County (N15). The church was visited at about weekly intervals between 3 April and 16 September 1979. The bats at Hardy Church spent most of the daylight hours within an eave at the rear of the church. Near sun- down, they would fly about 14 m through the 3.4 m-high attic and up into a small tower at the front of the build- ing. Small openings at the roofline of the tower, particularly at the NE and SE corners, were used for enter- ing and exiting. Most bats were captured at the church by stringing a short section of mist net inside the attic and trapping the bats as they attempted to fly by in the evening. When no humans were in the attic, population estimates were obtained by direct flight counts, as at the other roosts. During most visits to Hardy, however, I was in the 11 attic monitoring the net from about 0.5 hr before sundown until one hr after sunset. Population size on these days was estimated by counting the number of volant individuals caught in the attic and adding this number to the flight count made by an assistant. Mist-Netting Mist nets (Bleitz Wildlife Foundation, Hollywood, California) were made of braided nylon and had a 6.0-cm mesh. Individual nets were about 2.13 m in height and either 9.1 or 12.8 m in length. A variety of netting systems were employed. Each system consisted of from one to four single nets joined together and placed one above the other. A double net system (two—tiered), therefore, had an effective height of about 4.3 m; three nets joined together (three-tiered) went up 6.4 m, while a four-tiered system reached just over 8.5 m in height. Standard aluminum mist-netting poles were used with single and two-tiered systems. Larger systems, however, required the use of an appropriately-sized pole consisting of three sections of aluminum electrical conduit (1.9 cm diameter). Smaller pieces of conduit were placed inside, and larger sections were added to the outside of the main pole in order to increase rigidity. When netting, one side of the net was supported by a rope and pulley attached to the pole, while the other side utilized a rope thrown over a convenient tree limb. 12 In 1978, from one to five single nets or a two-tiered system and from zero to three single nets were erected each night. A single three-tiered system was used on 16 September 1978. With the exception of a two—tiered net utilized on 7 May, all netting in 1979 was performed with three- and four-tiered netting systems. All nets set up on any given night were within 0.4 km of each other. All nets set up within 0.4 km of each other on the same or suc- ceeding nights were considered to be at the same geographic location. Thirty-nine sites in 15 different counties (Figure 2; Appendix A) were netted during the study. Throughout the text, netting localities will be referenced to Figure 2 and to Appendix A using the letter N followed by the appro- priate number. In 1978, I mist-netted at 28 localities on 45 different nights between 20 May and 9 November. In 1979, bats were caught on 46 evenings at 26 sites between 7 May and 1 September. Most locations were used only one or two times. One site (N20), however, on the Thornapple River in Eaton County, was netted on eight nights in 1978 and, in 1979, 24 nights were spent at seven different localities (N18-24) along a 9.0 km stretch of that river (Figure 3). Nets were placed across 8 to 15 meter-wide streams that had wooded banks. Netting systems were positioned underneath overhanging tree branches so that as much of the flight corridor as possible was blocked. Actual sites used 13 Figure 2. Mist-netting localities in southern Lower Michigan. Numbers refer to the more exact locations given in Appendix A. 14 3 a». . 1 2:0 - 23:2: .:U OICJ . 3. . O F 'U'l 'h01'0100'00 _ O 2 _ _o o o 2 2.3.5 _ ..Illlti In. _ III-Ill llllll llllll |.—.| Il—I I n, ‘b _ .0: _ _ 3.2. o . g _ _ . . ._ .. _ an . . _ one 5 _ Homm3.n_ 2 _ _ c0022! _ _ Tia-.21. :::::::::: ill—Ill .l.| _.llul _ IN. ON _ _ . _ _ _ m . _ _ l |_. _ 4-I-I-I.:I:.-l-1 _ -l r- Trial .5. . ._ _ a on 15 Figure 3. Mist-netting localities along the Thornapple River. Shaded area is the village of Vermontville, Eaton County. The thick hori- zontal line represents Vermontville Highway. The line running NE-SW is Allegan Road. Circled numbers refer to locations in Appendix A; uncircled numbers indicate sections within a township. 17 depended on ease of access, water depth and the cooperation of land owners. Nets were generally checked at maximum 20-minute intervals for 4 hr after sunset. Rain, high winds or ambient temperatures below 10°C occasionally brought an early end to mist-netting, since these factors tend to severely limit bat activity (Greenhall and Paradiso, 1968; Fenton, 1969, 1970a; Jones, 1965; O'Farrell and Bradley, 1970). All bats obtained in 1978 and early 1979 were examined and then retained in a cloth sack until netting ceased for the night. All bats captured after 6 June 1979 were punch-marked and released immediately after exami- nation. Bear Cave Bear Cave, located 5.5 km N Buchanan, Berrien County, is the only known natural cavern within the study area (Davies, 1955). The cave consists of approximately 150 m of passage in a Pleistocene tufa deposit (Winkler and Van Besien, 1963). The cave is commercialized with human visitors entering through a small store. The bats utilize a small crevice (0.2 by 0.6 m) found toward the eastern end of the cave. This opening is about 2.5 m above the ground and is recessed into a six-meter bluff formed by the tufa. On two nights in September 1978 and five nights in September 1979, I monitored the nightly activity of bats at Bear Cave. Mist nets in 1978 and mist nets and a bat trap 18 (Tuttle, 1979) in 1979 were placed in front of and to either side of the small opening. Nets were checked at a maximum of 20-minute intervals throughout the night; the trap was emptied at the end of each hour. Time of capture, species and sex were noted for each animal captured. Bats Submitted for Rabies Testing In Michigan, most bats suspected of rabies are sub- mitted to the Michigan Department of Public Health (MDPH) for testing (Kurta, 1979). The bats were not obtained through any organized collecting effort, but resulted from accidental encounters between a bat and a concerned citi- zen. Most bats were turned in singly although occasionally more than one animal came from the same location. Only about five percent of the bats submitted are actually rabid. From 1968 through 1979, the MDPH has sent 909 of these bats totfluaMichigan State University Museum for species identification. Additional data, such as sex, location of capture and date of capture, were also recorded by Museum personnel for most of the specimens. Indicated dates of capture are actually the day on which the bat was received by the MDPH in Lansing and may exceed the actual capture date by one or two days (Michael Huntzinger, personal com- munication). Since 1971, most non-rabid animals have been retained in the collection of The Museum. 19 Museum Survgy I visited a number of colleges and universities in order to examine the Michigan bats in their mammal collec- tions. Collections inspected were located at the Michigan State University Museum (MSU), the University of Michigan Museum of Zoology (UMMZ), Michigan Technological University (MTU), the Andrews University Museum of Natural History (AU) and Wayne State University (WSU). Other insti- tutions supplied lists of specimens in their care. These included Olivet College, Adrian College, Northwestern Michigan College, Western Michigan University, Central Michigan University and the University of Michigan Biological Station at Douglas Lake. Since inexperienced observers may misidentify the various species of Myotis, and even confuse Myotis and Eptesicus, I used data con- cerning these genera only if I could verify the identifi- cation. Specimens submitted to the MDPH for rabies testing and currently housed at MSU are not considered part of the museum survey, but are discussed separately. Geographical Distribution Since W. H. Burt published The Mammals of Michigan in 1946, there has been no attempt to update the county distribution of Chiroptera in the state. I have surveyed the available literature and gathered information from museum collections, rabies submissions and my own field work in order to provide a more accurate picture of the 20 geographic distribution of bats within the entire state. For intrastate comparisons, I frequently use the 44th parallel (Figure l) as a convenient dividing line. Counties at or N of that line represent 50.6 percent of the state's land area; counties S of the 44th parallel make up 49.4 percent (see Emmons, 1977). Although a small portion of Huron County is N of the 44th parallel, this county was included in the southern group. Besides dividing Michigan into two approximately equal-sized sections, the 44th parallel also roughly indicates the location of a major soil change within the state (Millar gt gt., 1965). Approximate continental distributions indicated for each species on their individual range maps are based on Barbour and Davis (1969), Hall and Kelson (1959), Watkins (1972), Fitch and Shump (1979), van Zyll de Jong (1949) and Findley and Jones (1964). A Statistical Procedures Stated mean values are always followed by t 1 standard error of the mean. All Chi square tests performed with a single degree of freedom utilized Yates' correction for continuity (Zar, 1974). RELATIVE ABUNDANCE Results Seventy-eight reported bat roosts were visited within the study area. No bats were detected at eleven sites. Sixty-six roosts were utilized by E. fuscus and only one was occupied by E. lucifugus. Out of 657 bats from south- ern Lower Michigan that were received by the MDPH, 95.3 percent were big brown bats; red bats were the second most common at 2.6 percent (Table 2). Total mist-netting captures show E. fuscus making up 59.5 percent of the catch (Table 3). M, lucifugus accounted for 18.3 percent and E. borealis for 13.3 percent of all bats netted. Ninety-one percent of the little brown bats, however, were caught along the Thornapple River (N18- 24). If Thornapple River sites are excluded, the per- centages become 68.6, 20.0 and 4.0 for big brown bats, red bats and little brown bats respectively. Eptesicus fuscus and E. borealis were the species most frequently netted based on the number of sites at which each was captured (Table 4). 21 22 Table 2. Bats submitted for rabies testing to the MDPH from the southern four tiers of counties in Lower Michigan. Number Percent of Submitted Total Eptesicus fuscus 626 95.3 Lasiurus borealis 17 2.6 Lasiurus cinereus 6 0.9 Lasionycteris noctivagans 2 0.3 Myotis lucifugus 3 0.5 Myotis keenii 2 0.3 Myotis sodalis 0 0.0 Pipistrellus subflavus 0 0.0 Nycticeius humeralis l 0.2 TOTALS 657 100.1 23 Nae a.aa o.ooa mun o OOH Rom mqaeoa 0.0 o o.o o 0.0 o mHHmumEBS mswoofluomz 0.0 o 0.0 o 0.0 o ms>mam35m mDHHmuummem o.m 0H q.m o n.m 0H mwam©0m meth m.H m 0.0 o m.H m chmmx mwuoNS m.wH Hm o.¢ m n.n~ an mnwwmwonH mwuowm m.o a 0.0 o m.H a mamwm>wuooa mfiumuohaowmmq m.N HH o.q m m.H a mnmnocwo mauswmmq m.ma on o.o~ mm o.¢ «N mwamouon mahswmmu m.am mow o.mo ONH o.mm ASH woumsm msoammumm unmoumm wousuamu HmnEsz unmoumm wounummo Honesz unmonom umpfluamo Honadz Hm>wm mammmCH0£H Bamoxm mmuam Haa Hm>wm mamamnuonfi .mama use mesa scum muasmmu weauuma-umaz .m magma 24 Table 4. Number of non-Thornapple River sites at which each species was netted in 1978 and 1979. Thirty-two sites were sampled. Number of Sites Percent Eptesicus fuscus 25 78.1 Lasiurus borealis 14 42.4 Lasiurus cinereus 4 12.1 Lasionycteris noctivagans 0 0.0 Myotis lucifugus 3 9.1 Myotis keenii 0 0.0 Myotis sodalis 4 12.1 Pipistrellus subflavus 0 0.0 Nycticeius humeralis 0 0.0 25 Discussion Roost visitations revealed that the big brown bat was the chiropteran most commonly associated with buildings in southern Lower Michigan. The large proportion of E. fuscus obtained through rabies submissions is expected in light of the roost data. Obtaining bats through citizen captures favors E. fuscus because this chiropteran is frequently associated with man-made structures and because the big brown bat is a year-round resident, while all other species are apparently migratory (see Species Accounts). The mist-netting effort also yielded mostly E. fuscus (Table 3). Although E, lucifugus made up 27.7 percent of the catch along the Thornapple, it was only 4.0 percent of the total from the other 32 sites in the study area. A nursery colony of little brown bats was probably located near the Thornapple River localities (see Species Accounts), and its presence probably influenced my results. The four-percent figure from non-Thornapple locations is probably more indicative of this animal's true relative abundance in southern Lower Michigan. This conclusion is supported by the roost visitations and rabies submissions and by the very few summer-caught specimens found in museums. A possible reason for the relative scarcity of any Myotis or Pipistrellus in southern Lower Michigan may be the distance from suitable cave or cave-like hibernacula. Except for Bear Cave, this part of Michigan is devoid of 26 caves (Davies, 1955). The distance to the known hiber- nacula shown in Figure 4 averages about 340 km. All the Michigan Myotis and the pipistrelle are apparently obligate cave hibernators (Barbour and Davis, 1969). It is possible that the long migration needed for these animals to summer in southern Michigan may be a limiting factor in their distribution. That climate is probably not affecting the distribu- tion is shown by the fact that these species are relatively more common in northern Michigan (Stones and Fritz, 1969; Miller, 1955; see Species Accounts) and in Indiana (Mumford and Cope, 1964). For example, within 80 km S of the Michigan border, in Indiana, there are 42 known E. fuscus maternity colonies and 11 E, lucifugus breeding colonies (Mumford and Cope, 1964; this study). In the more northerly and larger area of this study, I managed to locate 55 big brown bat nursery roosts but only one small little brown bat nursery colony. Although Humphrey and Cope (1976) have recovered banded little brown bats up to 460 km away from their hibernacula, movements such as this appear to be extremely rare (Fenton, 1970; Brenner, 1968; Griffin, 1945; Fisher, 1955; Humphrey and Cope, 1976). Based on all indices used, the big brown bat and the red bat are the most abundant species in the study area. It is difficult to determine which species is actually the most numerous, because of their great differences in habit. Visits to building roosts and the rabies submissions Figure 4. 27 Cave or cave-like hibernacula close to the study area. Locations are from: 1. Long (1974); 2. Greeley and Beer (1949); 3, 4. Stones and Fritz (1969); 5. Kurta (1980b); 6, 7. Fenton (1972); 8. Brenner (1974); 9. Mills gt gt., (1975); 10, 11. Hall (1962); 12, 13. Humphrey and Cope (1976); 14. Whitaker (no date). 28 46" 4o- 160 no no 29 obviously yield results that are biased towards E. fuscus. A comparison of total numbers mist-netted is not adequate either, since a single night of netting near a big brown bat maternity roost could greatly influence the results. Perhaps the most reasonable conclusion at this time is simply that Eptesicus fuscus is the most common colonial chiropteran in southern Lower Michigan and that Lasiurus borealis is the most abundant solitary tree-dweller. There is the possibility that my results are biased because of different species-specific foraging habitat preferences. Some species may prefer to hunt over ponds or over land, rather than along streams. Mist-netting does not appear to be a very efficient or effective technique for determining if these possible differences do exist. The use of ultrasonic sound detectors and appropriate recording devices may hold more potential for this type of ecological research (see Fenton, 1970a, 1973). Possible bias introduced by sampling only stream habitats will be discussed in the appropriate species accounts. SPECIES ACCOUNTS Big Brown Bat Eptesicus fuscus (Palisot de Beauvois) Maternity Roosts Sixty-six reported bat roosts were used by the big brown bat within the study area. Fifty-four of these apparently sheltered summer nursery colonies, while five others were occupied by solitary males. The approximate location of each maternity roost is shown in Figure 5 and listed in Appendix B. Throughout the text, the letter R followed by a number will refer to particular maternity roosts as indicated in the figure and the appendix. The function of the remaining seven roosts was not determined. Houses contained 25 nursery colonies; barns sheltered 21. Four maternity colonies were located in commercial buildings, while three resided in churches; one was found in a hollow tree. Mumford and Cope (1964) state that the E. fuscus breeding colonies in Indiana are most frequently found in barns, followed by churches and then houses. Davis gt gt. (1968) found most colonies in churches in Kentucky. 30 31 Figure 5. Location of Eptesicus fuscus maternity roosts. Numbers refer to the more exact locations given in Appendix B. 32 un '1 «.1 ... ... - 020 m 2.2!: 0:“ OJCJ '4.‘ .1 JCIUi'01'UJUOI'- _ 20_ _ _ 30— «.0 . o _ _ ... .._ ... .....n.. .,--..-...-.--..-..-!.-...-.....-- 2.3.5 o_ . _ o_ _. :0 So _ 20 . 2 . . .0 _ _w _ _ _ . -I--|. ...-|.......-.I.-in.li_.-t l .5 . _ .. .._.. "1. . _- .. . n «n . 0 av . _ on . o . -hlksl l_. l -L 52.3.: .8..- Tu. rnv 1 v. u o. 33 Barbour and Davis (1969) and Mills gt gt. (1975) both mention that the big brown bat frequently roosts in attics. In 88 percent of the Michigan house roosts, the majority of the bats were resting within the walls or in an overhanging eave. Only three house attics (R9, 11, 14) contained more than three bats. One of these attics (R14) contained about 50 bats on 18 July 1978, but all animals located on 24 April 1979 were within the wall. The other two attics were not revisited. That bats could enter most of the attics was shown by the presence of some droppings and the occasional live or dead animal that was found. Apparently E. fuscus in Michigan preferstjuaclosed-in areas of eaves or walls to the comparative spaciousness of the attic. Roosting sites within barns varied. Some bats hung on roof supports near the ceiling; many hung from the peak, often at the ends of the building. Occasional females roosted within support beams or between vertical beams and the wall. Two colonies were found between wall boards and outer siding. Although roosting sites varied between barns, they were relatively constant within an individual structure. Bats were often located high overhead in dark barns by searching for the droppings that accumulate under- neath preferred roosting sites. Only two barn roosts were shared with domestic live- stock. One Ingham County barn (R10) did house two horses and a mule. Another barn roost (R6), in Cass County, also contained about 30 pigs. Although big brown bats may 34 prefer the relative quiet of an unoccupied barn, this association may be fortuitous. Barns that do not harbor livestock may be more open, through design or neglect, thus providing easier access for the bats. Tree Roost of a Maternity Colony In addition to locating breeding colonies in build- ings, one nursery colony (R49) was discovered in a hollow beech tree (Fagus grandifolia). This tree was situated near the shore of Indian Lake, Cass County. The beech tree was an estimated 21 m in height and was about 0.68 m in diameter. A narrow crack, 5.0 cm wide, began 5.2 m above the ground and extended upward another 1.1 m along the eastern side of the trunk. According to the landowner, the bats had been using this crack to gain access to the hollow bole for at least twenty years. Forty-one individuals left the tree on the evening of 20 July 1979. Known tree roosts of E. fuscus maternity colonies appear to be rare. Cahalane (1932) first reported such a colony in 1932, discovering it after an elm tree containing the colony had been cut down. Christian (1956) described a small breeding colony in Maryland that alternated between the shutters of a house and a nearby oak tree. The only other reported group of E. fuscus that utilized a tree was a number of animals that had been displaced from their usual roost during a homing experiment. After their 35 release, some of the bats took up residence in a nearby hollow tree (Davis, 1969; Mills gt gt., 1975). Age of Building Roosts Landowners supplied approximate ages for thirteen of the houses used by E. fuscus breeding colonies. The aver- age age was 80.1 yr and ranged from 35 to 175 yr. The average age of five barns was 87.0; all were at least 75 years old. The mean age for all eighteen of these roosts was 82.0 yr. This seeming preference for older structures has pre- viously been noted by Schowalter and Gunson (1979) in Alberta. They attribute this preference to a strong site attachment by female big brown bats. Although such an attachment has been demonstrated by a number of banding studies (Beer, 1955; Davis gt gt., 1968; Brenner, 1968), an additional reason may be the physical condition of the building itself. Older structures are more likely to be in various stages of disrepair and may simply provide easier access to acceptable roost sites. Species Associates at Nursery Roosts In the western United States, E. fuscus occasionally shares its roost with Tadarida brasiliensis, Antrozous pallidus or Myotis yumanensis (Barbour and Davis, 1969). Schowalter and Gunson (1979) and Mills gt gt. (1975) have reported nursery colonies of E, lucifugus and E. fuscus in the same building. Humphrey (1975) states that big and 36 little brown bat maternity colonies are found in the same building only about one-fourth as often as would be expected by chance alone, and he suggests that either active or passive exclusion is taking place. I found no evidence that E. fuscus was sharing its roost site with any other chiropteran in southern Lower Michigan. Location of Exits at Maternity Colonies There was no apparent pattern to sites used as exits by big brown bats living in barns. Bats left through open doors, broken windows, cracked boards or anywhere along the roofline. Out of 23 house roosts where I was able to determine the exit point, fifteen were located at the point where a chimney runs up the side of a building and inter- sects the roofline. House colonies that utilized other exits were generally located in structures without side chimneys. One of the church colonies (R44) also left from behind the chimney. At two barn roosts (R20, 47), the owners stated that some bats were occasionally seen flying from behind the chimney of the nearby house. Apparently as a building ages, the chimney will pull away a few centi- meters from the side of the structure, enabling the bats to enter. All exits at houses were at least 3.5 m above the ground. Although many homeowners claimed to have found bats in their basement and insisted that the animals must have entered through small cracks near ground level, I 37 could find no evidence for this. A likely explanation for basement sightings is that the bats had crawled through the walls from some higher point of entry. Having an entrance and exit well above the ground could possibly discourage potential predators and also allow the animals more space in which to drop before gaining sufficient air speed to initiate flight. Time of Evening Flight Four evening flight observations were made at Hardy Church in May 1979 without any disturbance in the attic. Average emergence time of the first bat was 25.8 t 2.4 minutes after sunset. An extremely heavy south wind esti- mated at 24 to 32 km/hr did not prevent the bats from leaving on 7 May. The wind was strong enough that no bat could fly into it, although about twenty attempted to do so and were driven north. A fifth observation on 25 May took place on a cold (8.8 C at sunset), overcast evening with intermittent rain. No bats had emerged by the end of the 60-minute observation period. In addition to observations at Hardy Church, the emer- gence time for the first bat was also recorded at fourteen different E. fuscus nursery roosts on twelve separate nights. The mean emergence time was 17.9 i 2.4 minutes after sundown. The median was 20.5 minutes. The earliest time of departure was exactly at sunset on 3 July 1979 from an Ingham County house roost (R40). The latest first 38 departure was 28 minutes after sundown on 25 July 1978 from a St. Joseph County barn (R20). There is apparently considerable variation in the emergence times of colonial Nearctic vespertilionids. Vaughan (1959) reported that Pipistrellus hesperus leaves at about 30 minutes before sunset. He also states that Myotis velifer departs between 17 and 64 minutes after sun- down and that Macrotus californicus will not begin to for- age until 60 to 120 minutes after sunset. In Indiana, little brown bats will begin leaving the roost between one and 22 minutes past sundown (Humphrey and Cope, 1976). Different species-specific emergence times have been sug- gested as a means for avoiding interspecific competition (Erkert, 1978), but I know of no study that has investi- gated this possibility. My data gives only a rough approximation as to the emergence times of E. fuscus. Unfortunately, I did not determine any possible effects of cloud cover or moonlight. Although O'Farrell and Studier (1975) state that light intensity has no effect on emergence times of M, lucifugus and M. thysanodes, studies with other species have revealed the opposite effect (Gould, 1961). My observations of 7 and 25 May at Hardy Church suggest that E. fuscus does not alter its daily emergence because of high wind alone, but that it may not forage during cold and wet weather. The effect of inclement weather on bat activity is frequently mentioned in the literature (O'Farrell and Studier, 1975; 39 Greenhall and Paradiso, 1968; Fenton, 1968, 1969; Jones, 1965; O'Farrell and Bradley, 1970). Nursety Roost Population Size Flight counts were made at 21 E. fuscus maternity roosts, excluding Hardy Church. Average population size was 51.6 individuals and ranged from 5 to 150 bats. The Michigan colonies appear to be slightly smaller than those reported by Mumford and Cope (1964) from Indiana. Their mean colony size was 65 animals and varied from 15 to 260 bats. Davis gt gt. (1968) mentioned colonies ranging from 14 to 124 bats in Kentucky, and Mills gt gl. (1975) found from 8 to 700 big brown bats at nursery roosts in Ohio. Although these figures do give an indication of average colony size, there is considerable variation during a single season at any one colony (see Population Size at Hardy Church). Prggnancy, Parturition and Lactation On 28 May 1979, I visited Hardy Church, but did not see any neonates nor did I hear any of the characteristic "chirps" (probably the audible portion of the "i" call as described by Gould, 1975) emitted by apparently distressed newborn. On 5 June, at 2040 hours, I again entered the attic. Two of the 19 females captured were lactating. Two juvenile females, hairless, with eyes closed, pinnae not erect and still possessing the shrivelled remains of the umbilical cord, were also taken. The two neonates had 40 forearm lengths of 18.0 and 19.0 mm. Using the formula supplied by Burnett and Kunz (Table l), the estimated age of the young bats was 1.8 and 2.5 days respectively. This indicates that parturition may have occurred as early as 3 June. This is the earliest birth date recorded in my study. The last pregnant female obtained through mist-netting was captured over the Thornapple River (N20) on 18 June 1979. The last pregnant female captured at a nursery roost was found on 24 June 1978 in a barn (R7) near Marcellus, Cass County. On 8 July 1978, while crawling through an attic roost (Rll) near Pontiac, Oakland County, I obtained an immature male with a forearm length of only 23 mm. The Burnett-Kunz equation indicates a birth date of 3 July. This is the latest parturition date recorded during this project for southern Lower Michigan. The first lactating female was obtained on 5 June at Hardy Church. The latest individual that was definitely lactating was mist-netted over the White Pigeon River (N7), St. Joseph County, on 6 August 1979. Another female did yield a small, yellowish-colored drop of milk on 12 August 1979, but the amount of hair regrowth in the mammary region indicated that she had not been suckled for some time. Lactating big brown bats, therefore, can be found through- out June and July and into early August in southern Lower Michigan. The early August cessation of lactation, coupled with a 3 July date for latest birth, agrees reasonably well 41 with published mean lactation periods for the big brown bat of 32 and 40 days (Kunz, 1971, 1974). In Kentucky (Barbour and Davis, 1969) and in southern California (Krutzsch, 1946), most young are born in late May and early June. Parturition occurs mainly during early June in Indiana (Whitaker and Mumford, 1971), but through- out most of June in Iowa (Kunz, 1971). Schowalter and Gunson (1979) believe that most E. fuscus give birth between 5 June and 12 July in Alberta. Barbour and Davis (1969) have pointed out that there is apparently a north- south trend with parturition occurring later in more northern regions. The data from Michigan conform to this general pattern. Reproduction at Hardy Church The pattern of reproductive events for E. fuscus living at Hardy Church is indicated by the changes in aver- age adult female weight (Figure 6). Mean weight was maximal during the visit of 5 June. On that day, 19 females were examined; 17 were still pregnant and two were already lactating. The average weight fell from 21.5 g on 5 June to only 16.3 g on 19 June. Out of 21 bats captured on 19 June, none were still pregnant. This suggests that parturition at the church occurred within a 16-day period, or less, between 3 and 19 June. Weights continued to drop slightly until 20 July. The observed postparturition decline is probably related to changes in body fat levels. 42 Figure 6. Weight change of adult female E. fuscus at Hardy Church. Solid circles are mean values. Error bars encompass t 1 standard error. Numbers indicate the sample size. 43 pansy—hum hm: 03¢ >42. *5 .. >34 mu m w s on up a au 9 a mu 9 a on on o p F - b b h p - p . n b b b h b 1 l2. T- QP n I o 10.. up n 1 or . .. law 3 a a o I r '8 a = I run or .F a a r N Iva (5) mam AOOB 44 Weber and Findley (1970) report that females have "a higher fat content in June when most are pregnant, followed by a slight decrease in July when most are lactating." The increase shown after 16 July coincided with the cessation of lactation in some females. Only five of 14 adult females were still lactating on 30 July; no lactating females were found on 10 August or subsequent dates. The large increase shown on 4 September is based on only two bats, but it may be indicative of the actual trend, showing the increased body weight as the animals put on fat for hibernation. Beer and Richards (1956) do report that Minnesota E. fuscus females enter hibernation at about 21.5 g. The seasonal weight change of one female (#017) is shown in Figure 7. This bat was captured on six different dates, more than any other individual. The pattern of weight change at the Hardy colony as a whole and in bat #017 is essentially the same as that seen at an E. fuscus maternity roost in Kansas (Kunz, 1974). Population Size at Hardy Church The number of individuals occupying Hardy Church was recorded every seven to ten days from 7 May to 10 September 1979 (Figure 8). The population had an early peak of 47 bats on 21 May, but fell to 39 individuals by 24 June. The largest flight occurred on 10 July, but population size dwindled to only 18 animals on 10 August. This pattern 45 Figure 7. Weight change in a single E. fuscus female (#017) at Hardy Church. 46 Egg—hum Baas: >43... “2...... >(! 5N hr 5 ON 0.. 0 an Dr G Or .00 ON 0.. p b p _ . p u p p p P P h roux w4<2mu 13. 12. top law r3 (6) mmam mos 47 Figure 8. Change in population size at Hardy Church. 48 cmmfiwhaum .539: 5:... mzaa >5. pm 2 n ma 9 o as 9 a an 2. a on ON a. P p . n p p P . . p p p p p P I on I on a. I 9 .. on r 8 $118 $0 HBBWDN 49 (Figure 8) is very similar to that seen by Humphrey and Cope (1976) at two little brown bat colonies in Indiana. The early decline from 7 to 21 May may be explained by two factors. First of all, E. fuscus is often very sensitive to disturbance. Barbour and Davis (1969) note that some roosts may be completely abandoned after a visit from a biologist. The second possible cause for the observed decline is the departure of transient animals. The movement of migratory animals has been suggested by Humphrey and Cope (1976) to explain a similar pre- parturition decline at M. lucifugus colonies. The seasonal peak that occurred on 10 July is most likely related to early flights of young bats born the pre— vious month. Parturition at Hardy Church apparently took place during the first two weeks of June. Kunz (1974) reports that immature big brown bats are able to fly between thee and four weeks of age. The precipitous decline in population numbers from mid-June into August may have been caused by disturbance effects and/or the natural movement of young and post- lactating females out of the roost (Humphrey and Cope, 1976; Brenner, 1968; Barbour and Davis, 1969). That con- siderable natural movement of big brown bats may occur at this time is suggested by the number of bats submitted for rabies testing (Figure 9). The vast majority of the bats, 42.4 percent, are turned in during the month of August, which may indicate that the bats are spending less time 50 Figure 9. Number of big brown bats submitted for rabies testing from the southern four tiers of Michigan counties by month. 51 N=620 50' 40- l 1 . s a SHDLdVO 'IVLOJ. :IO 11033836 10" MONTH 52 within the security of their home roosts. Barbour and Davis (1969) state that colonies in New England may begin to break up when the young are weaned. Most young at Hardy Church were probably weaned by late July, if Kunz's esti- mated mean lactation period of 32 to 40 days is correct (Kunz, 1971, 1974). Litter Size and Pregnancy Rates A breeding colony of E. fuscus living behind a house shutter in Lansing, Ingham County, was exterminated by Robert Goodsell on 24 May 1976. The bats were donated to the Michigan State University Museum and are preserved as fluid specimens (#25027-25058) or as skins and skulls (#25059-25069). Examination of the alcoholics and the tags accompanying the skins revealed that all 42 adult females were pregnant on 24 May. Forty—one animals possessed two fetuses and one bat yielded only a single embryo in the right uterine horn. All four females (MSU 4329-4332) obtained near Weston, Lenawee County, on 30 May 1959, by D. Hubbard were preg- nant. Three bats were bearing twins and the fourth carried a single fetus. Six out of eight females captured on 22 May 1979 at an Eaton County house roost (R31) were in the early stages of pregnancy. Five individuals carried two small embryos; the sixth held only one. At Hardy Church, 52 out of 56 adult females examined in June and July were either pregnant, lactating or post-lactating. 53 Litter size in the related European species, E. serotinus, is only one (Kleiman, 1969). Eptesicus furinalis, a Neotropical, polyestrous species, produces two young in the first litter and invariably only one in the second (Myers, 1977). Populations of E. fuscus in western North America apparently only produce one young per year (Schowalter and Gunson, 1979). The results for Michigan, t.g., generally two young per litter, agree with other studies on eastern populations of the big brown bat (Christian, 1956; Kunz, 1974; Whitaker and Mumford, 1971; Davis gt gt., 1968). Such high rates of pregnancy, as seen in the Goodsell colony and at Hardy Church, are common among colonial Nearctic vespertilionids (Barbour and Davis, 1969; O'Farrell and Studier, 1975' Tuttle, 1975; Humphrey and Cope, 1976). Sex Ratios At Hardy Church, I punch-marked 24 male and 25 female juveniles in 1979. During both years of this project, I examined 206 immature animals at all breeding colonies; 117 were male and 89 were female. This ratio is not signifi- cantly different from 50:50 (Chi square - 3.54; d.f. = l; p > 0.05). Combined mist-netting data, for all juvenile catches prior to 16 August each year, showed a capture ratio of 26 males: 20 females and was not different from '50:50 (Chi square = 0.54; d.f. = l; p > 0.05). It would appear that the number of males and females at birth is 54 approximately equal. These results agree with the findings of Kunz (1974), based on embryo counts in Kansas, and with the report by Brenner (1968), based on juvenile banding records at Ohio and Pennsylvania maternity colonies. Although males and females are equally represented in juvenile counts, this is not true for the adults. From Goodsell's colony, 42 out of 43 adults were female. At Hardy Church, 86.8 percent of the 68 adults punch-marked were female. Using all full-grown animals taken from all nursery colonies, the sex ratio is 24:187, or 88.6 percent female. Such high percentages of adult females at summer roosts is, of course, common in E. fuscus (Schowalter and Gunson, 1979; Davis gt gt., 1968) and in many vespertilionids (Bradbury, 1977; Barbour and Davis, 1969). Seasonal Activity Although southern Lower Michigan is almost totally devoid of caves (Davies, 1955) or cave-like hibernacula, indications are that most big brown bats spend the winter in this area. Banding studies have consistently shown that big brown bats rarely move more than 80 km from their original banding site (Goehring, 1972; Beer, 1955; Barbour and Davis, 1969; Mills gt gl., 1975). That many E. fuscus do remain in Michigan is shown by the number of bats turned in for rabies testing during the winter months (Figure 8). In the southern four rows of counties, 11.0 percent of all big brown bats submitted are from December through February. '55 Numerous museum specimens also indicate the year-round presence of E. fuscus in the study area. Where do these bats hibernate when the cold weather effectively eliminates their food supply? Although many summer-roost owners claim to hear bats crawling or squeak- ing inside building walls during winter, none reported visible groups of bats in their barns or attics. The only torpid individuals that I discovered were two E. fuscus found inside a rolled-up carpet stored in an East Lansing, Ingham County, attic on 10 January 1979. Numerous authors mention the occasional big brown bat found torpid in attics and the frequent sightings of active individuals in build- ings during the winter months (Mumford and Cope, 1964; Whitaker and Mumford, 1971; Goehring, 1972; Schowalter and Gunson, 1979; Whelden, 1941; Toner, 1935; Nero, 1959). Mills gt gt. (1975) even report a colony of 25 hibernating E. fuscus in a school attic in Logan County, Ohio. Based on rabies submissions, the lack of Michigan caves and the absence of long-distance migration in the species, it seems likely that big brown bats do remain in southern Michigan throughout the year and that many probably hibernate in buildings, possibly within the walls where they would not be easily detected. When these bats leave hibernation may be inferred from reproductive data and from studies in other states. Barbour and Davis (1969) estimate that the gestation period of E. fuscus is about 60 days. Ovulation, therefore, may 56 occur in southern Lower Michigan as early as 4 April, assuming 3 June as the earliest parturition data and 60 days as the gestation period. Since many Nearctic vespertilionids will ovulate within a few days of leaving hibernation (Guthrie, 1966; Pearson gt gt., 1952), hiber- nation for E. fuscus may end as early as the beginning of April. Field observations reveal that many E. fuscus are active by mid-April. On 19 April 1979, a few big brown bats were seen foraging over the Thornapple River (N20). On 20 April 1979, I counted 30 E. fuscus leaving a house (R9) in Onondaga, Ingham County, and heading out over the Grand River, presumably to feed. No bats were present at Hardy Church on 16 April 1979, but 48 emerged on the even- ing of 23 April. I did not determine the exact dates of nursery colony breakup. Many E. fuscus may use the same building as both a summer roost and a winter hibernacula (Schowalter and Gunson, 1979) and so, in a sense, there would be no colony breakup. Brenner (1968) reports that big brown bats left a barn roost in north-central Ohio in early November, while those residing in a stadium in east-central Pennsylvania left in late October. He infers that the bats had returned to their winter quarters and suggests that the onset of colder weather may have been the stimulus which influenced their departure. His data indicates that E. fuscus usually left when the minimum daily air temperature fell to between 57 3 and 5°C. Such temperatures are common in southern Lower Michigan during October and November (National Oceanic and Atmospheric Administration, 1979). Observations made on the Red Cedar River (N33) and along the Thornapple River (N20) in late October and early November, at sunset temperatures of 11 to 15°C, showed very little bat activity even though both sites had yielded large numbers of bats earlier in the season. Based on this indirect evidence, it seems that big brown bats in southern Lower Michigan were active from early April until possibly late October. Geggraphic Distribution Eptesicus fuscus is now known from 57 Michigan counties (Figure 10), from South Manitou Island (Scharf, 1973), and from Isle Royale (Burt, 1946). It is relatively less common in the more northern sections of the state. Only 28.6 percent of all bats submitted for rabies testing from N of the 44th parallel were big brown bats, while 94.6 percent from south of the line were this species (Table 5). Although some big brown bats hibernate in the mines of the Upper Peninsula, they are greatly out-numbered by Myotis (Stones and Fritz, 1969). The reason for the northern decrease in relative abundance is not known. 58 Figure 10. Counties from which Eptesicus fuscus has been reported. Open circles are counties mentioned in Burt (1946). Solid circles represent new records. 59 .fi , Q___ _. ar- 7“ I .. .—-_-~r—EES£ rum: ‘ "r nus o 5!: an I " ” " I 5 1: C i D g _‘—+-— |I1C~r".s ’ _J— - -__L._. _ m. f etc-om LAKE M'CHIOAN 60 m.mm mmm H.0OH mm mAmamnnm msHHmuumwmam 0.0 o 0.0 o mwampom mwuozz «.0 m m.mH ma Hwaomx manomz m.o m o.m¢ we m5w3mwosa mwuohz m.o q H.m m mcmwm>fiuooc mwumuuwdowqu m.H OH o.H H mnmumcwo mounwmmd m.N NH H.m m mHHmmHon mandamwa o.¢m men o.mN mm mdomsm maowmmumm unwoumm pmuuwfifidm unmouom wouuHEQSm nonesz Hmnafiz nusom nunoz .Hmaamuma suqq mzu mo m paw z Eoum cmwwzoflz SH waflumou mownmu How wmuufiapsm mumm .m maamh 61 Little Brown Bat Myotis lucifugus (Le Conte) Reproduction Only one small nursery colony of the little brown bat was actually located within the study area. These bats lived inside a large, 90-year old, barn-like structure, near Dowagiac, Cass County. Although flight counts were not made, daytime estimates of the population, including non-volant young, were eleven bats on 23 June 1978 and thirteen individuals on 16 June 1979. In 1978, forearm lengths of two captured juveniles were 13 and 19 mm. Using the Burnett-Kunz equation (Table l), estimated parturition dates were 20 and 23 June. None of the three adult females examined appeared to be preg- nant. In 1979, the forearm size of four juveniles indi- cated birth dates of 12 to 15 June. Out of the six adults caught on that day, one was lactating and five were still pregnant. Little brown bats at this colony are apparently born in mid-June. Another maternity colony of little brown bats was located only 16 km S of the state boundary, near La Porte, La Porte County, Indiana. Data from this Indiana roost are included because of its proximity to the study area and because the climate, tOpography and vegetation are similar to those in nearby southwestern Michigan. This particular breeding colony resided in a lSO-year old farmhouse. Two 62 hundred and six of a daytime-estimated 300 individuals were captured on 23 July 1978. Adult sex ratio was 5:107; juvenile sex ratio was 44:45. The ratio of young bats to adult females was 0.93. These ratios are consistent with those obtained in other studies, as summarized by Humphrey and Cope (1976). All young were volant. None of the adults were pregnant and only 37 were still lactating. The colony was revisited on 16 June 1979. Fifty-two animals were caught and examined on that day. Juvenile sex ratio was 7:7; all 38 adults were female. Eighteen of the adults were pregnant and 18 were lactating, while two appeared to be non-reproductive. The median parturition date for this colony in 1979, therefore, may have been 16 June. Available forearm lengths indicated that the oldest juvenile was at least eleven days old; twelve neonates were less than six days old. Parturition at this maternity roost apparently occurred throughout most of June in 1979. Although no other actual colony sites were located, another probably did exist near Vermontville, Eaton County. The large number of little brown bats netted along the Thornapple River (Table 3) and the fact that about 73 per- cent were adult females or young of the year strongly sug- gest the presence of a nearby nursery roost. The first lactating female was snared on 18 June 1979. The last pregnant individual was caught on 24 June 1979, and the last lactating female was caught on 12 July of that year. Volant juveniles were not netted until 1 August 1979. 63 Although E. fuscus is the most abundant colonial chiropteran in southern Lower Michigan, some breeding colonies of M. lucifugus do exist. The data from the two roosts examined and from the Thornapple River indicate that this species gives birth throughout most of June in the study area. Lactating females may be found from early June until late July. These dates may be slightly earlier than in the Upper Peninsula where parturition occurs between 5 June and 8 July (Stones and Fritz, 1969). Birth rates in other regions are summarized in Humphrey and Cope (1976). Bear Cave Out of 356 different bats captured at Bear Cave in 1978 and 1979, 75.0 percent were M, lucifugus. Myotis keenii made up 24.4 percent of the total, while less than one percent, only two individuals, were E. borealis. Males made up 73.5 percent of all eastern long-eared bats caught and 66.3 percent of the little brown bats; both red bats were males. Only 15 of 216 little brown bats and three of 54 long-eared bats that were punch-marked in 1979 were ever recaptured on the same or succeeding nights. The number of Myotis lucifugus captured per hour is shown in Figure 11. Activity peaked within the third hour after sunset and again during the sixth hour. This is distinctly different from the temporal foraging pattern of the little brown bat which is unimodal (Kunz, 1973). 64 Figure 11. Nightly activity of M otis at Bear Cave in September of 1978 and 1979 Data points represent the percentage of the total species capture obtained within each hour after sun- down. N = 282 for M, lucifugus. N = 90 for M. keenii. 65 32:5 .3:- :3: :53. 3.0»! u 25:20:. 2.0»! o h 1.. In jaw 10.. 101. rva ”ma-3 "goods "to; so wound 66 This prolonged pattern of nightly activity, along with the predominance of males, the low recapture rate and the abundance of Myotis in an area of Michigan where it is a rare summer resident (Tables 2 and 3) indicate that Bear Cave is a "swarming" site. Swarming, according to Fenton (1969), "refers to the flight of bats through hibernacula in the late summer and early fall." This activity brings males and females together for copulation and possibly introduces the young to potential hibernation sites (Fenton, 1969). As at other swarming sites (Hall and Brenner, 1968; Fenton, 1969), mOSt bats caught at Bear Cave were probably migrants, possibly moving from summer roosts in Michigan to cave hibernacula in southern Indiana or perhaps Kentucky. In addition to monitoring swarming behavior, I also made daytime visits to Bear Cave in order to look for roosting bats on 6 June, 12 July and 7 September 1978 and 5 September 1979. Only on 7 September 1978 did I detect any bats; two Myotis were flying in the cave and another bat could be heard inside a small crevice. The owners of the cave, however, stated that from one to three bats fre— quently disrupted cave tours throughout the summer. Bear Cave is apparently used as a day roost for a few bats, probably adult males, in early summer and possibly by transients of both sexes in late summer and early autumn (see Humphrey and Cope, 1976; Hall and Brenner, 1968; Fenton, 1969). 67 Seasonal Activity Wood (1922a) states that "almost every winter individuals have been found in the building of the Museum of Zoology, at Ann Arbor." There are, however, no speci- mens in any of the museum collections that I examined that would support his claim, and I assume that most, if not all, little brown bats migrate out of the study area each fall in search of suitable cavern-like hibernacula. The evidence as to where M. lucifugus migrates to for the winter season is scant and equivocal. Some little brown bats may hibernate in Bear Cave. Unfortunately the cave is closed to human visitors during the winter, and I could not gain access to check on this possibility. There is, how- ever, a little brown bat in the collection of the nearby Andrews University Museum of Natural History (AU 146) that was taken at Bear Cave on 10 December 1965. Perhaps this bat had been hibernating at the cave when captured. Some M. lucifugus from.Michigan may migrate to the karst area of southern Indiana for the winter. A male, banded while hibernating at Grotto Cave, Monroe County, Indiana, on 8 February 1964, was later recovered near Bronson, Branch County, Michigan, in September 1964 (Figure 10; J. B. Cope, personal communication). Another little brown bat, also a male, banded on the same day at Grotto Cave was eventually found in August 1964, near Rolling Prairie, La Porte County, Indiana. The recovery site is only about 10 km S of Berrien County, Michigan. These are Figure 12. 68 Banding recoveries of Myotis lucifugus within 25 km of southern Lower Michigan from Fisher (1955) and J. B. Cope (personal communication). Grotto Cave, Monroe County, Indiana; . Rolling Prairie, La Porte County, Indiana; Bronson, Branch County, Michigan; . Douglas Lake, Cheboygan County, Michigan; . Windsor, Canada. MbUJNH 69 70 the only records of little brown bats being banded while at southern hibernacula and later being recovered within 25 km of Michigan. Other bats may migrate north to the caves and mines of the Upper Peninsula, rather than south to Indiana. Fisher (1955) banded an active little brown bat on 9 May 1951 at the University of Michigan Biological Station in Cheboygan County, Michigan. Twenty-three days later this animal was recaptured at Windsor, Ontario (Figure 12). Since most of the animals banded by Fisher were transients, this return may represent a true migratory pattern. On the other hand, such a long movement may have been just an extreme response to the unpleasant banding experience. Other than October and December records of M, lucifigus at Bear Cave, the latest that a little brown bat has been found in southern Lower Michigan is one mist- netted over the Thornapple River (N20) on 28 September 1978. The earliest spring record is a male (MSU 5477) captured by J. W. Winship on 12 April 1957, in Ingham County. Myotis lucifugus is a year-round resident in northern Michigan (Stones and Fritz, 1969). Geogrgphic Distribution Myotis lucifugus is now known from 48 counties in Michigan (Figure 13). It is also known from Isle Royale (Burt, 1946; Peterson, 1977), Mackinac Island (MSU 8076- 8085), Charity Island (Burt, 1946), Trout Island (Hatt gt 71 Figure 13. Counties from which Myotis lucifugus has been reported. Open circles are counties mentioned in Burt (1946). Solid circles represent new records. 72 ain't—$51.17 7 d d _ w r _ nu W. _..- ..... 3., ..... “w a . _r .1 ea c .. _. -..!-. c .1 1 . _. _ 4 ._ 1. 1. T a _ _ .u _v -wm & O ...H.JI-I-_.. ., -,_- -1 _ - ._. _. . I. _.. 1 _ m. . m 1. m . .m 0 _ a -7 ‘ u - W U 1 . o. . 73 gt., 1946), South Manitou Island (Scharf, 1973), North Manitou Island (Scharf and Jorae, 1980), Beaver Island (Ozoga and Phillips, 1964) and from Garden Island (Phillips 2E.él-: 1965). The little brown bat makes up 49.0 percent of all bats submitted for rabies testing from N of the 44th parallel, but only 0.7 percent from the south (Table 5). The abundance of M. lucifugus in the north may in some way be associated with the previously mentioned soil change, or it may be the result of having potential hibernacula rela- tively nearby (Figure 4). Indiana Bat Myotis sodalis Miller and Allen Pre-l978 Records Prior to 1978, the Indiana bat had been found in Michigan on only nine occasions. The first record is an unsexed, undated specimen that is currently housed in the United States National Museum (#5505). This animal was captured on Grosse Isle, in the Detroit River, Wayne County (Burt, 1946). Two other Myotis sodalis from Michigan are part of the collection at the University of Michigan Museum of Zoology. A female Indiana bat (UMMZ 91086) was caught by F. H. Test on 27 September 1946 in Ann Arbor, Washtenaw County. Almost a year later, on 10 September 1947, R. J. Porter obtained another female (UMMZ 92242) at Sylvan Pond, 10 km WNW Chelsea, Washtenaw County. The only other known 74 museum specimen is also a female, taken in Lansing, Ingham County, on 11 October 1974, and is now preserved in the Michigan State University Museum (#23985). Other pre-l978 records are five Indiana bats that were originally banded in Kentucky by W. H. Davis (personal communication) and later recovered in Michigan (Table 6). The location of all Indiana bat captures in Michigan are indicated in Figure 14. Mist-NettingECaptures Only three Indiana bats were mist-netted in 1978. The first M. sodalis was captured on 25 July as it flew over Mill Creek (N6) in St. Joseph County. This individual, a lactating female, provided the first evidence that the species was actually breeding within the state. The next capture was a juvenile female netted over the Shiawassee River (N37) on 15 August. The only other Indiana bat caught in 1978 was an adult female taken in Hillsdale County (N13) on 25 August. A total of 13 Indiana bats were mist-netted in 1979. On 28 June, a lactating female was captured about 100 m N of the Shiawassee River site of the previous year. Two other adult females were taken at a new St. Joseph County location on Big Swan Creek (N10). One bat was caught on 9 August and the other, still lactating, was snared six nights later. 75 Figure 14. Capture localities of Myotis sodalis in Michigan. Open circles are records mentioned in Burt (1946). Closed circles represent new capture localities. Ar -.‘ 76 c' uouu. MARIO D'- “A.“ 634.! HHS nxapmw l 1 5'0 0 ”.mun- W twmm— thin-‘07 ~+ I *f‘sm‘taaan- l - «was I 0 a—o—.—. w! ..nu. ant-ni- s. I‘L. ' 3 O l II A l l .1 u.»- ,_. . _..-.--.--lg n ' 1 _,_ l i I L-_.-._L . .ql: _ a n .m _m .. . _ m 3.. .. 1. 1 .. a . _. 4 law a 4--- 1-11.. _ ”a--. ...... _. _ rip-@ .. _. _ _ . O_ u. m .w . Li}. .1... _... c. .1 _ .7 . . I J“ .- Jlll. a _P. m. _ w. “a T . m a . : ! a I 1...... 1.-.- but; T nun-u . M -.-.—.— .— 0 t i 81!; O" 77 couwwaa>aa nomauumm Hem. .ws< 0H mamsmm umuumo “mm mom. .uamm «N smcmunmmz Monu< caa mama as: HH mam: Hmuumo umm mom. Haua< «N adoaamo HwEom coma um5w5< mamfiom Hmuhmo uwm doma .cww w mflnmc30H nammoa .um camfimnmsoae moo. .uamm OH mamamm newcoEem coxan mesa .uamm H suumm ma..>£mmz mesa umaws< mam: umuumu “mm mom. kua< RN muasoo Goaumooq oumm Mom mucnoo m>mo mama amwwnofiz cw pmum>oomm hxosucox a“ vmpamm .AzoaumUMSDEEoo HmGOmnmm .mH>mm .m .3 “mama .mH>wo paw udonummv kxonucox cw Umpcmn mHHmwOm manomz mo mmflum>oomn cmwwnowz .o mHLMH 78 In addition to these scattered encounters, I mist- netted 10 Indiana bats at four different locations (N19, 20, 22, 23) along the Thornapple River in 1979. Two adult females captured on 17 May were not obviously pregnant. Three other females, however, netted between 6 and 13 July were lactating, while a fourth individual caught on 18 July was postlactating. Along with the adults, three juvenile females and one immature male were taken between 31 July and 24 August 1979. The Indiana bat is apparently reproducing within the study area. Out of 16 M, sodalis mist-netted in 1978 and 1979, 11 were adult females and the rest were young of the year. Most adults were either lactating or postlactating. Lactating females were found as early as 28 June and as late as 15 August. The earliest capture date for a volant immature is 31 July. Humphrey gt gt. (1977) reported that parturition in this species occurred in June and early July in south-central Indiana. Based on the small amount of available data, a similar parturition period is indicated for southern Lower Michigan. Nursery colonies probably do exist in the study area, possibly near the Thornapple River sites, but none has yet been located. All known maternity roosts of the Indiana bat have been found in hollow trees or underneath loose bark (Humphrey gt gt., 1977; A. R. Richter, personal communication). 79 Seasonal Activity Despite its summer residency, M. sodalis does not appear to hibernate in the study area or anywhere in Michigan. The current late seasonal record of the Indiana bat in Michigan is 11 October from Lansing. The earliest capture date is 10 May in Ann Arbor. The available infor- mation suggests that Indiana bats migrate out of the study area, probably to the south, in order to find suitable hibernacula, possibly in Kentucky (Table 6). Geographic Distribution Myotis sodalis is now known fromrfixmzcounties in Michigan (Figure 14). All 25 of the known records of this bat are from thirteen localities in southern three tiers of counties. At the present time, the most northern capture localities in Michigan are Lansing, Ingham County, and Cohoctah, Livingston County (N37). Eastern Long-Eared Bat Myotis keenii (Merriam) Summer Cgptures and Rgproductive Data Only two M. keenii were among the rabies submissions obtained within the study area (Table 2). A male from Kent County was received on 24 July 1975. A second male came from Calhoun County on 18 September 1978. Very few M. keenii were mist-netted during my survey; all were caught along the Thornapple River (N20, 21; Table 80 3). The only long-eared bat taken in 1978 was a male netted on 12 September. The next year, a female with a single fetus was captured on 29 May. Two other M, keenii, a lactating female and an adult male, were snared only a minute apart on 9 July 1979. A juvenile female was taken eight days later. The presence of pregnant, lactating and immature long- eared bats suggests that some M, keenii may reproduce in the area, probably in June. Parturition occurs in late May and early June in Missouri (Claire gt gt., 1979) and during early to mid-June in Indiana (Cope and Humphrey, 1972). Kunz (1971) reports that the median parturition date of this species in Iowa was 27 June and that the mean lactation period was approximately 32 days. Very few sum- mer breeding colonies have ever been located. Mumford and Cope (1964) reported one group roosting under the loose bark of a dead elm tree (Ulmus americana). Another colony used a "small shelter" near the shore of a lake (Brandon, 1961) and one colony has been found in a barn (Cope and Humphrey, 1972). M. keenii is almost always less common than its congener, M, lucifugus (Fitch and Shump, 1979). There is the possibility that mist—netting over streams may bias the results against the long-eared bat. La Val gt gt. (1977) followed 11 light tagged (Buchler, 1976) M, keenii in a helicopter and reported that this small chiropteran foraged mainly in hillside and ridge forest beneath the canopy. 81 Their sample size is small and the possibility that the light affected the animal's normal behavior pattern does exist. If the tentative conclusion of La Val gt gt. is correct, i.e., that M. keenii does not forage over streams, it might explain the consistently low relative abundance recorded throughout this bat's range (Humphrey, 1975). Bear Cave M. keenii was also found swarming at Bear Cave in late summer (see Myotis lucifugus). The long-eared bat is typically less abundant than the little brown bat at many swarming sites (Fenton, 1969; Hall and Brenner, 1968). Occasionally, however, the reverse is true, as at a small cave in Ohio (Mills, 1971) and at a number of small caves in the Upper Peninsula of Michigan (Kurta, 1980b). The activity curve of this species while swarming at Bear Cave is also shown in Figure 11. Seasonal Activity The earliest record in the study area is a specimen taken over the Thornapple River (N20) on 29 May. The latest record is an individual taken at Bear Cave on 8 October 1963 by Jack Mell. The latest specimen, other than at Bear Cave, is the one submitted for rabies testing on 18 September 1978. It is assumed that these bats migrate to available caves and mines for hibernation (Barbour and Davis, 1969; Fitch and Shump, 1979). As with the little brown bat, Bear Cave, the Indiana and Kentucky karst and 82 the Upper Peninsula of Michigan all offer potential winter quarters, but it is not yet known where the long-eared bats from southern Lower Michigan spend the cold-weather months. Myotis keenii is known to be a year-round resident of northern Michigan (Stones and Fritz, 1969). Geographic Distribution Myotis keenii is now known from 21 Michigan counties (Figure 15). The long-eared bat has also been recorded from Isle Royale and Mackinac Island (Burt, 1946). This species is more common in the northern regions of the state, as is M, lucifugus. From north of the 44th parallel, 15.3 percent of the bats submitted for rabies testing were M. keenii, but only 0.4 percent of those from the south were the long-eared bat (Table 5). Hoary Bat Lasiurus cinereus (Palisot de Beauvois) Summer Captures and Reproductive Data Only ten hoary bats were mist-netted in the course of this survey (Table 3). An adult male was netted on 12 July 1979 just S of Vermontville (N19). On 14 July 1979, I cap- tured a juvenile female over the Paw Paw River in Van Buren County (N4). A male juvenile was caught E of Vermontville (N20) three days later. On 19 July 1979, again just 8 of Vermontville (N18), a lactating adult and a juvenile female were taken. Figure 15. 83 Counties from which Mygtis keenii has been reported. Open circlés are counties mentioned in Burt (1946). Closed circles represent new records. 84 4hr 01'?“ «r «If «r «r b v.9 6 .- m .- ..... -_ was-L... "u . M. .- -m r.._.-.--I,-u O .. ...... 1 , .y _ . 1.1171. _ .71.. .W _ a . . . w 1 . *- _-i 3;” -..I.- --.. a .--.!-t . -T-- m _w P“ . . .m _ . __ .. _ . . . _u ..... [.1- +_ 1.... a _-2 .--im . . . ..:; a . .. H _.-L_ .1 3.. . ..... 1.3.. u. u. ..- :}. 7--..--- . . . .. _ . .7. _.. T3. . .. .L.-- .- .... _ ------ . m - ..:: .. . u. ..: m .. . .. -. -_. -...LM 4. .. ha “35. 7.23.3» 'q I I -._._. I l I I T £10011!” OS‘CI-DGU. 85 Captures occurring later in the summer season are all from 1978. Two juveniles and a lactating adult were netted during the night of 31 July - 1 August over the Galien River in Berrien County (Nl). On 18 August, two hoary bats were caught near Okemos, Ingham County (N33); one was a male, but the other escaped before sexing. The last L. cinereus captured was a male taken on 24 August in Livingston County (N38). The only published reference to a Michigan hoary bat in breeding condition mentions a female with two "large" embryos that was captured in Berrien County on 10 June 1917 (Wood, 1922b). There are only a few of these large lasiurines in museum collections. A pregnant female (UMMZ 6055), taken on 5 June 1929 in Ann Arbor, contained two fetuses. I measured the forearm length of the unborn hoary bats at 14.1 and 13.3 mm. Newborn L. cinereus have fore- arm lengths of 16 to 20 mm (Munyer, 1967; Mumford, 1969). Two juvenile females (UMMZ 57728 and 57729) were captured on 14 July 1926 at Ann Arbor; the forearm length of these two immatures was 26.2 and 25.4 mm. Bogan (1972) reports that a 26-day old hoary bat possessed a 28.3-mm forearm. The mist-netting captures and the museum specimens indicate that the hoary bat does reproduce in southern Lower Michigan, probably in June. Parturition of captive hoary bats took place between 4 and 27 June in New Mexico (Bogan, 1972). Whitaker and Mumford (1971) estimate that L. cinereus gives birth in late May and early June in 86 Indiana. McClure (1942) suggests that late June and early July is the time of parturition in Iowa. The hoary bat appears to be a relatively uncommon species in southern Lower Michigan, but my mist-netting procedures may have been slightly biased against L. cinereus. There is some evidence that this solitary tree- dweller is a late forager, with activity peaking within the fifth hour after sunset (Kunz, 1973). If this is true, then the hoary bat may be under-represented in my mist- netting samples since I generally ceased my own activities at four hours past sundown. Lasiurus cinereus, however, is considered uncommon throughout most of its range (Barbour and Davis, 1969). Seasonal Activity The earliest record of a hoary bat in southern Lower Michigan is a female (MSU 13287) found on 21 May 1968 in Oakland County. The earliest record for the state, how- ever is a hoary bat caught on 10 April 1968 in Grand Traverse County (W. C. Scharf, personal communication). There are a number of specimens taken in southern Lower Michigan from October (UMMZ 42161, 51379; MSU 23106), November (Bowers 2; aL., 1968) and December (Wood, 1922a). These late records are surprising since Findley and Jones (1964) suggest that most of these lasiurines have already migrated south, possibly out of the United States, by mid- autumn. Since no other hoary bats are known in Michigan 87 before April, it is still questionable whether these bats can withstand the rigors of a northern winter. Geographic Distribution Lasiurus cinereus is now known from 24 Michigan counties (Figure 16). The hoary bat has also been reported from South Manitou Island (Scharf, 1973). Red Bat Lasiurus borealis (Mueller) Summer Captures and Reproductive Data The red bat is a common species in southern Lower Michigan (Table 3), and yet I never netted an obviously pregnant female. Lactating individuals were caught on 18 July 1979 over the Thornapple River (N20) and on 2 August along Mill Creek (N6). The earliest I captured volant young was on 24 July 1979 near Vermontville (N20). Drake (1957) observed a blue jay attacking a female red bat with "nursing young” on 15 July in Kalamazoo County. Wood (1922a) mentions that a female L. borealis with "attached young" was found in Ann Arbor on 12 June 1902 and 10 June 1908. Dice (1927) describes females with "clinging young" being found in Washtenaw County on 4 July 1921 and 11 July 1926. The forearm size of 17 juveniles and four fetuses that were obtained in Washtenaw County on various dates halisted in Table 7. Since most adults have 88 Figure 16. Counties from which Lasiurus cinereus has been reported. Open circles are counties mentioned in Burt (1946). Solid circles represent new records. 9O ~.m~ 2 onH sane «a omaam o.~m 2 com. sash o nmaoaa m.- a mmaa sane m .mamoa H.mm .H.Nm .o.wm z .m .m HNmH same a oaamm o.a~ m wmma mash 0N osqow NNmH .mona mm. o.mH a mmma mane NN Ramos Rama .moaa mm. o.ma a mNaH mane NN cameo amaa .mona mm. N.wH z mmmfl mash NN mamas N.Hm z mama mane ON qqamm a.~m m waaa mash om mqamm mNNmH .uooz mm. “.mH .o.qa z .2 woo. maze NH mammn momsumm muons: 0.0. .H.OH .m.OH .H.HH . mmma mash NH ommmm mNNaH .uoos mm. H.eH .m.qH .m.sa a .m .z moaa mash on oaamm unmafioo AEEV nuwcmq ahmmhom Now muwn § N22: .mmOHOON mo Esmmsz Gmwanowz mo muwmum>flcs onwlmo cowuomaaoo msu a“ Son mam mucsoo Bocmuammz Eoum poawmuno mHHmoHop mdnnwmmq undumEEH paw Hmumm .m manme 91 forearms in excess of 38 mm, it is doubtful whether most of these young bats were volant. Based on the few mist-netting captures and on the museum specimens, most red bats apparently give birth dur- ing June in southern Lower Michigan. Kunz (1971) estimated the median parturition date in central Iowa to be 15 June and that the lactation period averaged about 32 days. Whitaker and Mumford (1971), working in Indiana, also found that most births occur in June for the red bat. Sex Ratio The adult sex ratio in southern Lower Michigan appears to be disproportionate. Prior to 16 August of both years, I netted 19 adult male L. borealis and only six adult females. This is significantly different from an expected 50:50 ratio (Chi square = 5.76; d.f. = l; 0.01 < p < 0.025. LaVal and LaVal (1979) reported 70.2 percent males in net- ting captures from Missouri, while females were more common in Louisiana. Other regions with a predominance of females are central Iowa (Kunz, 1974), Indiana (Whitaker and Mumford, 1971) and southern Illinois (Layne, 1958). Such unequal ratios may be explained by differential timing of seasonal movements (Kunz, 1973) by "regional differences in foraging behavior of the sexes or regional differences in relative abundance of males and females (LaVal and LaVal, 1979)." That the disparity between numbers of adult males and females in Michigan is not the result of a biased sex 92 ratio at birth is suggested by the ratio of 8:9 seen in the juveniles of Table 7. Seasonal Activity The earliest record of the red bat in Michigan is a female that was captured on 30 April 1919 in Ann Arbor (UMMZ 53090; Wood, 1922a). The latest record for the state appears to be "one taken in November, 1917" in Washtenaw County (Wood, 1922a). There is no evidence that any red bats attempt to overwinter in Michigan. Geographic Distribution Lasiurus borealis is now known from 42 Michigan counties (Figure 17) and is apparently common throughout the state. The red bat is also known from Isle Royale (Nichols and Stones, 1971), North Manitou Island (Burt, 1946; Scharf and Jorae, 1980), South Manitou Island (Scharf, 1973), South Fox Island (Hatt pp aL., 1948) and from Charity Island (Burt, 1946). Silver-Haired Bat Lasionycteris noctivagans (Le Conte) Summer Captures and Reproductive Data The silver-haired bat appears to be a rather uncommon resident of southern Lower Michigan (Table 3). Only four L. noctivagans were captured in the course of this study; all were taken along the Thornapple in 1979. The first 93 Figure 17. Counties from which Lasiurus borealis has been reported. Open circles are counties mentioned in Burt (1946). Solid circles represent new records. 94 iilll ' “I 81‘ n “In. . “‘2 S“PE“‘0“ ._.___ .“I _'— _- . ( .4...— rmrm ' — —.'— _. __ _. . “lad “'56 . -{fl‘l L.-- -.J I _._1._- Cu- 95 silver-haired bat netted was a near-term pregnant female caught on 18 June (N20). A lactating adult was captured on 12 July (N19), while an apparently non-reproductive female was obtained on 19 July (N18). The only juvenile netted was a female caught on 4 August. A.(3.Ruthven captured a pregnant individual (UMMZ 53918) on 13 June 1910 in Ann Arbor. Although Wood (1922a) described the embryos as "large," I found them to be poorly developed with a crown-to-rump length of about 9.7 mm. The only other pregnant female known from the study area was received by the MDPH for rabies testing on 8 June 1979. It was captured in Ottawa County and contained one small (6.2 mm crown-to-rump) embryo in the right uterine horn and another, partially resorbed, in the left horn. The presence of pregnant, lactating and juvenile individuals does imply that at least some L. noctivagans are born in southern Lower Michigan, probably in June. Bailey (1929) reported a lactating female on 9 July in Minnesota. Kunz (1971) caught pregnant L. noctivagans as late as 21 June in Boone County, Iowa. He netted lactating females from 21 June to 24 July, while postlactating adults were captured as early as 22 July. Median parturition date was estimated to be 16 June. There is no record of silver-haired bats reproducing in Indiana (Mumford and Cope, 1964). 96 Parturition and Description of Young Silver-Haired Bats There is apparently neither a published description of the birth process in L. noctivagans, nor is there any information available on the deciduous dentition of the silver-haired bat. Because of the paucity of information concerning L. noctivagans, I feel it important to record my observation of parturition in this species. On 18 June 1979, at 2145 hours EDT, a female silver-haired bat was mist-netted over the Thornapple River (N20). The obviously pregnant animal was confined in a wire-mesh laboratory cage beginning at 0300 on 19 June. On 20 June 1979, at approximately 1530 hours, the animal became restless, wandering aimlessly about the cage and occasionally squeaking. At 1600, she assumed a head-up position on the side of the cage and the first young began to appear. The birth was breech with the left hind foot being the first structure to emerge. This newborn, a female, seemed to actively help in the birth process by pushing against the mother with her hind legs. Birth was completed in 23 minutes at 1623. The mother licked her offspring frequently, often in apparent response to the juvenile's high-pitched chirps. The young female quickly found her way to the mother's left nipple. At this time, the umbilical cord was still attached to the placenta which had not yet been discharged. The posterior tail vertebrae of a second neonate began to emerge at 1630, seven minutes after the birth of the 97 female. This newborn, a male, did not push against the mother and in general seemed much less active than the juvenile female, despite frequent licking by the mother. The right forelimb of the male was entangled in the umbilical cord at birth and physically prevented him from reaching the mother's right nipple. At 1707, the mother, with the male clinging to her, began to walk across the bottom of the cage. The young female, however, had remained attached to the side of the cage by her hind feet. The resultant tension on the female's umbilical cord apparently drew the placenta out of the mother. The placenta of the male was expelled by contractions approximately one hour later. After delivering the placentae, the mother ignored her offspring and I intervened at this time to examine the three bats. The neonates, including umbilical cord and placenta, weighed about 2.5 g each. The forearm lengths of the newborn female and male were 14.2 mm and 14.0 mm respectively. The total lengths of the juveniles were 44.7 mm and 47.1 mm respectively. The mother weighed 11 g and had a forearm length of 40.0 mm. The bodies of the young bats were pinkish and the wings were mottled with tan and black. The black pinnae were not erect and the eyes were closed. Light hair was apparent only about the lips. Kunz (1971) provides a similar description of a neonate, but his juvenile had a forearm of only 12.5 mm. 98 After examining the bats, I returned them to their cage and only made intermittent observations thereafter. The juvenile male died 93 minutes after birth. When I looked into the cage one hour later, the afterbirth of the dead male had disappeared, apparently eaten by the mother. At 1945, an assistant, K. L. Boyd, placed the young female on the mother in the hope that it might be allowed to nurse. The adult immediately consumed the placenta that still hung from her newborn. The mother then allowed her offspring to grasp a nipple. After this, he never again saw any physical contact between the adult and the newborn female. The young bat appeared to gradually weaken and was found dead on 23 June, about 80 hours after birth. After death, the neonates were frozen and their deciduous dentition was later examined under a 10x binocular microscope. The formula for the male's deciduous dentition was i 2:2, c %l%, p %l%. That of the female was i El; c lil, p ___. A fourth upper premolar, however, was visible through the translucent gum tissue of the female. Apparently the complete formula for L. noctivagans is i %§%, c %}%, p %E% for a total of 22 lacteal teeth. This formula is commonly found in other members of the Vespertilionidae (Vaughan, 1970). 99 Seasonal Activity Four September records (UMMZ 53909, 76417, 76434; AU 465) and four October captures (UMMZ 76424, 79482; WSU 3341) of the silver-haired bat exist for southern Lower Michigan. Although 24 October is the latest fall capture date (WSU 3314), there are three winter records of this solitary tree-dweller in the state. Gosling (1978) reported a male caught near Sturgis,EHL Joseph County, on 13 January 1978. Two specimens in the University of Michigan Museum of Zoology (UMMZ 109696, 109697), a male and a female, were taken on 21 January 1959 in Oakland County by J. A. Fowler. All three of these winter records were found at the edge of, or actually to the north of, the -6.7°C mean daily minimum isotherm postulated by Izor (1979) to be the northern limit of this bat's winter range. After January, the earliest record for the state is 2 May on South Manitou Island (W. C. Scharf, personal communi- cation), but the earliest in the study area is 2 June (UMMZ 88085) from Kalamazoo County. The lack of late winter or early spring specimens may indicate that L. noctivagans is incapable of successfully overwintering in Michigan. Most specimens in collections or among the rabies submissions are from late spring to early autumn (Figure 18). This bimodal distribution of captures for the warm-weather months may be caused by an influx of migratory animals at these times (Schowalter pp aL., 1978). 100 Figure 18. Monthly records of Lasionycteris noctivagans taken in southern Lower Michigan. Data was obtained from museum collections (solids) and from rabies submissions (stripes). 101 -O -|||||| -~ -IIIIII --’ .5 -< -2 -u. !- -= fi l j l I 1 7 (D ID Q (0 N 1- SLVB :IO # MONTH 102 Geographic Distribution Lasionycteris noctivagans is now known from 24 Michigan counties (Figure 19). The silver-haired bat has also been reported from South Manitou Island (Scharf, 1973) and from Charity Island (Burt, 1946). Evening Bat Nycticeius humeralis (Rafinesque) The evening bat, Nycticeius humeralis, has rarely been recorded in Michigan. The first specimen was found on 23 May 1938 in the window of a house in Climax, Kalamazoo County (Burt, 1946; UMMZ 80444). This female did contain two embryos at the time of her capture. Another female evening bat was taken at Ann Arbor on 21 May 1956 (UMMZ 103253). The only other known record is that of a female without embryos received by the MDPH on 2 June 1969. This last animal was caught at Harbert, Berrien County Although one pregnant female has been taken in Michigan, it is still questionable as to whether the species is actually breeding within the state. Nycticeius is colo- nial and does commonly utilize buildings for maternity roosts (Watkins, 1972), but none is known in Michigan. The specimen from Ann Arbor may be the most northern record of the evening bat in North America (see Figure 2 in Watkins, 1972). The Michigan capture localities are shown in Figure 20. 103 Counties from which Lasionycteris noctivagans has been reported. Open circles are counties mentioned in Burt (1946). Solid circles represent new records. Figure 19. 104 105 Figure 20. Records of Nycticeius humeralis in Michigan. Open circles are localities mentioned in Burt (1946). Closed circles are newer records. 106 _. w by a w a D d 1 d a . 909% )0 o +e Q IV w o 111)} n . O n m . ----- m .. a . .. Ll I l Lr I 11‘ ; u . 1 .. .m . . 1P . . . ..:... . .---..---.. . 13:..-an a .-:-+3-1.“ x T--- . m _ .. .., .. _ , .. .. . w - 4. - 1.. .. _ 1. _- = . m _a . - -u- « __ 7. _ _ a .T .q . -.- - 3.. a -.- _. ..: - a . . . _ .. - . -- . . _. L... .. . .--L :m _w a 773-.” ..:. 1.- mm mm m m... u. _m H- .m 0 "m . r - 17.-1 -1 _ - . .w. L. n. .m _u _ _r. T . 1.: 3 Jw mm .wmtl.-..I_-m ....- “I- -- “w . --w-1:;.a .. x a f . .. h. . w _. . .. . - u m _ _x- -- 1. w . . a I I .o. a. m an a t a .. .- N . . 107 Eastern Pipistrelle Pipistrellus subflavus (F. Cuvier) The eastern pipistrelle was first reported from Michigan by Stones and Haber (1965). They discovered a torpid pipistrelle in an abandoned copper mine in Keweenaw County on 14 January 1965. Another pipistrelle was found in a different Keweenaw County mine on 19 March 1980 (R. J. Barron, personal communication, 1980). While examining the collection at Andrews University Museum of Natural History, however, I discovered an earlier record of Pipistrellus in Michigan. A male eastern pipistrelle (AU 124) was captured just W of Stevensville, Berrien County, by J. Belts, on 12 November 1964. To date, these are the only three pipistrelles known from the state. The Berrien County record is interesting because it shows that this species may occasionally find its way into the state from northern Indiana. The Stevensville specimen is approximately 175 km NW of a Wells County, Indiana, record reported by Whitaker (1971) and 180 km N of a Tippecanoe County, Indiana, specimen mentioned in Mumford and Cope (1964). The Keweenaw County pipistrelles, which were found approximately 700 km NW of Berrien County, probably entered the state from known populations in neigh- boring northern Wisconsin (Long, 1976; Greeley and Beer, 1949). The three Michigan records are mapped in Figure 21. 108 Figure 21. Records of Pipistrellus subflavus in Michigan. 109 I 3“_______‘ “NWA : aroma war: 1‘ 1_ ___ ‘ i L —---4 ninth. _-_..'._ _._.4..-,_._1.-. 0:1«17 ‘ nus 0 vs an m an n c , I n ; s ' ' I I ' _._ _-_. ..... _,._' ..... _._... D a a ‘o “'Il +-MII\’5 $_.134.I|l .WMT‘. ta“. . KROHVSIS I ~ - 1 ..nl Dulu- 5.." ' l .. ”use" ‘—._.'.——.L.__' Q m m' _.4 l _--' h l '- °,"..n l L_._. _ __CT_.‘;._. —— ..... ._I._.. ““5 ,- Y ._ _ _. L ..... WW7 cum 7 acne". Q3 Qua-l. PART II FLIGHT PATTERNS OF MYOTIS LUCIFUGUS AND EPTESICUS FUSCUS INTRODUCTION Within a community, animal species often differ in their use of space, food and/or time. Bats are no excep- tion. As a group, the Chiroptera utilize a tremendous variety of foods and feeding techniques. Different species will often specialize on insects, nectar, fruit, blood or other vertebrates (see reviews in Yalden and Morris, 1976, and Gardner, 1977). Even within a particular food group, sympatric species will often preferentially consume dif- ferent food items. This has been well—documented for Neotropical frugivores (Heithaus pp aL., 1975; Bonaccorso, 1979; Humphrey and Bonaccorso, 1978) and Nearctic insecti- vores (Whitaker, 1972; Black, 1974; Ross, 1967; Husar, 1976). Besides specializing in choice of food items, various chiropterans will often forage at different times. Dif- ferential timing of emergence from day roosts suggests different temporal patterns of foraging activity (Erkert, 1978). Kunz (1973) has shown that some bats do have characteristic feeding times and that these times may be distinctly dissimilar from those of other sympatric chiropterans. Reith (1980) has recently suggested that the 110 111 foraging time of Lasiopycteris noctivagans is significantly altered in the presence of Eptesicus fuscus. In addition to species-specific food preferences and/ or temporal activity patterns, sympatric species will often forage in different habitats (Fenton pp aL., 1977; La Val and Fitch, 1977; Bonaccorso, 1979; Jones, 1965). Space partitioning within a particular habitat was first sug- gested by Nyholm (1965). He showed that Myotis mystacinus tended to hunt at a greater height above ground that did M. daubentoni in Finland. Handley (1967) reported that out of 25 species captured in an Amazonian forest, only three were caught equally as often in ground-level and canopy nets. Bonaccorso (1978) also showed that many Neotropical chiropterans exhibit vertical stratification in their flight behavior. This report is an attempt to quantify the spatial use of a flight area by two species of Nearctic vespertilionids, Eptesicus fuscus and Myotis lucifugus. Both bats are known to fly over the same section of stream, and the intent is to identify any interspecific or intraspecific patterns that may exist. Specific parameters that will be examined are the height above the water and the distance from the stream bank. MATERIALS AND METHODS The study site was located about 3.2 km E Vermontville in Eaton County, along the Thornapple River (N20, Figure 1). The stream in this area has heavily wooded banks with maples (Ape; sp.) dominating, but with some oaks (guercus sp.), elm (QlEEE sp.) and cottonwood (Populus deltoides) also present. The site appears tunnel- like with a minimal amount of riparian vegetation extending over the river below 9 m, but forming a complete canopy above that height. Netting took place on twelve evenings, at approxi- mately weekly intervals, from 6 June to 24 August 1979. On 6, 11 and 18 June, a three-tiered netting system (see description in Part I) was used. A four-tiered system was utilized on nine subsequent nights. The nets were about 13 m wide, just spanning the stream. In addition to recording standard data, I also esti- mated the position of each bat in the net. Height was estimated to the nearest 0.3 m (1.0 ft) Using the individual nets and their respective shelves as a guide. Distance from the stream bank was also estimated to the nearest 0.3 m, using small markers attached to the net as 112 113 a guide. All bats were punch-marked and released after examination. Only four bats were recaptured on the same night; data from the second capture of the evening were not included in this report. Interspecific and adult-juvenile differences were tested using the Mann-Whitney U test when both N were less than 40. If either N exceeded 40, the normal approximation of the Mann-Whitney test was used. All Chi square tests were with one degree of freedom and were calculated using Yates' correction for continuity. All statistical tests are described in Zar (1974). RESULTS The position of 21 little brown bats caught in the four-tiered net are shown in Figure 22; 11 captures with the smaller net are indicated in Figure 23. The position of 52 big brown bats netted with the large system are plotted in Figure 24. Figure 25 shows the capture loca- tions of nine Eptesicus caught in the three-tiered net. Most Myotis lucifugus were netted low over the water and close to the river bank. About 48 percent of the little brown bat captures in the large net were under 2.1 m and within 3.2 m of shore. In contrast, only 5.9 percent of the big brown bats were caught in the same area. Results with the three-tiered net showed a similar differ- ence, with 63.9 percent of the little brown bats and none of the big brown bats being caught in this section of the net. Comparisons between species showed a significant difference in flight height (t = 4.06; p < 0.001). The distance from the stream bank also differed significantly between Eptesicus and Myotis (t = 3.38; p < 0.001). Data from the three-tiered system yielded similar results for height above the water (U = 91.5; p < 0.001) and for dis- tance from the shore (U = 83.0; p = 0.01). 114 115 Figure 22. Capture positions of 21 Myotis lucifugus obtained on nine nights betweenf24 June and 24 August 1979. The right side of the diagram representS'mid-stream. Height (m) 116 8.53 O 6.40 O O O 4.27 O O O 2. 13 . e e e ' ee . Q 0 . O O O 0 320 _ GAO Distance trom Stream Bank (m) 117 Figure 23. Capture positions of 11 Myotis lucifugus obtained on three nights Between 6 and418 June 1979. The right side of the diagram represents mid-stream. Height (m) 6.40 4.27 2.13 118 3.20 Distance irom Stream Bank (m) 6.40 119 Figure 24. Capture positions of 51 Eptesicus fuscus obtained on nine nights between 24 June and 24 August 1979. The right side of the diagram represents mid-stream. Height (m) 120 8.53 O . O 0 e e : e 0 e e 6.40 fl . 0 O O O O O 3 e . e e . O C O 4.27 . T e O ’ 0 e O O O O 2.13 —-—L. . . . O . O C 0 3.20 6.40 Distance from Stream Bank (m) 121 Figure 25. Capture positions of 9 Eptesicus fuscus obtained on three nights between 6 and 18 June 1979. The right side of the diagram represents mid-stream. Height (m) 122 6.40 e e e 4.27 e e 2.1 a 0 3.20 6.40 Distance from Stream Bank (m) 123 The larger number of big brown bat captures allowed comparison of adult and juvenile positions. Thirty-two adults and eleven juveniles were caught in the large net between 6 June and 12 August (Figures 26 and 27). The flight height of the two groups differed significantly (U = 242.5; 0.001 < p < 0.005), but an hypothesis of no difference in distance from shore was not rejected (U = 174.5; p > 0.2). Most adults were captured above 4.3 m (Chi square = 5.28; 0.01 < p < 0.025). 124 Figure 26. Capture positions of 32 adult Eptesicus fuscus obtained on eight nights between 24 June and 12 August 1979. The right side of the diagram represents mid-stream. Height (m) 125 8.53 6.40 4.27 2.13 Distance from Stream Bank (m) 6.40 126 Figure 27. Capture positions of 11 juvenile Eptesicus fuscus obtained on eight nights between 24 June and 12 August 1979. The right side of the diagram represents mid-stream. Height (m) 127 8.53 6.40 C 4.27 OT 2.13 J. 0 Distance irom Stream Bank (m) DISCUSSION Based on my data, there does appear to be a differ- ence in flight pattern between Eptesicus fuscus and Myotis lucifugus flying over a stream in southern Lower Michigan. Little brown bats generally travel low over the water and close to shore. Big brown bats, as a group, display no obvious pattern, although few are captured where the majority of the M. lucifugus are caught. My quantitative data agree with earlier qualitative statements. Barbour and Davis (1969) state that M, lucifugus feeds a "few feet above the surface" of streams. Fenton and Bell (1979) estimated that the little brown bat usually foraged within 2 m of the water, often "weaving back and forth in and out of the trees along the water's edge." I could find no previous estimate of foraging height for g. fuscus over water. Whitaker 25 a1. (1977), however, believe that the big brown bat will feed from about 6 to 50 m over forests and roadways. A possible reason for the observed difference is that the big brown bat is aggressively dominant over the little brown bat, forcing the smaller species to fly in an area less utilized by the larger animal. Eptesicus fuscus has been known to consume smaller chiropterans under captive 128 129 conditions (Krutzsch, 1950; Engler, 1943). The big brown bat is also known to dominate the much larger nighthawk (Chordeiles minor) when both are foraging at a localized food source (Shields and Bildstein, 1979). Another possibility is that the flight patterns are related to prey availability. A number of studies have indicated that the little brown bat feeds primarily on Diptera, especially chironomids (Belwood and Fenton, 1976; Anthony and Kunz, 1977; Whitaker gt a1., 1977). Big brown bats, in contrast, appear to prey mainly on beetles (Whitaker, 1972). Perhaps chironomids are most abundant within 2 m of the water (see Coffman, 1978) while Coleoptera are more common at greater heights. Whatever the reason for the described pattern, the little brown bat may be physically more suited to fly near the water and the shore. Farney and Fleharty (1969) have demonstrated that the wing-loading and the aspect ratio of the little brown bat is quite a bit lower than that of the big brown bat. Low wing-loading and low aspect ratio are often associated with maneuverability (Vaughan, 1970). Greater maneuverability would allow the little brown bat to avoid such obstacles as protruding branches and partially submerged logs with greater ease than could the big brown bat. The reason for the intraspecific differences seen between E. fuscus adults and juveniles is also unknown at the present time. It is possible that adults and immature 130 individuals lessen competition for food and/or flight space by restricting their activities to different areas above the stream. 0n the other hand, such a difference may simply reflect the generally poorer flight control by the inexperienced juvenile. Subadult bats exhibit less prey selectivity than adults (Belwood and Fenton, 1976; Anthony and Kunz, 1977). Although Anthony and Kunz (1977) attri- bute this to a poorer discriminatory ability in young bats, it may also be related to their difference in flight pat- tern. In any event, a greater number of juvenile captures is desirable in order to confirm that this difference does actually exist and is not an artifact of the small sample size. I believe that I have shown that interspecific and possibly intraspecific differences in space utilization exist for bats flying over a river. Now that certain pat- terns have been identified, the next step is to design an appropriate field project in an attempt to uncover some of the reasons for the observed differences. Until such a study is completed, any explanation for these differential flight patterns is only speculation. APPENDIX A 131 xmmuo cmmm mmsmamq mawumz m 53 m.o 3H .m summom .um nocmnm m mamcmaawm vHOMmuuHm m ax N.m ma Hm>Hm ooumamHmM anonamo Hoaom 2 Ex o.H NH Hm>fim umumzvaoo gunman muflo cows: Mm ax o.H HH xomuu cm3m mam nammOh .um xmo “Hum 32 ex o.m 0H um>am mama nammow .um comwam apnea mm as o.q m Hm>fim asmm nmmmoh .um comwfim muHSB Mm Bx N.m w um>wm comwwm ouHSB summon .um comwflm muw£3 3m 83 w.¢ u xmmuo Haw: summoh .um mcfluamumcou 32 ex o.m c Hm>wm U003 mauuflq mmmo mawucmumcoo 32 ex o.w m Hm>wm 3mm 3mm cousm cw> 3mm 3mm 2 ex o.q q Hm>Hm 3mm 3mm amunm cm> 3mm 3mm 32 ex o.m m xmmuo m>oq dofiuumm muwmao 9mm m 83 N m N Hm>wm Sofiamw amwuumm mxmo mouse 2 ex o.H H ammnum .3550 Gowumooq «x wafiwwauuummozoa .mmnuaamooa mcauumauumnz .m mqmwm mmmHo wcwxooq mommm3mwsm wunnmummnm 2 ex o.m mm xmmao :oHHHaaum> aouaaao wasnmummnm m as e.o am Hm>Hm mmme wcwxooa moonwao zumm 2 ex o.m 0N um>wm mammmauonfi aoumm maaw>umuuom 32 ex o.¢ mm um>am mammmauosa noumm mHaH>ucoSum> m2 Bx o.m «N uo>fim maaamauona coumm mHHH>ucoauo> m ax w.¢ mm Hm>fim mammmfiuogH Goumm mHHH>ucoEHm> m ax 0.3 mm Hm>wm mammmaHO£H Goumm maaw>uaoEHm> m 83 o.q Hm um>flm mammmauosa Goumm oHHH>uaoapm> m 83 N.m om Hm>Hm oaaamcnonH coumm mHHH>uaoEHm> mm 82 w.o ma Hm>flm mammmcuonH Goumm mHHH>uaoahm> m ax m.o ma xmmuo prmo huumm wGHH3om 3 ex o.H NH Hm>fim cflmflmm Bacounmm3 Hmumosocmz 3m Ex o.q ca Hm>wm camwmm mmamcoq amwuv< 2 Ex ¢.~ ma Emouum 5:500 GoHumooA $2 wcuwwfluuumoozoq Umscauaou r w mqm<fi 133 Hm>wm cousm aoumwaw>fiq couzwflum mm 83 m.q mm um>Hm mommm3mwnm coumwaw>flq nmuoonou Mm ax o.q mm um>wm ommmmamHSm coumwcH>HA nmuooaoo m 82 N.m mm uo>wm mommMBMHnm coumwca>fiq swuoonou m2 ax o.¢ om Hm>am umemo cam amnwcH nonmamaaaaz m ax w.q mm amuse smog amnwcH cosmEmaaaaz m ax N.m em um>am “memo sum amnwcH moamxo m as o.m mm uo>wm Havoc tom amnwcH wawmcmq ummm mm um>nm nmumo com amnwaH wcamcmq “mam Hm 2mmuu GOHHHHEum> mommmsmasm wasnmummnm m 52 w.q om Hm>wm mmmao wcwxooq mommmBmanm wusnmummsm 2 SM o.m mm Emmuum xucsoo coflumooq 2 cowumooa wawuumz vmncwuaou r w mdm¢9 APPENDIX B 134 TABLE 9. Location of Eptesicus fuscus nursery roosts. Roost # Location County Structure* 1 1.6 km S Buchanan Berrien B. 2 11.2 km.W Dowagiac Cass B 3 Pullman Allegan 0 4 Lawrence Van Buren H 5 1.6 km SW Marcellus Cass B 6 1.6 km NE Marcellus Cass B 7 1.6 km E Marcellus Cass B 8 7.2 km N Gregory Livingston H 9 Onondaga Ingham H 10 6.4 km E Williamston Ingham B 11 8 km NW Pontiac Oakland H 12 1.6 km E Adamsville Cass B 13 6.4 km N Stockbridge Ingham H 14 6.4 km N Haslett Ingham H 15 7.5 km E Howell Livingston C 16 Byron Center Kent B 17 4.8 km E Joppa Calhoun B 18 8 km N Jackson Jackson H 19 8.8 km E Goldwater Branch B 20 5.6 km N Constantine St. Joseph B 21 2.4 km E Athens Calhoun H 22 9.6 km SW Mason Ingham H 23 9.6 km SW Mason Ingham B 135 TABLE 9 - Continued Roost # Location County Structure* 24 South Lyons Oakland H 25 12.8 km SE Owosso Shiawassee H 26 9.6 km S Marcellus Cass H 27 6.4 km N Stockbridge Ingham B 28 6.4 km N Shaftsburg Shiawassee H 29 5.6 km E Laingsburg Shiawassee H 30 3.2 km NW Potterville Eaton B 31 4.0 km E Lansing Eaton H 32 Mason Ingham H 33 3.2 km NE Charlotte Ingham H 33 3.2 km NE Charlotte Eaton H 34 1.6 km N Shaftsburg Shiawassee H 35 6.4 km SW Eaton Rapids Eaton H 36 4.8 km SW Williamston Ingham H 37 1.6 km SW Fenton Livingston H 38 12.8 km SE Fenton Oakland H 39 14.4 km SE Fenton Oakland B 40 4.8 km SW Mason Ingham H 41 Byron Shiawassee O 42 Byron Shiawassee O 43 Oak Grove Livingston C 44 Oak Grove Livingston C 45 8.0 km E Hastings Barry H 136 TABLE 9 - Continued Roost # Location County Structure* 46 4.0 km N Decatur Van Buren H 47 8.0 km W Three Rivers St. Joseph B 48 4.0 km NE Three Rivers St. Joseph B 49 7.2 km W Dowagiac Cass O 50 Garden City Wayne H 51 2.4 km S Belleville Wayne B 52 2 4 km NNW Sherwood Branch B 53 8 0 km SE Hudson Lenawee B *Structure: B = barn H = house C = church 0 = other LITERATURE CITED LITERATURE CITED Anthony, E. 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