NESTING AND FOOD HABiTS OF THE LWWED OWL (A550 0705 WILSONMNUS) m REICHW Thesis fer tho Om” of M. S. MECHSGAN STAN WERSKTY Wifiém HoE‘E-i-éay Armstrong W57 .c.\'5 «HL‘ massrmc mm FOOD HABITS or m Lona-m OWL (gm gm WILQONIANUS) m MICHIGAN By William Holliday'Armetrong AH ABSTRACT Submitted in Partial fulfillment of the Requirements of the Degree of Master of Science in Michigan State University East Lansing, Michigan 195? ABSTRACT This study was conducted to determine the nesting and feeding activ— ities, the approximate incubation period, the length of time the young remained in the nest, the types of food.utilized, the amount of food used, and the wintering habits of the Long-eared Owl in Michigan. Two nesting areas and five winter roosting areas were studied in lower Michp igan and approximately 2079 pellets of the species were analyzed. Individual Long-eared Owls have been noted to migrate but part of the population appears to be non-migratory. Present data show no pref- erence of the Long-eared Owl for coniferous or deciduous habitat. Eggs are layed from early March to the middle of June and recorded clutches varied from two to seven eggs. During the incubation stage, the male guarded the nest while the female incubated the eggs. Attentive- ness of the adults to the young increased and reached a maximum when the young were four days old, and then decreased as the young grew more cap- able of caring for themselves. Rates of development of the young were unequal and affected by dominance of one young over another. Young that could fly nearly as well as the adults were still fed and cared for by the adult. Hunting activity of the Long-eared Owl was usually governed by the season of the year and showed seasonal variation. Young owls were fed by the adults and were dependent upon the adults for two months, when my study ended. Evidence obtained during this study indicated that the family may remain together through at least part of the following spring. Strong evidence supported seasonal changes in diet of the Long-eared Owl and indicated that the species takes the prey most readily available. The Long-eared Owl was found to be pre-eminently a predator of mice in Michigan. NESTING AND FOOD HABITS or THE LONG-EARED OWL (ASIO OTU§ WIISONIA§U§) IN’MICHIGAE By William Holliday Armstrong 1 Thesis Submitted in Partial Fulfillment of the Requirements of the Degree of Master of Science in Michigan State University East Lansing, Michigan 1957 5/4 7/ 3'7 j lélaék ACEIOWWS I wish.to express my gratitude to Dr. George J. Wallace for inspir- ation and guidance in this study and to Dr. Don V. Kayne and Dr. T. Wayne Porter for editing the paper. Mr. R. D. Van Deusen, Director of the Kellogg Bird Sanctuary, was very helpful. Support towards this research study was given as an award.by the Frank M. Chapman Memorial Fund. Dr. E.N. Southern, of the Bureau of Animal Populations, Oxford, England. was helpful in correspondence. 1 wish especially to thank my wife for con- tinned encouragement and inspiration throughout the study. Other persons to whom the author is indebted are: The late Dr.‘J. Van tyne, Dr. R.W. Storer, and Mr. Dean Fisher of the University of Mich- igan; Mr. Joseph Engemann of Michigan State'University; Mr. Richard Oleeves. formerly of the Kellogg Bird Sanctuary: and Mr. William Fedore of Jackson, Michigan. INTRODUCTION . . . . . . . MATERIALS ANDIML HCDS . . DISTRIBUTION . . . . . . . BREEDING AREAS . . . . . . Area A . . . . . . . . . Area B . . . . . . . . . WINTER BOOSTING AREAS . . TABLE OF CONTEXTS THE RELATION OF EXVIRONMEET TO THE THE BREEDING CYCLE . . . . Courtship e e e e e e 0 Competitive Calling . Aerial Performance . . Non-competitive Calling, Nest Selection . . . . The Nest . . . . . . . Sex Determination . . . Eggs . . . . . . . . . . Color and Size . . . . Egg Laying . . . . . . Size of Clutch . . . 0 Success of Hatching . Pro-incubation . . . . LONG—BAKED OWL Copulat ion 0 e 0 PAGE \OQOO-C-‘H 14 16 19 20 20 21 22 24 24 26 27 27 27 27 29 ‘6 Incubation . . . . . . . . . . . . . . . . . . . . Period of Incubation . . . . . . . . . . . . . . Evening Activity During Incubation . . . . . . . Male Activities During Incubation . . . . . . . Female Activities During Incubation . . . . . . Pipping and Hatching . . . . . . . . . . . . . . Nestling Stage . . . . . . . . . . . . . . . . . . variation in Age of Young . . . . . . . . . . . Adult Activity During the Nestling Stage . . . 0 Male Activities During the Nestling Stage . . . Female Activities During the Nestling Stage . . Behavior of Nestling Young . . . . . . . . . . . Appearance of Destlings . . . . . . . . . . . . Fledgling Stage . . . . . . . . e . . . . . . . . Adult Activities During the Fledgling Stage . . Female Activities During Fledging . . . . . . . Adult Activity, Sex'Unknown . . . . . . . . . . Male Activities During Pledging . . . e . . . . Differences in Age at Pledging . . . . . . . . Fledgling Activities . . . . e e . . . . . . . . Plumage Development and Appearance of Fledglings Rate Of DGVBIOPment Of the Young 9 e e e e e e e e e 0 Effect of Different Rates of Development of the Young iv PAGE #9 1&9 50 51 51 52 58 60 61 PAGE POSt-fleaglingStageeeeeeeeeeeeeeeeeeeeeco-62 Activities of Young During the Post-fledgling Stage 62 Adult Activities During the Post-fledgling Stage . . . . . . . . 63 Appearance of Post-fledglings . . . . . . . . . . . . . . . . . 63 Summary of Calls . . . . . . . . . . . . . . . . . . . . . . . . . 66 During Courtship . . . . . . . . . . . . . . . . . . . . . . . . 67 During Incubation . . . . . . . . . . . . . . . . . . . . . . . 68 During the Eestling Stage . . . . . . . . . . . . e . . . . . . 69 During the Fledgling Stage . . . . . . . . . . e . e . . . e . e 70 FeedingCalls.........................71 RELATION TO OTHER VERTERBRATES . e e . e e e e e e e e e . e e e . e 72 Vertebrates Possibly Competitive with Long-eared Owls . . . . . . 72 Vertebrates Non-competitive with Long-cared Owls . . . . . . . . . 73 FOOD HABITS — FIELD OBSERVATION . . . . . . . . . . . . . . . . . 75 Hunting Activity . . . . . . . e . . . . . . . . . . . . . . . . . 75 Non-nesting Individuals . . . . . . . . . . . . . . . . . e . . . 75 During the Breeding Cycle . . . . . . . . . . . . . . . . . . . . 76 During Pre—incubation . . . . . . . . . . . . . . . . . . . . . 76 During Incubation . . . . . . . . . . . e e . . . . . . . . . . 76 During the Nestling Stage . . . . . . . . . . . . . . . . . . . 77 During the Fledgling Stage . . . . . . . . . . . . . . . . . . . 79 Durirlg the Post-fledgling Stage . . g Q Q Q o o . Q o o o . Q Q % FOOD HABITS - PELLET AHALYSIS . . . . . . . . . . . . . Pellets Produced by Young Owls . . . . . . . . . . . Contents of Young Owl Pellets . . . . . . . . . . . . Size of Adult Owl Pellets . . . . . . . . . . . . . . Number of Adult Owl Pellets . . . . . . . . . . . . . Identification of Adult Owl Pellets . . . . . . . . . Contents of Pellets of Adult Owls . . . . . . . . . . Pellet Analyses by Other Workers e e e e e e e e e 0 Contents Of Summer PGIIBtS e o e e e e e e e e e e 0 An Attempt to Measure Predation by the Owls Upon a Mouse Population . . . . . . . . . . . . . . . . . Comparison of Mice Tagged and Those Found in Pellets In the Same Area . . . . . . . . . . . . . . . . . SUMMARY . . . . . . . e . . . . . . . . . . . . . . . . LI mm 01m 0 O O O O O O . . O C O O O O O O O 0 vi PAGE 83 85 87 89 91 93 95 97 102 LIST OF TABLES TABLE PAGE I. Prey species found in pellets of the Long-eared Owl from nesting and roosting areas, present Study . . . . . 88 II. Prey species found in pellets of the Long-eared Owl by other investigators in Michigan . . . . . . . . . . . 90 III. Prey birds found in pellets of the Long-eared Owl inthePresentStud-ye0.000000oeeoeeoe. 92 LIST OF FIGURES FIGURE 3. h. 5. 9. 10. 11. 12. 13. 14. Some nesting localities of the Long-eared Owl in Michigan . . . . . . . . . . . . . . . . . . . . . . . . Area A in the background . . . . . . . . . . . . . . . . . Area A. the nesting site is Just above the author . . . . A.vegetation map of nesting Area B and adjacent areas . . General habitat of Area B . . . . . . . . . . . . . . . . The ground blind in Area B. Note the density of the pine stand . . . . . . . . . . . . . . . . . . . . . . . The characteristic pose of the adult Long-cared Owl that helps conceal the species so well . . . . . . . . . . . The nest with eggs in Area B. Note the nest composed in part of leaves, presumably left by a former occupant An undisturbed female on the nest during incubation in Area B . . . . . . . . . . . . . . . . . . . . . . . The alert female on the nest during the nestling stage in Area B . . . . . . . . . . . . . . . . . . . . . . . The female on the nest in Area B during the hatching period. A fragment of one egg and the first hatched young are visible behind the egg in the foreground .. . Area A, soaring of an adult over the nesting site . . . e Nestling six and seven days of age from Area B . . . . . . A nestling 13 or 1” days of age from Area B . . . . . . . PAGE . 7 . 10 . 10 . 12 . 13 . 13 . 17 . 28 . 31+ . 34 . #1 . 41 . 1+3 FIGURE 15. A nestling 25 to 26 days of age showing a response t0 Provocations . . . . . . . . . . . . . . . . . . . 16. The adult and three young are on this nest in Area A 17. Nestlings on the nest in Area A. The two young in the foreground are 17 to 21 days of age. The larger is 25 to 26 days old . . . . . . . . . . . . . . . . 18. Anestling seven days of age . . . . . . . . . . l9. Anestling twelve days of age . . . . . . . . . . 20. A fledgling 21 days of age from Area B . . . . . 21. A fledgling 22 days of age from Area B . . . . . 22. Aggressive defense action shown by a fledgling between 30and35daysofage................ 23. A fledgling between 39 and 1+0 days of age . . . . . . . 21+. Afledglin339daysofege.............. 25. Two nestling Long-cared Owls and two Meadow Voles in LIST OF FIGURES thenestinAreaB.o.......... ix #5 14-8 55 56 56 59 65 78 INTROIUCT ION The Long—eared Owl was one of the most interesting of animals. The species has been studied very little in Michigan. with the extent of most investigations being to record the date of a nest and the number of young and eggs. Even these investigations have been few in number. The more extensive investigations in Michigan of the activities of Long-eered Owls have been conducted by Pirnie (1916). Sturgeon (191K)). and Used (1951). Most outstanding of the few investigations of Long- oei-ed Owl pellets in Michigan has been the work of Wilson (1938). Other notable pellet investigations in Michigan include those by Warthin and Van Tyne (1922). Spiher (1933) and Geis (1952). Notable contributions from other states include a nesting study in New York by Whitman (1924), a growth study by Sumner (1929) in California and a life history of the species by Bent (1938). An old and still much quoted record is that Of Doubleday (1898). Important contributions from investigations of other species of owls were made by Mathews (1921) and Southern (1955). Lesser contributions to Long-eared Owl data in Michigan have been made by Brig- he: (19%). Wallace and Black (19%), Jorae (1951), Wickstrom (1953 and Black (1955). I began this study of the Long-eared Owl in Michigan in 1951+ after Dr. George Wallace was informed of a Long-eared Owl roost near the Uni- versity in March of that year. The owls left in the middle of April and during the rest of 19541 found and examined approximately one thousand of their pellets. The following February (with assistance) I discovered another winter roosting area of the species. A.roosting area near Jackson. Michigan.was reported in March, 1955 and.the owls left suddenly while I was conducting a study. Later in March. I was informed of e Long-eared Owl nest near Ann Arbor. Michigan. and investigations of this area were made by daily trips from East Lansing. This same month, Longbeared Owls were observed at the Kellogg Bird Sanctuary in the court- ship stage and.my efforts were turned.there too. Considering the above difficulties. it is small wonder that relatively little nesting informa- tion has been recorded in.Michigan for the long-eared Owl. This investigation is divided into two main parts: 1. A.nesting study of the species; for this data.were collected at two nests in the spring of 1955. 2. A.food study: this included observations during the breeding cycle, and.the data from approximately two thousand pellets of adult Long—eared Owls collected during the winters of 1953-54 and l95h—55 from five different roosting areas. MATERIALS AND MHODS The primary objective of field work was to study the nests and food of Long-eared Owls. Nests and wintering roosts were located by personal searching, and by questioning fellow students and other field workers. *who kindly reported occupied areas. Field notes cover a period of at least 78 hours of observation on #3 different days. Pellets as found at these field locations were sacked and dated for later examination. Field notes were recorded and if possible, photo- graphs were taken of the particular area. Analyses of the pellets were carried out at the‘University. The most satisfactory method.was to break the pellet open by hand, and with forceps and finger tips, dig and sift away every portion of fur or feathers, leaving the bones of the prey. Wallace (l9h8) found.that the skulls of the various mammalian prey were least likely to have been broken in field pellets of the Barn Owl (2239, 31333). and thus were most satisfactory for an accurate count of prey as well as for identification. In the present study. this observation was confirmed by counting all bones in 72 whole pellets. The crania and mandibles were more frequently whole in the pellets than were other bones. The bones most susceptible to breaking were the smaller ones. such as the radius and ulna. Generally, the larger bones. such as the femur. humerus. and pelvic girdle, were present. In one lot of pellets some of the skulls were missing; here limb bones were also counted to determine number of prey. Over the a whole study, however, Dr. Wallace's observation was closely supported. Attempts to locate long—eared Owls during the breeding cycle were made 1w visiting areas in which other investigators reported observing evidence of the birds. If a nest had not been found here previously. the author remained in the area until dusk and listened for the call distinctive of this species. The calling was indicative of the approx- imate nesting site. Two nests were located in this manner. After a nest was discovered, four different techniques were used to study the Long-cared Owl family: 1. moving around throughout the nesting area, listening for calls, watching the nest and the adult birds; this technique was valuable in locating a probable hunting territory of the adult female. observing courtship displays. and incubation intervals; 2. observing the nest continually throughout a day or night from either of two blinds. one on the ground and the other in a tree: this technique was useful during the late incubation stage and early nestling stage when the female was never observed off the nest and appeared to be re- ceiving food from the male: 3. climbing up to the nest and examining the eggs or young to determine the stage of development; this technique was important in determining the exact time of hatching, in observing and measuring the young to determine their rate of growth, and in observ- ing various forms of behavior of both young and adults: and it. listen- ing for the feeding calls of the young Long-eared Owls to locate the family for further surveillance: in this way. the rate of growth of the young owls could be followed and their behavior could be observed for a ,..: '3 I! (A time after they left the nest. hall mammals were live-trapped and marked in conjunction with one meeting study where the author attempted to measure the rate of feeding of the Long-cared Owl family upon a population of its prey. Live traps were set in the vicinity and were visited twice a day, when possible. If animals were caught, the procedure was as follows: the date and place where taken were recorded: if a mouse. the individual was tagged (if not previously tagged) and released where caught. In notes mice were identified as to species (the exception being W sp. caught at the beginning of the trapping period). ear and tail measurements and sex were recorded along with tag numbers. Traps were usually baited with corn and apple. The mice were tagged with fingerling fish tags (No. 3) in the skin over the back of the neck. This location apparently afforded least opportunity for a tag to be lost. He instance of loss of a tag was observed. Notes and photographs were made concerning other animals found in the area and also in studying types of vegetation. DI STRI HJTION The distribution of the Long-cared Owl over North America has been described by Bent (1938). He delimits a wide distribution over nearly all the united States and over the timbered regions of Canada. includ- ing the tree belt along the streams on the western plains and even on the deserts. He describes the breeding range as extending north to Saskatchewan.and Nova Scotia. south to Sourthern California and.Missouri, west to California and British Columbia. and east to Maine and.New Jersey. For’Michigan. Fig. 1. shows the nesting records which were found for the years between 1938 and 1955; these include nests from this study. Nests have been observed in the following localities: Rose Lake. Clinton County (Rose Lake Experimental Station notes) Baker Sanctuary. Eaton County (Brigham, 1996) Kellogg Bird Sanctuary, Kalamazoo County (Pirnie. 1943 and author‘s study) Ypsilanti and Stony Creek, Washtenaw County (Sturgeon. l9hO and author's study) Monroe County (Wallace and Black, 19%) Grass Lake. Missaukee County (Jorae. 1951) Imlay City. Lapeer County (Wicketrom. 1953) Linwood. Bay County (Black. 1955) Mt. Pleasant, Isabella County (Black. 1955) 5 The distribution of these nesting records is shown on Fig. 1. Wood (1951. not included in the records above) described nests of the Long- eared Owl in Monroe County. Ann Arbor. Jackson County. Barry County. and Kalamazoo County: and the most northern of Wood's records. a nest in Eldorado, Crawford County. Few data have been published concerning the migration of the Long- eared Owl. Some early dates of spring arrival north of the regular ‘winter range. as described.by Bent, extend from March 3 in Rutland. Vermont to April 18 in Osler. Saskatchewan. Some late dates of fall departures from regions north of the regular winter range. as described by Bent. have been from October 1 in Halifax, Reva Scotia to November 18 in Argusville and Marstenmoor. North Dakota. Bent states that there is little published information on times of arrival and departure in regions south of the breeding range. but that in general. the Long-cared Owl arrives in these areas in the latter part of Hovember and December and leaves in late February and March. Bent records two long-distance move- ments of banded Longbeared Owls: the first concerning a bird banded at Rosebud, Alberta. on July n. 1933 and next seen at Layton, Utah. on February 2. 1935; the second record that of a movement from Escondido. California. to Corbeil. Ontario. sometime between April 22 and October 9. 193“. It seems possible that not all Long-eared Owls are migratory. Vhile Wood (1951) noted that banding records indicate the Long-eared Owl to be migratory in at least the northern part of its range. (he cites as evidence a bird banded at Williamston, Ingham County, April 27. 1932. and recovered in February. 1936. at Gladstone. Virginia) the same worker listed several winter sight observations. In the present study nesting sites were observed adjacent to winter roosts. suggesting the possibility that the same birds used both. M/55AUK E on-o 514k: BAY < fi (in-wool ' 1548511 OM . Phone | 0 AI». GRATIOT mm . U 0 IV , a. Rose Ink 1; ,4 TOM odelcer S at. 7 .il/ofidn-JS ‘ e. (AM/4:00 M u nesting localities observed by author 0 other recorded nesting localities 0 Figure 1. Some nesting localities of the Long-cared Owl in Michigan BREEDING AREAS The Long-eared Owl in Michigan seems to prefer neither coniferous nor deciduous type nesting habitat. In this and other studies. nests have been found in white pine. scotch pine. tamarack, red maple and elm. While Wilson (1938) noted nesting in a distinct hardwood habitat. the present study, (1955), records two different nesting areas in stands of white pines (21m gtrgggg). Other recorded nests of the Long-eared Owl include one found in Tamarack (£31; 19333133) and one red maple (Age; M), both at the Bose Lake Wildlife Experimental Station in Clinton County. Michigan. (Rose Lake Experimental Station records). Pirnie (1943) reported two nests and Sturgeon (1939) reported one nest. all three in Scotch pine (slim gzlvggtrig). Brigham (19146) found a Long-eared Owl nest in an elm (311411;; 52.) at Baker Sanctuary, Eaton County. Michigan. Area A. The first breeding area studied. designated as Area A. covered 1.7 acres. lying 13 miles south of Ann Arbor. Michigan. and three-tenths of a mile east of 11.8. Route 23. It consisted of a dense stand of white pines (13.133: 331.9211) averaging 3040 feet in height. D0ad branches ex- tended out from each of the trees within the stand. from ground level to about three feet above the ground. Investigation of many spots in the stand could be made only by crawling. The vegetation surrounding this stand of white pine was chiefly grassland with open grassland on two sides and an orchard on the other two sides. In the orchard. grasses were abundant beneath the fruit trees and suggested a savannah type vegetation. mus. the site in which the Long-cared Owls stayed during the day consisted of an "island stand" of white pines surrounded by grassland over which the owls hunted at night e Area ,B The second breeding area studied. designated as Area B. was in the northwest corner of the Kellogg Bird Sancturary. (Fig. 1+). Area B con- eisted of a dense stand of white pines (2L!!! gtrgbug) and occupied an area of about 30 to #80 yards. The trees within the stand were estimated to be 140 - 50 feet high and varied from six to eight inches in diameter. Just as was true in Area A. it was difficult for a person to move around within the stand because of dead branches extending out from the base of each tree. Au oak-hickory woodlot was adjacent to the entire western border of the stand. The oaks (Quercua sp.) and hickories (9am sp.) were estimated to average 60 feet in height. Cover was found only in the crowns of the trees or in those young saplings which were occasionally covered by vines. The oak-hickory woodlot extended East and West some- thing over 50 yards but then gave way to smaller and a greater variety of trees and shrubs with a greater variety of species. About 50 - 75 yards beyond this began cottages and lawns around Gull Lake proper. Figure 3. ' fiirml'v xi’t‘fi‘i‘ddkfl ....M.. Area A, the nesting site is Just above the anther. 10 11 Several large brush piles were found in a large gravel pit in this same area. The oak-hickory woods continued southeast of the gravel pit for about 250 yards and then dropped very suddenly to a lower level along its southeast facing slope. Area B was bounded along its entire eastern border by a steep slope 50 yards wide. A comparatively thick growth of small trees was found here and included staghorn sumac Cm typhing). large-toothed aspen (2m Wain). black cherry (inland amines . trembling aspen WW1). and red cedar (insinuate mam}. Grasses and weeds were abundant along the slope and in the basin. The vegetation changed at the base of the slope where thick stands of white spruce (21.21% m) were prevalent. The spruces. which were 20-30 feet tall, provided the thickest cover available in the Kellogg Bird Sanctuary. A large cultivated field bounded Area B on the north. and was cov- ered primarily with clover W sp.) and alfalfa (24m sp.). The lower. northern part of the field contained two small swales with a dense stand of shrubs. A large swale. 150 by 200 yards. was situated about 100 yards northeast of Area B. Other cultivated and uncultivated fields lay still farther north. This. Area B resembled Area A in being a thick stand of white pine. but differed in being continuous with other wooded areas, with contiguous and interspersed grass lands. er-YV yr 7" E“! “I, Vt7u I] r r t I ““I I“/ u'“ “'u'# “I" W'” "'1 V" rv f 31:: t z: :t 00 ""0 ’0‘“ U . (5?: “ ”a? «w‘ w 7"“: W ', «~- :: .. "'mr: : : r; :m: w , ‘ gin m «w n», M "’"a '1" v" w :: arr! v r ~Y'H, 1L, ' ,r‘ \JI t-l mu". JV 0, rrvertflr'V'rvryvr , 1 . (\LVQ' \ \ ‘ ’ "11'7” nuts, n .vr r v y I’ 7 v T r V r V 7 yr t Vr “1"“. k t I r’ \wo‘l ‘0’“! *‘I'l J'”" “y ll '7 .'::3r'75:53;"":{;i'r; M ,v, t ‘7 -' FEQ” WI um W w W, wlw, at: 'rfi'HH'VUHHV'HJLu,’\ <. " '43“ W W. .3” w "a It 'v VY'7" ' r,vr ," (L ‘ s. 5C“ ""I I" V wm '- rtrpvvvvvvrr::::rvyw We 3 ,V- t‘i i£j " “'1' ‘W’ ‘WI. My W] I WI / WI“ "T rtvrvrvYVY"'rr' vr’V" t if. an. ('“sé — m “I M ‘u "I w” ‘1‘ “OI- n ;':':::::I$mr "WM“, ( t at“ ’ ' '” av" :: ' r v: v v YV” ' '1 3‘“) ‘1 ‘J‘ I r :Yf;;iy.:rr::;' yyr::&w”’. 61",} [Wt WI W/“y \W ml “v: W t: “3:331:13? Wm: m3. '47 ~. NW I WWW “Q "I #3 W WE. TV g”; I"); ' :':' :: it: I '3: Vvvvv \; v , , I t." [vi/w w, \W‘ I /M/ “IF U" W W w ; "U/ m :izvvvvv:;v:v:' a" - pngIJ V// "6 ‘W‘ l" W” W/r W1 will” WW : (”bl ‘m “M. M“! “41/ nW/ .lL/l 3-:ng W’Z/ “'0 ‘V “W; "I, W‘WIW/I' I m ' le: "I v“ ' Mt WU WI! m." €312?ng I W \ “' my‘ “W “p . “H “" M "u ' WW mm v \W: w “I!" i . , \ My W, W I' a... ' ' v V‘ \“I’I \ l/ “H" i . '(k‘ l \\w W \ I‘ I ‘m I we» [I , W/ w a... «I tip, . “II/U/ l - “(I/U “MA/I, 9’ .1} (¢ ‘ "M V” “\M’ W‘ vrvr aeaaaalaaannn .1- ' K .1. 5 a .s an at a: as a as a at .3“ . ff a? ' .m m” to, . -"~ %%30 [WA " a, W. . g) A (i g £039.13“ 8 W’ r j . 5&1 \ ulm mu 4 " "I II'/ M m 61> & fl. 9’ 0M3 L w \ _~ I ' .59 1 ° :1 -" ”'1’" .2“ t . :2 g 3 JD ‘9’ -. uul VIII 1. ‘ ' '9' t”‘ , \W ‘ at al- ‘2. p. 55 9» 0» .1 .1 J a &&&3&&&&&&$&. '“q' P) uh I" u"! A . u‘ L ngtg&fi& £6“, , Ii ,4 ’J‘ o 9’ —‘ 'N am W 3 g, 3) & g) & & $ 99 £3 W: “III ~ \ “I“ .h M t ~ g, as a it .9, a .ng u n. it . s’ w w , at as and; up. a ‘ a s 9» a» a 4% v J, ‘ A 5m, . '9? " r— n. ' & 8) (953‘ (g Lg, w/ .5; ‘3. r , (8/; at 3» 09,319. W t - ' , " d Cf :3 {a {2' r3 1 \ \Sr’d" £358? ‘2' I" ‘ - K ( u" ‘3: [6,5 If. ’I 0 ’Jr ’ p . , : I - I \u , 1, " > ' oi. i m ‘ \o \ {5% 0,, 1» x. (5 DGW‘Q: 65:” 1 WI . If/‘I’fj/J .. {‘- 11 , . qu‘}? a S». 11““ first a, s u my c )0 ‘. *1. Jo ~ . 7c V. ‘A Um: O .. ’3 w :‘u “I ( é: .- ‘ t "u:- \th w, k {5’ V' cfo) . ‘ " ‘ ‘ 4:2' q (‘ u" ‘1‘ ‘1 I l 4. ‘0', . fi 4‘ r" J“ scale 294 yarxs it Me 10;, ‘ l n_ l ,4 e ‘ ‘1‘ nuke 11““ " cultivated \r r r v marsh 4;; ML Glover and alfalfa fl A6808 overgrown - woody plants < .du/ pm (:7 grazing. grasses sparse w" "w woody plants > O 0 “MI grazing, grasses medium H” ’W thickets C) a 0 0 general non-grazing “In u\.I//. deciduous woods grasses thick W, "W coniferous woods A A 4* Figure It. A vegetation map of nesting Area B and adjacent areas General habitat of Area B. Figure 5 . ote the density of N Area. B. din The ground b Figure 6. the pine stand . e" A 11+ . WINTER BOOSTING AREAS Wilson (1938) found winter roosts of the Long—cared Owl in Michigan only in coniferous stands. The present investigation confirms this gen- eralisation, the five winter roosts investigated all being in coniferous stands. 1. The first Long-cared Owl roost made known to the author was sit- uated in Lansing township, Ingham County, Michigan. Approximately twelve owls were present in November. 1953. and fourwere seen the following March. A The owls disappeared during the middle of April. The Lansing winter roosting area consisted of two Norway Spruce-White Spruce groves. one measuring 100 by 20 yards and the other approximately 100 by 650 yards. The small grove was adjacent to a house and yet was preferred for roost- ing. Here conditions existed which were similar to the dense undergrowth already deecribed for the coniferous groves of breeding Areas A and B. In the larger grove spruces grew in a more scattered pattern with dense green branches about the tree bases. extending to the ground. A large field and a beech-maple woodlot bounded both spruce groves. 2. The second winter roosting area investigated was situated approximately ten miles south of Jackson in Jackson County, Michigan. l‘our owls were present when observations were made in hbruary, 1954. Within this area dense growths of tamaracks and pitcher plants (mm; mm) grew profusely on either side of a fast flowing. narrow stream. The pellet accumulations were found beneath the clumps of tamarack. Two 15 dense lowland deciduous woods and a marsh, approximately a mile in length and 600 yards in width, bounded the stream. 3. A third winter roosting area was investigated in the middle of March, 195“. This area is already described as breeding Area A. h. The fourth winter roosting area was situated adJacent to breed- ing Area EB, comprising the thick stand of white spmce already described. for this area. 5. The fifth winter roosting area was within the Kellogg Bird Sanctuary. Although Long-cared Owls had hoen observed in the locality during the winter, there was none to be seen when I investigated the roost in larch, 1955. The area lay nearly a mile southeast of Area B, and consisted of a dense stand of white pine and Jack pine (£1,323 W). The trees were approximately eight inches in diameter and 30 to to feet in height. The tangle of dead branches within the stand was again very dense. Ihus. the winter roosts of the Long-eared Owl found in Michigan have all been in dense stands of conifers. This vegetation was the densest habitat available to the owls during the winter period. In the present study roosts were observed. in lorway Spruce-White Spruce and hits Spruce stands. clumps of tamaraclt and stands of White Pine-Jack Pin. and "hi-ta Pime l7 Figure 7. The characteristic pose of the adult Long-cared helps conceal the species so well. 16 THE RELATION OF ENVIRONMENT TO THE LONG-BAKED OWL All parts of the environment of the Long-cared Owl probably have some effect on the owls. However, some features appear to be the more important. The dense growth of the coniferous stands provide most effective concealment for the owls and their nests and protect the owls from the sun, wind and rain during most of the day. The amount of sunlight appears to be most important in governing certain activities of the Long? cared Owl. This can be noted.when evening activity begins at definite times throughout the breeding cycle, usually at dusk; with daytime activ- ity being limited to the nestling period, and hunting always beginning to the west of their nesting or roosting sites. Weather probably limits the activity of the adult female Long-cared Owl during the incubation and early nestling periods. since the eggs cannot survive being chilled and newly hatched nestlings seem susceptible to extremes in the weather. Adults and fledglings did not, however. appear to be bothered by wind or rain. (A.young fledgling, 28 days old, was observed on the night of June 10 in.Area B. The night was cloudy and.windy with rain, yet the young owl showed no sign of being disturbed as it perched in an exposed site on the tip of a pine bough.) The deciduous woods provides protection for young Long-eared Owls. Both the deciduous woods and open field provide hunting areas for the Figure 7. The characteristic pose of the adult Long-cared Owl that helps conceal the species so well. 17 18 adult owls. and habitat for prey mammals and birds and for animal com- petitors. The winter roosting areas seem to provide effective concealment. Few records of winter observation of the Long-cared Owl in Michigan are to be found in the literature. Some authors believe that the lack of observation, here and in other areas‘of the United States, is due to the type of habitat in which the species is found, and to the nocturnal habits of the bird. Bent (1938) has noted, “Probably this owl is much commoner than is generally supposed, especiaflly in the East, where it finds such effective concealment in dense coniferous thickets. The Long-cared Owl. . . spends the day well hidden in the densest cover it can find . . . . . for this reason it is seldom seen and may be common where its presence is not suspected. It is more conspicuous and so seems more abundant in the de- ciduous trees of the West, especially in.winter.' I found the dense growth of conifer stands and the color of the Long-eared Owls helped to conceal the owls almost completely in the winter months. 19 THE BREEDING CYCLE The breeding cycle in Area A was under observation by the author from March 30 to May 17, 1955. Those stages of the breeding cycle which took place during this period included early incubation to the fledgling stage. The breeding cycle in Area B was observed throughout most of its duration and lasted from March 30. when courtship was first observed, to approximately June 16, when the young fledgling had learned to fly quite well. Information on breeding in Michigan is to be found in l? nesting records of the Long-cared Owl. Thirteen .of these records have been reported in the Egg-£1.33 Eggplgr from 1938 to 1955. In addition, I found two nests in 1955, and I have used two unpublished nesting records of the Bose Lake Wildlife Experimental Station bringing the total to 17 records in Michigan in the last 18 years. (Map 2) Seasonal distribution of nests extends from as early as March 5 to as late as June 15 in these records. Wood (1951) reported an exceptionally late set of eggs on May 24, 1889. I observed a set of eggs in Area B which did not hatch until May 14, but the latest set of eggs was found on June 15 by Jorae (1951) at Grass Lake, Missaukee County. An early set of eggs was described by Wood for March 30, 1904. In Area A, the eggs appeared in the nests between March 13 and 15, but the earliest record of eggs comes from Bose Lake in 1943 where four eggs were found on March 5. 20 Eleven of the 17 reported Long-cared Owl nests in the last 18>years furnish reliable nesting data. In 7 of the 11. eggs are reported in April. In 3 of the 11, eggs are reported in March, and in one case. eggs are reported in.June. Thus. eggs are laid in.March, April, or May and hatch in April, May or June. lurther investigations may show late nests to be those of the young from the year before. I found a suggestion that young may remain with the parents through at least part of the next breeding season, for in Area .A approximately four non-nesting owls remained with a pair of nesting owls well into the breeding cycle. Courtship Although I was unable to determine the exact duration of the court- ship period, I observed activity of the Long-eared Owl in Area B on five different days prior to egg laying. The first observation was on March 31 approximately two weeks before egg laying. I observed the following phases of the courtship pattern in approximately the order listed: com- petitive calling, aerial performance, non-competitive calling, nest selec~ tion, and copulation. Two or more of these phases may occur together. Courtship is really one continuous process. Minimise Competitive calling was heard in Area.B on March 31. Calls were similar to those of the Mourning Dove. The owls began to call at dusk 21 and continued at irregular intervals for approximately 45 minutes. A call consisted of lhgg - 2.1.19.9 - m, with an average interval of three seconds between each syllable, and each syllable a short utterance. Al- though sex determination was not considered possible at this time, field notes record calls of individual owls were of different pitches. This‘Vas the only time when Mourning Dove-like calls were heard. Doubleday (1898) described the hooting of the species in the spring— time as somewhat like that of the Screech Owl but more subdued, and in New York, Whitman (1924) found that the hooting in the early spring GOD? sisted of single low hoots, several times repeated. m Pgrfg rmangg Aerial performance of the Long-cared Owl was observed in Area B on March 31 and April 9. Flights were sporadic and irregular and consisted of turning, twisting, diving, and wing slaps. An owl would suddenly disa- ppear in a swoop or dive to the pines, and on several occasions. a cracks ing noise was heard, evidently made with the wings slapping each other. The similarity of these flights to the flights of the Short—cared Owl (Agig,flgmgggg) as described by Mathews (1921) was marked. Mathews des- cribed the species as acrobatic and leading intruders from the vicinity of the nest with astonishing feats of flying, clapping its long wings to- gether over its back, turning somersaults and dropping like a stone to the ground. Bent (1938) described a remarkable courtship flight of the Short-eared Owl where the owl's wings were best together beneath it eight 22 to twelve times in a second or two. In the present study, this rapid 'wing-clapping was not observed in the Long-cared Owl. Here the "claps" were only single beats, never repeated. Pirnie (1943) observed.two long- eared Owls at the Kellogg Bird Sanctuary "stunting”, and thought it perhaps part of their courtship performance. Pirnie made these observations on January 8 and.Judging from his field observations. egg laying could not here started until late March or the first part of April. Thus. if the stunting described by him was part of courtship, then this last activity must last for well over two months. Epprggmpgtitivg Cglling,,ggd Cgpglatigg Non-competitive calling and possible copulation.were observed in Area 3 on April 9. I approached Area B that evening with caution, hoping to catch a.glimpse of a Long-cared Owl leaving its roost. .A large bird was flushed and shortly thereafter, at 7:15 P.M., calling began between two Longbeared Owls. The calling began at dusk and continued between two owls for approximately five minutes. Each call consisted of a single ghpggg. Immediately'after calling, a Long-cared Owl made an investigating swoop of the area from which the bird.had flushed, and landed approximately 60 feet from a nest I had thought was abandoned. It then searched the im- mediate area with quick movements of its head, made another investigating swoop and landed closer to the nest. Finally, it glided in onto the nest. This same owl made very short sounds similar in their rhythm to a ”clucking chicken" while moving around on the nest. After this procedure. 23 it called a high—pitched mm, (identifying it as a female; see section on Sex Determination on this point) intermittently with a softer and lower 17.122: - 11:13 - £911.: repeated. Then the male glided into the area, half circled the tree and gave a wing slap before alighting in the nest. Both owls called soft and low - 1.1111... - Lug - M, repeated and the male left. The female be— gan calling again the whgggog, uttered three to ten seconds apart. Presently the male appeared again in a tree approximately 20 feet away from the nest and called, wh , but on a much lower pitch than that of the female. The female immediately called - mi; - 11g), - Lug, repeated. The notes were repeated very rapidly and sometimes uttered together as m. In Approximately a minute, the male glided partly around the tree and landed next to her. She suddenly erupted with a very loud - 1133, and the male flew off. The female then called more softly. In ten minutes, the male appeared calling again, and the female be- came excited. The male called for two or three more minutes, glided in onto the nest and the same actions already described in the preceding paragraph were repeated again. The male left and all was quiet. The time was 7:45 P.M.. thus the entire sequence of acts happened within a half hour. These activities of the Long-cared Owl were most unique and were never observed again in the entire study. Undoubtedly, the activity shown was part of the courtship process. The author, hidden on the ground, could not observe the pair of owls in the interior of the nest. However, both the frequency of male visits to the nest and the unusual reactions of the 24 female, pointed strongly toward the possibility of the copulatory act. Neat §§lectign Fest selection in Area B took place at some unknown time between March 30 and April 9. Calling between three owls was heard all around the site where I later found a Long-eared Owl nest. Thus, competitive calling could have been the phase leading up to the final nest selection. new Nests have been recorded in Michigan on the ground. at ten feet, and from 20-35 feet above the ground in the past 18 years. 14.59. Sturgeon (1939) reported a Long-eared Owl nest in Ypsilanti, Michigan, 20-25 feet from the ground, Brigham. (19%) found a nest 35 feet above the ground in Baker Sanctuary, and Pirnie (1916) studied a nest at the Kellogg Bird Sanctuary. only ten feet from the ground and built upon an abandoned crow's nest. Two nests were reported at Rose Lake in l9h2 and 19143, the former 20 feet from the ground and the latter 30 feet. “he nests observed by the author in Areas A and B were at heights of 27 feet and 25 feet respectively. The nest in Area A was an abandoned nest of a Crow (Corvus brachyrhynchos) while a Cooper's Hawk W M) was probably the former resident of the nest in Area B. Bent (1938) described the Long-eared Owl as occupy- ing former squirrel, Crow and Cooper's Hawk nest in Massachusetts and nests of the Magpie (2m 3139) in western United States. Most remarkable was a nest of the Long-eared Owl on the ground, described by Jorae (1951). Six 25 eggs were discovered in this nest on.June 15 near Grass Lake in Missaukee County, Michigan. The ground is the usual nesting place of the Short- eared Owl (5,519, We). Bent (1938) reported that Long-cared Owls have been observed several times to nest on the ground in the United States and England; he shows a photograph of such a nest taken in Montreal. Rests of the Long-eared Owl in Michigan are placed at heights ranging from ten to #0 feet according to Barrows (1912). Barrows found that the majority of nests were abandoned Crow's nests more or less repaired for the purpose. The nests of the Iong-eared Owl are of variable size depending on the type of abandoned nest selected for use. In l9h3, a nest at Rose Lake measured 16 inches in total diameter, and.the outside diameter of a nest in.Area A.observed by the author measured 17-20 inches. The measurements of two nests in Massachusetts and one nest in Saskatchewan were reported by Bent (1938). The Massachusetts nest had an outside diameter of 20 by 8 inches, with a cavity measuring seven by six inches, two inches deep. The nest in Saskatchewan.was unusually large, measuring #8 by 23 inches over all and an inner cavity of 10 by 9 inches. Bent also described a nest in.Massachusetts composed of sticks, rubbish. strips of inner bark and.pine needles. and lined.with chips of outer bark and downy feathers of the owl. Thus, in Michigan, the Long-eared Owl nests on the ground.and to a height of 40 feet. In the literature was found one record of a ground nest, one of a nest ten feet above the ground and eight records of nests 20-35 feet above the ground over the past 18 years. The general belief 26 is that abandoned Crow's nests are among the first choice of the Long-eared Owl, and then squirrel and hawk nests. Sex Determination There was a distinct difference in the pitch of the calls of the two adult birds at Area B. This difference, consistent and easily recognizable to the author's ear, was interpreted as a sexual characteristic. the call of the female being markedly higher in pitch. ‘Unfortunately, it was im- possible to confirm this method of recognizing sex, for to have collected the two birds would.have ended the study in midpcourse. The decision to regard the bird with the higher pitched call as the female was supported by field observations. Fbr example, during incubation, the bird on the nest was heard to give the higher pitched calls. Dr. H.N. Southern has kindly commented by letter to the author regarding this ob— servation, "I think you.may take it in the first place that incubation is done entirely by the female, which gives one a very good clue to voice differences“. Further, Miller (1935) stated that the hoot of the female Long-eared Owl is "four to five half tones higher" than that of the male. Thus, the difference in pitch of the calls provided a method for field discrimination of sex between two otherwise almost identical birds. Although.the female Long-eared Owl is known.to be slightly larger than the male (Poole, 1938), the present author could not detect this difference in the field. 27 Eggs .Qslsr.sns.§izs The single egg I examined.was white and nearly spherical, measuring 33 by 39 mm. Barrows (1912) reported the average size to be 33 by #2 mm. (1.66 by 1.28 inches). The average size of 103 eggs measured in the 'United States National Museum was 32.5 by no mm. according to Bent (1938). Extremes in.width from 30 to 35 mm. and in length from 37.5 to 43.5 mm. were found. Sumner (1929) found the average weight of Long-cared Owl eggs in California to be 2#.8 grams, with a range of weights from 21.5 to 27.1 grams. Eggheads: Wallace (1955) stated that although owls usually lay their eggs every other day, in some cases they may skip more than a day between layings. In Area A, egg laying began between March 13th and 15th; seven eggs were laid in 10 or 11 days, with irregular intervals of one to five days be- tween eggs. In Area B, two eggs were layed between.April 18th and 22nd; these hatched less than 2b hours apart. Whitman (1924) stated that egg laying of the Long-eared Owl took place on alternate days in Ithaca, new York. From Pirnie's (1943) data, a difference of five to six days is shown.between the hatching of the first and second eggs, suggesting a like interval between laying dates. £1.22 a: Lutch Altogether I have obtained reliable data on 12 nests of the Icng-eared 28. Figure 8. The nest with eggs in Area B. Note the nest composed in part of leaves, presumably left by a former occupant. 29 Owl in Michigan (see section on Distribution and Fig. 1). One nest had seven eggs, two nests six, six nests five, two nests four, and one nest had two eggs. Thus, the average number of eggs per nest was five, with a range of two to seven. Bent (1938) maintained four or five eggs to be the average number with the range from three to sight. It is possible that the nest in Area B was a re-nesting, since the egg laying took place late in the nesting season and since the clutch con- tained only two eggs. Barrows (1912) stated that like most other birds of prey when robbed of its eggs, the Long-eared Owl will lay a second set in the same nest or renest in the same vicinity. The Long-eared Owl found by Pirnie (1943) evidently abandoned her nest with no indication of re— nesting. §uccggg° 1f Egtchigg Six eggs hatched and one egg was infertile from the clutch of seven eggs in Area A. Two of the young disappeared.dnring the second.week or shortly thereafter. When last observed, one of the birds was 10 days old, and the other approximately 14 days old. Both young owls from the clutch of two eggs in Area B lived 25 days. One died at this age, presumably because the adults did not feed it after the author placed it in a wire-mesh enclosure to collect pellets. Whitman (l92b) in Ithaca, New York, found that five out of six eggs hatched in a Long-eared Owl nest. Southern (1955) found a correlation between the abundance of mice and the success of Tawny Owls (fitri§.§l§22) 30 in rearing young. He stated, "When mice are neither abundant nor very scarce, the owls lay eggs and allow them to chill (presumably because the hen must leave the nest to feed if the male cannot bring her enough prey) or may lose chicks through starvation". Pre-incubation Bra-incubation activities lasted 9 to 13 days. from April 9 to 13 or 22, in Area B. Incubation Pgrigg.gf Incubgtigg The incubation period of the Long-eared Owls in Area.A began between March 13 and 15 and lasted from 23 to 26 days. Egg-laying took place concurrently with incubation. Bent (1938) stated that the incubation period is generally considered to be approximately 21 days for the species. The concurrence of egg-laying and incubation could not be determined in the Area B study. However, evidence suggested a re-nesting, since in- cubation in this nest did not begin until April 18 or 22. Incubation in this nest lasted from 22 to 26 days. Evenigg' Agtivitz 21.11% Incubation The time of evening activity seemed to be regulated by approaching darkness. Activity began in Area B on April lh at 7:18 P.M., and ended 31 at 8:00 P.M. Two weeks later, activity began at 7:5h P.M., and ended at 8:28 P.M. Mal; Agtivitieg During_1ncubation All observations on this point were made in Area B. The interest of the male Long-eared Owl in nesting activities appeared to decrease during the incubation period. For example, the male usually began evening activity by calling, but he did not call at all during the last 13 days of incubation. The duration of calling was variable, with periods of from less than a minute to several minutes and even 15 minutes being re- corded. Each evening during incubation, the female owl left the nest in search of prey. During the first half of incubation, the male remained at this time in the nesting area, and at times flew close to the nest. The male often called for a short time as the female left, and then called.again when she returned. The call was usually a low monotone whggogg. The last time any activities of the male were observed during the incubation period was on the afternoon of June 1. I climbed toward my blind which was situated above the nest and approximately 30 feet away. The female was on the nest. The male owl reacted to my presence with short, soft, highrpitched cries and ended the calling with low monotone ghpgg. He stopped calling, however, before I reached the blind. Although present in the area, the male showed no actions of any kind after June 1, during the last half of incubation. 32 IRE-Eli Activitigg Mpg Igcgbatigg The interest of the female Long-eared Owl in nesting activity seem~ ingly increased during the incubation period. This conclusion was drawn from the frequency of calling and.magnitude of responses to stimuli to which she was subjected.by the author throughout the period. Again, all observations were made in Area B. Although Pirnie (19u3) stated that a female Long-eased Owl would abandon its nest if disturbed too often during the early stages of incu~ bation, neither of the birds deserted in the present study. The female Long-cared Owl was flushed three times during the first half of incubation. The first interruption occurred on perhaps the first day of incubation, then eight days later, there were two interruptions in the same day. The female saw the author close by on four other occasions in early incubap tion. She was flushed five different times during the last half of the incubation period and saw the author on three other occasions. This owl did not desert. The female owl usually was present on the nest during the day. Dur- ing the early stages of incubation, she left the nest for periods during the day; later she was absent only during the evenings when she left to obtain food. She seemed to hunt in a deciduous woods lying west of the nest and approximately 300 to #00 yards away. On one occasion, I made an attempt to examine the nest while the female owl was hunting. The male was in the area but did not call. I believe the female heard the breaking of branches. She gave a high 33 chicken-like call, flew to a perch in an adJacent tree, and called a shrill child-like cry when she discovered me in the tree. She resumed her nightly foray after I climbed down. Normally her hunting excursions would last eight to ten minutes. Generally, she would call from the hunting area. The calls were wh ooo , high pitched and repeated more rapidly than any call of the male. The author had to apply a greater stimulus to flush the female Long- eared Owl from her nest during the latter nine days of incubation than was necessary earlier. During the period, a slap on the trunk of the tree or climbing the tree was necessary to flush her. Attentiveness was even greater as the time of hatching drew closer with flushing requiring even greater stimuli. On May 12, she did not leave the nest until I had climbed the tree and was standing directly in front of her. Finally she flew off and snapped her bill while in flight. On this day, I found two pipping spots on one egg. On May 13, while on the nest, she spread her wings, erected feathers on her back, breast, and neck and snapped her bill. The second egg was now pipped in one spot but as yet peeping was not heard in either egg. MP1 1 sadfiaiahias Pipping was observed on the two eggs in the Area.B nest. No obser- vations were made on May 11. Two pipping spots were observed on one egg on May 12 at 2:35 A.M. Peeping was heard on.May 13 at 11:00 A.M. from within this egg. The other egg was now pipped in one spot. The first Figure 9. An undisturbed female on the nest during incubation in Area.Be Figure 10. The alert female on the nest during the nestling stage in Area B. - 3h 35 egg'hatched.on the morning of May 1h and the second egg hatched on.May 15 in the early morning. Thus, there was a lapse of #8 hours between.pipping and hatching in the case of the first egg in Area B. The first egg hatched at the Area A.nest on April 7 or 8. Nestling Stage w 1'1 t1 inAaaailauns The ages of the young Long-eared Owls in the nest at Area A.were estimated by comparing their wing, tarsus, and total lengths with those of the two young of known age in the Area B nest. The six young on April 19 in Area A.were accordingly Judged.to be of the following ages: 1. one day old: 2, three or four days: 1, seven days: 1. eight plus days: and l, eleven or twelve days. The two young Long-eared Owls in the Area 3 nest had a difference in age of less than 2“ hours. Whitman (l92h) studied a nest in Ithaca, New York, in which five young Long-cared Owls ranged in age from one to eight days. Pirnie (l9h3) des- cribed a nest located at the Kellogg Bird Sanctuary. in which the total age range of five young Long-cared Owls was one to seven days. Thus, age differences of consecutively hatched siblings vary anyb where from less than 2“ hours to three or four days. Total age ranges of siblings have been found by various workers to be from one to twelve days. Adult Litivit lazing 5.11.9. We tli Em Adult activity during the nestling stage consisted of hunting, feeding 36 the young and calling. The adults were observed to be calling and flying, and to be feeding the young (14 days old) at 8:25 P.M. on May 28. This same type of activity began at 7:30 P.M. and continued to 12:00 P.M. on June 2 and on May 20, it was observed first at 12:20 A.M. and lasted throughout the rest of the night. M Activitiga Dung the Nestligg gtge All observations in this section were made in Area B. The male began the morning, before dawn, by calling in soft wails, as‘ghggggg,-.ghggggg. These calls lasted several minutes and were inter- rupted only when he moved to a new position, approximately 50 yards from the last and always near the nesting area. Frequently, (when he seemed to detect something strange in the area) the wails were interrupted with a loud, gruff, m-m-m-m-m-flh. One such call, am, but not repeated, was made when a crow landed momentarily in the owl's territory and called. On May 6, when the young were 6 days old, the male began calling an hour before dawn, and continued at intervals until 20 minutes after dawn. The male began the evening activities by calling. On June 2, he called continually from 7:30 P.M. to 9:25 P.M. with 10 seconds elapsing between individual calls. He later twice flew away, returned, and called for a few minutes after each return. Calling was resumed again by 11:10 P.M. and lasted until 11:25 P.M. The male was present in the nesting site during the day. He was 37 frequently harrassed by Blue Jays and sometimes by Crows. He took no aggressive action towards these birds, but he was once observed to fly away from the nesting site. This action would help to draw potential enemies of the young owls away from the nest. The males maximum attention to the nest and young owls was shown on May 19, when the nestlings were four to five days old. The author‘was climbing to the nest when the male appeared in a conifer 15 to 20 feet away. He squealed and spread his wings, feigning an injury, then clicked his bill. He flew to another tree still clicking his bill. This reaction varied: two days later, on may 21, the male appeared but did not call or react in other ways. On June 2, he gave the alarm call as the author climbed to the nest. The male's alarm call was a gruff - 1u__h - m re— peated one to six times, or perhaps only low, soft wails as 11.1.9.9- Occas- ionally, he snapped his bill. Pirnie (1943) described a similar reaction of an adult Long-cared Owl in protecting a nestling 25 days old. Pirnie stated, "The adult owl fluttered to the ground cripple-like and kept up a rapid-fire assortment of calls and cries". Injury feignings by adult Long-eared Owls has been described by others, in New York by Whitman (1924), in California by Sumner (1929). and in Virginia by Addy (1939). Ms W” tie mm Me 1:..in fleas The female remained on the nest day and night in the early nestling stage in Area B and was not observed to leave the nest until the young 38 were 15 days old. The male brought food to the nest during this time. (see page 77). The tendency for the female to protect the young could be gauged by the amount of aggressiveness shown. This action increased until the young were four to five days old, and beyond this age, it decreased. The nest in Area B showed this behavior pattern more clearly, perhaps because the young were of the same age. At this nest, during the entire nestling stage, the female could be removed from the nest only by force. The chronological development of the behavior was as follows: 1. Only slight aggressiveness was shown by the adult female when the young were one day old. She attacked the author with her feet when flushed from the nest. No further'aggressive action was shown. At approximately this same stage of the nestling period, Pirnie (l9h3) reported that an adult owl remained until Pirnie was within four feet of the nest, then the owl left but without aggressive action. Sumner (1929) described the death of a very young Long-cared Owl in California.which.was knocked out of the nest and killed by the fall when the adult bird departed the nest in great haste. 2. The highest degree of aggressiveness was shown.by the adult female on.May 19 when the young were four to five days old. In the morn! ing, an unsuccessful attempt was made to force her from the nest. A.stick was thrust against the owl's body, forcing her to the opposite side of the nest. After I withdrew the stick, she hissed and lunged back across the nest. In the afternoon, the author remained below. out of sight, and 39 thrust the stick, with a sack tied to the end, overhead and into the nest. The female attacked the stick as I withdrew it, but she went back into the nest. Again the stick was thrust in. This time, when I withdrew it, she gripped the sack with her talons and tore at it with her bill. Then, she flew off. While I examined the young owls, the female attacked seven to eight times, hitting my arm the first time. Between these attacks. she perched in an adjacent pine tree and called in long wails and low and growl-like calls - M - Lug - 1211.- She did not go back to the nest until I left the nesting site. Bent (1938) gives numerous descriptions of dis- play, and remarks, "I know of no bird that is bolder or more demonstrative in the defense of its young, or one that can threaten the intruder with more grotesque performances or more weird and varied cries". Bent also mentions a note from Grinnel and Storer (1921+) telling of a Long-cared Owl which attacked a photographer several times and once inflicted slight scalp wounds. 3. Less aggressive action was exhibited by the adults when the young were seven days old. A stick was again thrust into the nest. The female gripped the stick, backed off the nest, and finally flew away. This was followed by two passes at the author while he was climbing down with the young. less aggressive action was taken when the young were 114 days old. At this time, she left as soon as the stick was thrust into the nest. 1+. The adult was not on the nest the day the young were 19 days old. It was heard calling in the area at 11:50 P.M. and shortly thereafter, flew over the nest while the author was in the tree. no 5. In contrast to the female in Area B, the female in Area A.never had to be forced from the nest during the nestling stage. She flew from the nest when the author was directly below it on May 27 when the young owls were one to twelve days old. She then attacked.the author two times, hitting him the first time on the back, evidently with her wings. The attacks were then followed.up by swoops at the author. She left the nest as the author climbed the tree when the young were 9 to 20 days old, but she did not attack. She called My}; - M31112 - M from an adjacent pine am the author left the area. Reactions of the female owl to being flushed.were the same as described.when the young were 15 to 26 days old. Pirnie (19h3) reported one adult Long-cared Owl at the Kellogg Bird Sanct- uary scolding him from the nest and another adult owl circling overhead while he climbed to the nest. The young in this latter nest were 9 to 16 days old. 6. The adult female was still on the nest in Area B when the young were 19 days old. She helped feed the young when she left the nest at this time. In Area A, an adult owl was still on the nest when the young were 17 to 26 days old. Mfimm Young owls responded to stimuli by bill snapping, hissing, spreading their wings, erecting their feathers, squawking, and attacking with their talons. The frequency of these actions increased with the age of the young, throughout the nestling stage. 41 Figure 11. The female on the nest in Area B during the hatching period.. A fragment of one egg and the first hatched young are visible behind the egg in the foreground. Figure 12. Area A, soaring of an adult over the nesting site. 42 Young Long-eared Owls seven days old snapped their bills when approached and when handled. Whitman (192”) described this same reaction of a young Long-eared Owl eight days old in Ithaca. New York. Young, 13 to 15 days old that were not approached or handled, were usually lying flat in the nest, making no movement. However, a nestling 1” days old did respond to being handled.by erecting its feathers and throwing back its wings in a defensive action. This was accompanied by hissing and bill snapping. Whitman (192“) first observed a young Long- eared Owl with.wings outspread in defense when the young owl was In days old. Ybung owls 17 to 21 days old showed several kinds of activities. They. erected their feathers, spread their wings, and sometimes appeared to attack me crossing the nest by short hops towards me when I approached them. They backed up to the edge of the nest with feathers still erect and.wings spread when I continued to provoke them. One young owl examined, 19 or 20 days old, finally squawked in protest after it was handled for two or three minutes. Young were between 25 and 26 days old before their wings were devel- oped sufficiently to permit them to leave the nest. One individual (25 or 26 days old) immediately jumped out of the nest when it saw me peer- ing in. It floated down.with.wings outspread, bounced off a few pine boughs. and.1anded safely on the ground. It assumed a supine position when I approached it on.the ground and used its talons for defense. The young owl immediately jumped out again after I replaced it in the nest, landing safely on a branch nine feet above the ground. Other young “3 Figure 13. Nestlings six and seven days of age from Area B. ll .‘. see..'...ll..._ "‘ .N! V ‘ " 5-: l 4': Figure 11.. A nestling 13 or 1.1. days of age from Area B. #4 (17 to 21 days old) in the same nest made no attempt to leave. Sumner (1929) found that young Long-cared Owls, approximately 26 days old, were not ready to leave the nest voluntarily and yet they backed off it when he approached. He also observed young lying on their backs in a defensive pose. The literature indicates that much of the defensive behavior of young birds is learned by imitation of the adults and older nestlings. However, a certain amount of the behavior must be attributed to instinct. A young owl from Area B whose eyes had been open only two days snapped its bill as a response to fear or hunger. A captive owl which had been in my possession since age seven days, spread its wings and erected its feathers in a typical fashion. We a: we tli The external appearance of the nestling, from hatching to the time it is ready to leave the nest, is discussed in the following paragraphs. Notes were based upon the two young in the Area B nest and one young from Area A. Shortly after hatching, the young Long-cared Owl was wet, with the feather tracts easily seen. The bill and feet appeared large in propor- tion to the rest of the body. A few hours after this when the young bird became dry, the trunk, head and tarsus were covered with white down. No changes were observed four days after hatching. Five days after hatching, the eyes opened. The iris was yellow. Figure 15. to provocation. A nestling 25 to 26 days of age showing a response 45 #6 Figure 16. The adult and three young are on this nest in Area A. Figure 17. Nestlings on the nest in Area A. The two young in the foreground are 17 to 21 days of age. The larger is 25 to 26 days old. 47 At seven days of age, black feathers had developed at the base of the orbit region, on either side of the bill, and the bird could hold its head erect for a few minutes. At ten days, black stripes of feathers appeared on the back and belly. Eleven days after hatching, the black stripes became more evident. At twelve days, the black feathers in the orbit region had developed on the inside, across the lower side, and on the edge of the outside corner of the orbital area. The breast was light gray. The belly had nine hori- zontal arc-like stripes of feathers and there were two gray tufts on the head. Thirteen days after hatching, over 12 of these arc—like stripes of feathers appeared on the dorsal side and at the base of the wing. Trans- verse stripes of feathers developed in the wing covert region. The tips of the first three to four primaries appeared dark. At fifteen days of age, the orbit region was entirely black. At seventeen or nineteen days. the head was grayish with faint horizontal gray stripes. The back and wings were striped. The tips of the first six to seven primaries were reddish-brown. At twentyhone days, the first eight to nine primaries were reddish—brown.with horizontal black stripes. The tufts of feathers on the head appeared semicircular and each had two transverse stripes. At twenty-three days, the face feathers were colored redsbrown. At twenty-six days, the primaries and secondariesiwere well developed and the rectices were developed, though the coverts, breast and head were still downy. midi“ ‘Ii’VI chi” i. {F' !"'L i" ’ “II I I'II IIHI' I: “III II: '“II’ ‘I'II'IIIII’ II I ‘III I eesevesloizsessvse' .WIII :i'In In! I'IMIIII.'D:i’ - rg III “ ,ILII, III-I‘M W'I‘IIT'EII ..’ :4. III."V Figure 18. A nestling seven days of age. - ‘fit. '3'; Figure 19. A nestling twelve days of age. 48 ’49 Fledgling Stage Adult Activitigg Durng gig Fledglipg m Adult activity during the fledgling stage was characterized by hunt- ing and by caring for the young (all obseivaticms here were made in Area B). During the day, the adults protected the young while at night they hunted food and fed the young. (See Page 7 5 Food Habits). The adults devoted more time to these activities during the earlier part of the period than they did later. Hunting and feeding seemed to occupy about 18 hours a day during the early days of this period, but only about five hours later (8:00 am. to about 1:30 A.M.). Bent (1938) stated that both parents during this period rushed to the fledglings' defense and attempted to lure intruders may by feigning injury, by feigning capture of prey, or by other acts. I observed injury feigning only once, and then by the adult female. 3.325;}. AM V1” DAT-LEE fledging The female owl remained near the nest throughout the first day of fledging (June 3, when the young owls were 20 days old). Earlier this sale day. at 5:25 LIL. she called mug - mug - 3.9.9.212. - _gg_u_h (silent for 15 to 20 seconds). 119.922 - mph (silent for 15 to 20 seconds) w ouh - mu}; - _p_9_u_h from within the nest. Fifteen minutes later, she perched outside the nest and watched the young inside the nest. She called at irregular intervals from 5:1414 A.M. until 9:20 A.M., once calling continu- ously for one and one-half hours during this period. The call was unusual 50 and can be described as 11032;; -- m - 39,1133}. The call changed at 9:28 A.M. to a very soft 3p}; - ml. The same type of calling was again heard that evening, beginning at 7:15 P.M. These were short calls, lasted only a few minutes, and.were heard six different times until 9:30 P.M. Certain actions of the female were observed in response to activities in the area. A black squirrel was in the area at 7:h0 A.M. on June h and it Jumped onto the trunk of the nest tree. The adult attacked the squirrel and within two seconds had knocked it to the ground with her talons. She then stationed.herself at a point between the two young and above them. One fledgling was still in the nest and the other perched approximately five feet away. The adult left this spot briefly at 8:25 A.M. and called from a telephone line. then returned. One of the young fell from its perch at 9:35 A.M. While I was replacing this young in the nest, both adults were in an adJacent pine. One of the adults flew over the other fledgling, which was perched nearby and then flew near me. The female began calling normally again 15 minutes after this incident, although the male was still giving his warning call and the young owl which had been replaced still showed its defiant display. On one occasion when the fledglings were 27 days old, the female called with a shrill child-like cry while the author was still 100 feet from the young. Adult Activity, Se; Unknown At 8:00 P.M. June 11 (fledglings 28 days old), I heard one young calling 51 about 150 feet southwest of the nesting site. While I was still 100 feet to the east, an adult began calling Luh - Lug - in}; and made a gliding flight out over me. The call changed to guorrel - guorre; - m with a rasping quality fifteen minutes after I hid. After dark (at 9:00 P.M.), I tried to find the young owl by investi- gating dense cover in which it could hide. While I was climbing a sapling to search for the young owl in the dense crown of the tree, an adult owl flew to the ground beneath the tree and called a shrill child-like cry. The adult seemed much aroused. I climbed down and searched for the young owl on the ground, but did not find it. Approximately two hours later, an adult was observed feeding the young owl in the same tree. The next morn- ing after searching, I found the young owl approximately three feet higher in the tree than the point I had reached the previous night. Malg Agtivitieg Durng Fleging The male was identified by call during the fledgling stage, on June 3 when at 7:15 P.M. I was replacing a fledgling in the nest and the male began his warning cry mph - 1min - fling. He continued calling until 8:30 P.M. Next, he flew to a perch near my blind, where he gave six calls. separated by long silences, concluding at 9:15 P.M. On six other occasions, the male called in the same manner, but only for short periods. Diffgrenceg in fig; at Eledging The two nests differed in the range of ages represented. In Area A, there was a difference of eight to nine days between the ages of the oldest 52 and youngest fledglings, a range reduced by two days on.May 3 when the two youngest owls disappeared. The difference between ages of the two oldest young was approximately four days. The oldest of these young owls developed faster than its sibs, it may, therefore, have had a better chance to survive. By May 3, no attempt had been made by this oldest young to leave the nest, even though it seemed to be quite capable of keeping its balance. When the author peered into the nest, this young owl immediately Jumped out and floated to the ground unharmed. It was then 25 to 26 days old. The situation was quite different in Area 3 where the two young owls, of approximately the same age, left the nest when 20 days old. The pres- ence of the author and the continuous calling by the female may have had some influence in causing an early date of fledging. Whitman (192#) in Ithaca, New York, told of a young long-cared Owl leaving the nest when four weeks old, after the other young owls had earlier left the same nest. Fl lin Agtivitieg The apparent degree of reluctance to leave the nest varied among fledglings. In Area B, one fledgling moved around in the nest approx- imately 12 minutes before it left, while the other fledgling, 12 to 23 hours younger, moved around in the nest about ten minutes before leaving, then left the nest, and after almost falling, it returned immediately to the nest. It finally left one hour and forty-eight minutes later. South- ern (1955) observed a young Tawny Owl (Strix alucg) in England.which made 53 ° a premature attempt to leave a nesting box, nearly fell, and then returned to the nest, not to reappear for several nights. After the young owls left the nest, the principal activities observed were those of exploring the environment and of expanding the home range. Exploratory behavior was observed more often during the first part of the fledgling period than later. In Area B, young owls first stood on the nest and stared at obJects, then moved their heads in a circular fashion (in a plane parallel to the body) with their eyes fixed on the object. This movement was rather rapid and first either clockwise or counterclockh wise. then reversed. Southern (1955). in studying the Tawny Owl (_S_t_1;i_x_ .glggg) in England. states that because the owl's eyes can sense only mov- ing obJects, this head movement is necessary, to cause stationary objects to move across the field of view. Exploration by the young owls continued, they Jumped down onto lower limbs of the nesting tree or moved further out on the same limb and continually inspected obJects, using the above des- cribed head movement. The young often watched the adults in this same manner. Further development in the young owls was observed about lb.5 hours after the first leaving of the nest, when fledglings, perched on a limb in a squatting position, stood up and stretched their wings outward, demonstrating an improved ability to balance. Still later, the fledglings had moved far enough from the nest so they could not be observed by the author without a careful search for 5h them. At this time, they moved their heads very slowly and kept their gaze upon the author. A typical response of young owls to human.presence was to spread their wings and to erect feathers on their back, neck and breast. Some- times they hissed and snapped their bills. This response was observed in birds 20 days old but was much more apparent in an individual 29 days old. On one occasion, a young owl attempted to escape before responding as described above. In Area A, the author tried to capture a fledgling (30 - 35 days old) which was perched 20 to 25 feet off the ground in a pine tree. The owl Jumped down onto the lower branches and then to the ground, where it ran quite well. A very aggressive reaction was shown by this same fledgling when it was captured and.hand1ed by the author. The owl not only erected its feathers and spread its wings, but attacked by Jumping forward, extending its legs and grasping the author's trousers with its talons. The owl then maintained its position by beating its wings at a fast rate. Movements of young owls after leaving the nest were generally away from the nest site. Southern (1955) made this same observation in studyb ing the Tawny Owl in England. The following observations were made upon this point for the Area B nest. June 3 —-l9 & 20 Days Old lflafiéiiagid lladsliasJE 5:32 A.M. - moved to the nest edge 6:00 Ann. - moved to the nest edge 503.5 nu. - Jumped back into the nest 6:10 am. - was outside of the 5:35 Awu. - moved to the nest edge nest and then Jumped 53M A.M. - moved to a limb back in Figure 20. A fledgling 21 days of age from.Area B. 55 Figure 22. Aggressive defense action shown by a fledgling between .30 and 35 days of age. 56 6:00 6:10 7:25 4:25 7:30 8:12 8:18 8:22 1:00 9:00 9:25 A.M. A.M. A.M. P.M. P.M. P.M. P.M. P.M. A.M. P.M. P.M. A.M. 57 June 3 --l9 & 20 Days Old (contd) by the author . - moved to a position two feet north of the nest of the nest moved further and occupied. 7:H5 a position 100 feet south of the nest and four feet off Fledgligg A Fledglipg J; moved further out to a 7:00 A.M. - stood up in the nest position south of the 7:h8 A.M. - climbed out on a nest limb Just north of moved further and almost the nest into the adJacent tree 9:20 A.M. - same position moved further and occupied. 2:30 P.M. - same position a position five feet south 7:00 P.M. - replaced in the nest P M the ground 8:22 P.M. - moved further to a replaced in the nest by the position ten feet author north of nest 8:30 P.M. — moved further to an adjacent tree moved to a position lying one foot south of the nest moved further moved to a position lying eight feet south of the nest (This bird was en- closed to try to collect pellets: experiment was a failure as bird died somewhere be- tween June 7 and June 9, at 23 to 25 days of age) June 10 - 27 Days Old moved to a position further out and lying 110 feet south of the nest moved to a position further out and lying 175 feet south of the nest and 20 feet from ground level June 11 - 28 Days Old moved further and occupied a posi- tion southwest of nest and #0 feet from the ground level June 12 - 29 Days Old occupied the above position 58 The movement of each fledgling was away from the nest, and once the initial movement out of the nest had been made, there was no return. Possible factors influencing the young during this time includes the calls and movements of the adult birds. 31%; Devglgpmenp and, W g_f_ Elegglingg Older fledglings may resemble adults in appearing very long and narrow as they perch in a coniferous tree. The following description of the young is based upon the surviving bird of the Area B nest and a cap- tive owl from Area A. At 21 days, the first eight or nine primaries were reddish-brown with horizontal black stripes, back and wings striped, and tips of the first six or seven primaries were reddish-brown. At 23 days, the face feathers were colored reddish-brown. At 2h days, the new primary feath- ers were better developed than the new rectrices. At 26 days, the new primaries. new secondaries, and new rectrices were well developed. The wing coverts, breast feathers and head feathers were still downy. At 33 days, the rusty feathers were unsheathed further in the orbicu- 1ar area. A very noticeable white patch of feathers extended from the chin and the gular region to approximately one-third of the distance up the outer perimeter of the orbicular area. A black line of feathers was unsheathed on the outer perimeter of the orbicular area and extended ven- trally to the inside of the white patch and then beCame very narrow and faded out. White lines of feathers had developed on the cranial edge of Figure 23. A fledgling between 39 and 40 days of age. 59'~ 60 the wing at the region of the distal end of the radius and extended dis- tally. When the bird.was 3# days old, the white feathers on the cranial edge of the wing were better developed. At 35 days, rusty feathers cov— ered nearly all of the orbicular area. A.heavy black line of feathers bounded the outer perimeter of the white patch which had developed in the ventral part of the orbit. The rest of the head was downy gray. The dorsal surface of the primaries and secondaries were ten and heavily barred with reddishpbrown. Batglgi Devglgpment,g§ thg Igung All owls did not develop at the same rate. In Area B, the two young Long-eared Owls fledged.June 3 when 20 days old. Development of the two young appeared equal until they were 25 or 26 days old.when one of them died. The remaining young was capable of full flight when it was 30 or 32 days old. In Area A, the eldest long-cared Owl fledged from the nest when it was 25 or 26 days old. It flew well when 39 or #0 days old, while on the same day one of its sibs, between 3h and 35 days of age and no more than eight days younger, was not yet developed to the point where the eldest was two weeks before. Slower development was indicated by a slower development of plumage. Thus, in time to acquire full power of flight, the two young in Area B developed at approximately equal rates, and both faster than the owls in Area A.where the younger owls developed slower than the eldest in the same nest. 61 Effect 91 Qifijgrgpt 3.93.9.3 g1 pgvelgmept 91 .1722 19% Different rates of development of the young long-cared Owls created correspondingly different times when fledglings showed the same degree of independence. The eldest young in Area A.was developed enough by the time it left the nest to maintain its balance in flight and float to the ground or to an adJacent tree. Two siblings and the adult Long-eared Owl were in the nest when fledging of the first young took place. The young in Area B remained in the nest for a shorter time than did the young in Area A. In contrast to the eldest young in Area A, these owls could not float to the ground the day they left the nest. At this time, they used their wings only to maintain balance when perched in the nest tree: one used its wings to aid in Jumping from one branch to another about a foot away. The young owls seemed particularly vulnerable to predap tors at this time, for example, one of the fledglings lost its balance three different times under natural perching conditions. The last observed fall of this owl was when it had been out of the nest for three and one-half hours. This time it momentarily hung by its feet, but finally landed on the ground. The owl was not inJured, it walked away from the nest tree and appeared only curious towards its surroundings. Sumner (1929) in discussing Long-cared Owls in California, stated that the inability of the young to remain in the nest until the power of flight is gained.would appear to be a considerable liability to the species, especially because of danger from predatory animals. 62 Post-fledgling Stage During this stage, young Long—eared Owls flew nearly as well as the adults but were still under the care of the parents. Between June 15 and July 3, I visited Area B six times and observed the one post-fledgling remaining, when it was 32 to 50 days of age. The adults still protected and cared for the young owl, whose development enabled it to occupy a greater home range. Activity of the adults took place concurrently with that of the young, beginning between 8:00 and 8:30 P.M.. and lasting until about 3:30 A.M. I was never present to record the activity around dawn. Agtivitigg 91 m Durng the Po t-flegligg §t§ge During the post-fledgling period, the young long—cared owl was ob- served on four occasions. Activities at three of these times are noted in the following paragraphs. 1. When the young owl was 33 days of age, the author observed it perched on an exposed branch approximately ho feet from the ground. The author threw large objects towards it expecting that it would leave its perch and float to the ground. After several minutes, the owl flew away. 2. The young Long-eared Owl became silent in response to the warning call of the adults when it was 50 days old. The author was listening to the young call and approached the area from which the call was coming. An adult Long-cared Owl called in}; - Luh_ - Luh_ whereupon the young immed- iately stopped calling. The young's only call was a frail squeak, and was not audible to the author for more than 50 yards. 63 3. When the young Long-eared Owl was 34 days old, it was observed making short flights in tree tops and.was heard calling three or four times during the time it waited to be fed. It would disappear into the foliage after each flight, thus the call might serve to inform the adults as to the whereabouts of the young. The young owl occupied a greater part of the apparent home range during the post—fledgling period and.was capable of short flights. It was always observed in deciduous trees during the late spring and summer, within an area 100 to 150 yards in diameter. Adm gtivitigs 211225 pp; {fist—fledgligg flags The activities of the adult Long-eared Owl centered around protection and feeding of the young during the post-fledgling period, when only one adult was observed in the area at one time. The warning call mentioned previously as heard during other periods was heard again during this period. The call was whph - whuh - ghph (repeated). Another type of call was heard twice, on.June 10 and June 15, during this period. This was a soft call and.was normally given from the same perch on a telephone line. The call may be described as whurrr -l!hgggg - whurrr. oe ce‘gf ngt-fledglipgg A.general description of the color of the captive young Long-eared Owl from Area A from age approximately 36 days to age 59 days old follows: 64 At 37 days, the face was rusty; on the outer perimeter of the orbit was located an inner ventral white patch, a median black line and an outer tan line; a white patch extended from the chin and gular region about one- third the distance dorsally to the outer perimeter of the orbit; black bordered the median perimeter of the orbit ventrally and one-half the dis- tance around the orbit, the black then bordered the white patch; light tan composed the outside perimeter of the orbit. The breast and upper abdomen was gray, streaked with brown and some tan. The lower abdomen, crissum, and legs were rusty. The tarsus was white. The anterior edge of the wing at the region of the distal end of the radius was light tan and extended distally to the proximal end of the primaries. The primaries and secondar- ies were light tan with reddish-brown bars; the bastard quill coverts were reddish-brown; the greater primary coverts were light tan and heavily streaked.with reddish-brown: the greater secondary coverts were gray and lightly streaked with reddishvbrown; the median and lesser secondary coverts were reddish-brown. The back was dark tan heavily barred.with brown. The dorsal surface of the tail was tan with brown bars. The top and back of the head was downy gray. At #5 days, a white facial patch extended one-half the distance up the outer perimeter of the orbit. The breast was gray and streaked.with light brown. At #8 days, a.white facial patch extended dorsally and lay outside of a ventrally projecting black margin around the orbit. At 59 days, tan appeared on the head; longitudinal brown streaks appeared down the back of the head; the breast was tan and white, heavily streaked with Figure 21.. age. 8 O . day f g 3 65 66 dark brown in the upper part and lightly streaked in the lower part; and dark brown and black feathers were located in the ear tufts. Summary of Calls The voice of the Long—eared Owl has been described by several authors. Sumner (1929) reported that the adult Long-eared Owl gave forth a series of squeaks and whines, and cried when protecting its young. He said that the young gave loud shrill prolonged squeaks. Whitman (1924) stated that in New York Long-eared Owls gave low pitched.wocks, single low hoots, uttered wild and curious cries when protecting their young, and gave a high—pitched "quick", repeated several times when the adults were greatly stirred. I described this last call on page 22, when I compared it to that of a "clucking chicken". Whitman said this Call turned into a scream when the bird was excited. However, I have not interpreted any of the calls as screams. Addy (l9hO) described Longbeared Owls in Virginia.which uttered calls and cries. Doubleday (1898) observed a subdued hooting in the spring; other calls described by the same author included a soft toned.wuphunk repeated slowly, a low twittering whistling note, dicky - dicky - dicky, and the most common call, a prolonged me-ow-ow-ow much as a cat's cry. Says Doubleday, “. . . . . it would seem folly for a bird that lives chiefly on mice to utter it". Calls of the Long-eared Owls in Area B, as I heard them, impressed me as being a means of communication between the owls during the breeding cycle and thus as playing a most significant role. Supporting this belief 67 is the appearance of different calls in each of the stages of the breeding cycle. According to my data, I differ somewhat with Saunders (1951) as to the importance of these calls. He indicated that owl calls are more frequently used in late summer when nesting activities are entirely over, and, therefore, he reasoned that the calls do not have the significance in mating which a true song is supposed to have. According to Saunders, call and alarm notes of all birds are definite, used under certain specific conditions, and "evidently have meaning”. Although some calls of the Long— eared Owl were nearly like songs, to my ear, certain authorities (See Saunders, 1951) question whether one may classify any of the sounds uttered by owls as songs. Accordingly, I here refer to all of them as calls and list them according to the part of the breeding cycle in which they were heard. Dggigg Cgurtahip Was heard at three different pitches (Page 21). "'\\, 3 sec. “"‘~\\ 3 sec. ““‘\\ whoo whoo whoo Took place between the male and female Long-card Owls (Page 22). ~\_ whooooo Uttered by the female Long-eared Owl while on the nest but preceded 68 the egg-laying period. (Page 23). -‘_—_"‘\\ 3 - 10 sec. “"“-‘\\ whoooo whoooo A. Given intermittently with the preceding call and less than a second elapsed between syllables. (Page 23). B. Took place between the male and female Long-cared Owls while both were on the nest during the possible copulatory act. ——’—_—‘ wuh wuh wuh wuh wuh wuh wuh Given by the female Long—cared Owl while on the nest and appeared to be in anticipation of the male's return during the copulatory phase. (Page 23). wuh wuh wuhwuh wuh wuh wuh wuhwuh Given by the male Long-cared Owl while near the nest and was made to the female owl on the nest. (Page 23). ___.__.\ whoooo Durigg Incubatign Given by the male Long-eared Owl when the female of the species left 69 the nest to feed. (Page 31). whoooo whoooo whoooo The female Long-cared Owl reacted to intruders by giving a high chicken-like call and crying. (Page 33). The male and female Iong—eared Owls called to each other with whoooo—whoooo, as already described in the courtship calls. The calls of the female were higher pitched and repeated more rapidly than the calls of the male. (Page 23). Durigg the Negtligg Stage The male Long-cared Owl began the morning and evening activity with this call. (Page 36). \ 1 whoooo whoooo Two types of calls were given by the male Long-eared Owl when some- thing strange was detected by him in the nesting area. The first was loud and gruff. (Page 36). _’___ ,_.—— If wuh wuh wuh wuh wuh .r/ wuh 70 ‘The male Long-cared Owl sometimes indicated alarm by this low and soft call. .___\ whooo Under extreme conditions. the male Long—cared Owl showed alarm by squealing. (Page 37). The female Long-cared Owl expressed alarm by crying with long wails and calling low and growl-like 1m: - wuh - Lru_h_. (Page 39). The female Long-eared Owl indicated alarm by this call. The call was very similar to the wuh-wuh-wuh call described in the preceding para- graph but was much more emphatic. (Page #0). ” fl bwauk bwauk bwauk bwauk During the Fledgligg §tgge The female Long-eared Owl gave three different calls on the day the young owls became fledglings. The last was very soft. (Pages #9 and 50). 1. —. ..— / / / 15-20 see. / woouh woouh woouh woouh woouh woouh woouh 2. /'/—_ wough—woughwuh—wough 3. \ \ well well 71 An adult Long-cared Owl was observed making this rasping-like Call when the young owls were 28 days old. (Page 51). \\\ quorrel quarrel wuowh An adult Long-eared Owl was observed making this soft call when the young owls were 32 days old. (Page 63). \ \ \ whurrrr whurrrr whurrrr Feeding galls An adult Long-cared Owl gave this soft call when feeding the young which were 18-19 days old. (Page 79). 0—,“. # f" wough wough wough An adult Long-eared Owl gave this hoarse Call in reply to the young and before the young were fed. wuhrrr cha cha cha cha The young Long—eared Owls were noted to call before and during feeds ing. The single notes were soft, short. high pitched or flute-like squeaks. 72 RELATION TO OTHER VERTEBRATE A list of those vertebrates which were observed by the author, and which may have affected the Long-eared Owl included amphibians, reptiles. birds and mammals. Statements concerning the effects of the various an- imals upon the Long-cared Owl are largely speculative; more precise rela— tionships could be established only by further study. Animals classified as competitive are those considered to compete with owls as to food. hunt- ing, roosting, and nesting areas. while non-competitive animals are those which serve as food for the owls. Records of vertebrates in the same areas occupied by the long-eared Owls were assembled from sight records, as from analyses of owl pellets and from records of a small-mammal trap- ping study. Vertebrates P9§§ibly Cgmpetitivg with on -eared Owls As to food: Cooper's Hawk (Agglclte; gooperii). Red—tailed Hawk (Buteg jamaicgngis), Redrshouldered Hawk (Buteg linegtgg), Marsh Hawk (gigggg annegg). Great Horned Owl (Bubg zirginigggs). Screech Owl (£figa,a§;g). Barred Owl (§tr;; varia). Saw-whet Owl (gegoliug acadica , Short-tailed Shrew (Blarina brevngndg), Masked Shrew (Sggg; cinereug). Least Shrew (Cryptgtig‘pggga). Short-tailed Weasel (Mugtela gicggnanii). Long-tailed Weasel (Mustelg irgngta). Least Weasel (Mugtelg.;;gg§a). Domestic Cat Czalis domgsticg). milk snake (Lamprgpettig tgggggglgg), 'blue racer (Cglgbg; ggngtrictor), massasauga rattlesnake (Sistrurug getenetug). (Burt, 1948 and Manville. 1952). 73 As to nesting areas and space, and roosting space: Crow (Corvug hrgghyrhzgchog), Blue Jay (anocitta cri§t_a_t_g). Gray Squirrel (Sciurug .garglinensig). Fox Squirrel (SciurugIQngg). Man.(flgpg gapieng). Possible predation upon eggs and young: Raccoon Proc on.;gtgg). Gray Squirrel (Sgiurus garglingngig), Fox Squirrel (Sciuruglpiggg). As to interference in hunting areas: spring peeper (gylg grucifer). On April 14 in Area B. the author noted a great upwelling of the spring peeper's song from a swale lying northeast of the nest about 300 yards. The author noted that when he stood in a field directly north, adjacent to the nesting area. the spring peeper's song prevented his hearing of any other sounds. Thus, assuming the same auditory interfer- ence with owls. one of the most accessible hunting areas of the Iong~eared Owl might have been huntable only by sight. It is possible that this ex- plains in part the action of the female Long-eared Owl which appeared to hunt only in the deciduous woods west of the nest when observed late in the incubation period. Schwartzkopff (1952) noted that owls depend on their ears to an exceptional degree and even show specializations within the ear. Vgrtgbrateg Hgg-ggmpetitive withngpgregr§QIleg Vertebrates recovered from the pellets and nests of the Long-cared Owl: Blue Jay (Qzapgcitta cristatg), Crow (Cgrvug brachyghypchgs . Star- ling (Sturnug vulgarig), English Sparrow (Passe; domesticug). Eastern Meadowlark (Sturnella mggpa), Redrwing Blackbird (Agelaggs phgeniggug), 71+ grackle, Cowbird (Mglgthrus M). Cardinal (.fiighmgndepa cagdinalis), Pine Siskin (m Mi)- Slate-colored Junco (lung hyemalig), Tree Sparrow (Spigella grbgrea), Field Sparrow (Spigella pugilla), Fox Sparrow (Pagggrella M). SWamp Sparrow (Mglggpiza georgigna). Song Sparrow (Mglggniza mglodig). pheasant or chicken, Song. Vesper. or White-throated Sparrow, unidentified birds, Meadow Vole (Microtug w). Bog Lemming (W ggg'oeri), Meadow Jumping Mouse (Zappa W). Prairie Deer or, and White-footed Mouse (Pergmygcug sp.). House House (Egg pgsculug), Norway Rat (Rattug ngrvegicug , Short-tailed Shrew (_.'E_la_1;i_._n_a, brgvicaugg), Masked Shrew (Sgre; cincreug), Least Shrew (Cm. totig m). 75 FOOD HABITS - FIELD OBSERVATIONS Hunting Activity The time and frequency of hunting of the Long—eared Owls varied by the season. being different during spring and during the nesting period than during other seasons. However. certain non-nesting owls. perhaps young of the previous year. seemed to depart from this seasonal pattern. Non-nesting Individuals Non-nesting Longbeared Owls were observed in Area A.at the same time a pair was nesting there. Perhaps the three or four individuals seen.were yearlings from the same nesting pair. for Bent (1938) says the Long-eared Owl family keeps more or less together during the summer and fall and per- haps the winter too. On one occasion, four observers took up observation positions 100 to 200 yards out from each corner of Area A. Three or fOur owls were Observed six times in a period of 25 minutes, flying silently. about ten feet from the ground. A single owl landed on a brush pile and then darted to the ground. On another occasion. the author observed two Long-eared Owls when their evening hunt began in early April of 1954 in the Lansing winter roosting area. They flew about 50 yards after leaving their roosts and landed in separate trees about six feet above the ground. and appeared to look around. 76 Thus, hunting took place both from perches near the ground and by flying near the ground. All hunting activity observed always began west of the roosting area. During the Breeding Cycle During Pre-incubation Certain observations were made in Area B before incubation. On one occasion, the female left the nest at dusk and hunted for about ten min- utes in a deciduous woods lying several hundred yards west of the nest. Trapping in this area revealed a small population of mice in brush piles. At another time. the male Long-cared Owl was observed after dusk in thick stands of spruces lying east of Area B. Thus, the owls in Area B did not appear to hunt in the open fields but were seen in the spruce stand and deciduous woods. It is possible that at this time hunting could not have taken place in the fields because of the great upwelling of the spring peeper's song from a nearby marsh. The adjacent fields may have been impossible to hunt, except by sight alone. In contrast. movements of the mice were easily audible in the spruce grove. Southern (1955) reported that most owls locate their prey by hearing it. gazing Incubation On sash of the five evenings when observations were made during this period. the female Long-eared Owl left the nest quite regularly at 8:15 or 8:20 P.M. and was gone about ten minutes. On April 29. I observed the 77 female scrutinizing the surrounding area from her perch in the deciduous woods. but may beetles (Phyllophnge sp.) were the only prey for the owl that the author could observe. In England. Southern (1955) found that the main items of diet of the Tawny Owl (§§;gg.alugg) were mice and voles. yet from late spring through early autumn, these birds fed exten- sively of cockchafers. ground beetles, earthworms. young moles and rabbits. according to Southern because ground.vegetation was thick during this per- iod and mice and voles were not easily found. During the Kestling flags The male appeared to obtain all the food in the early stages of the nestling period. The female Long-eared Owl was never observed off the nest at this time in seven visits to the nest. Daytime hunting by the male when.the young were several hours to one day old was evidenced by the presence of diurnal prey. A decapitated Meadow Vble (Microtus pennfiylvanicug) was found on the morning of the day eggs hatched and on that afternoon. at 4:30 P.M.. there was a freshly killed Meadow Jumping Mouse (m hudsgniug), both within the nest. Lincoln (1920) noted that Iong-eared Owls occasionally hunt in the daytime and Whitman (192b) stated they hunt during the daytime when it is necessary to supply demands of the famihy. On May 19, when the young were four and five days Old, two decapitated Meadow Voles which were in the nest in the morning, were gone at 3:30 P.M. A single decapitated Meadow Vole was found in the nest at 3:00 P.M. the day the young were between six and seven days Old. Crow feathers were 78 Figure 25. Two nestling Long-cared Owls and two Meadow Voles in the nest in Area B. _ 79 found in the mouth of a nine day old owl in Area A. The young long-cared Owls in Area B were observed being fed by an adult when the young were 18 to 19 days old. The young called at broken intervals for nearly two hours before they were fed and the adult gave a soft rising call gpngh - gppgh - __Q_u:gh while feeding them. Thus. the male apparently obtained the food for the family during the early nestling stage. Later caring for the young was a joint respon- sibility of both adults. Although a jumping mouse in the nest during the early nestling stage indicated diurnal hunting by the male, this species of mouse did not appear in the owl pellets examined. Wilson (1938) found a relatively small percentage Of jumping mice in Long-eared Owl pellets he examined. During flip Fledgling Stage All observations upon fledglings were made in Area B. A 27 day old owl was observed being fed at 1:00 A.M.. June 10. The adult Called softly before flying into the place where the young was perched, and soft chipping notes of the young could be heard while it was being fed. The notes of the young owl were single, short. high-pitched or flute-like squeaks. The young owl was perched on the tip of a pine bough 15 to 20 feet above the ground. The adult flew to the young owl. hovered, and apparently placed bits of food in the fledgling's mouth. since no whole mouse was seen. The feeding operation did not take more than one minute. The night was cloudy and windy, with rain. illustrating the extreme con- ditions under which the adult Long-cared Owl could hunt. Southern (1955) 80 found that the Tawny Owl L§L§i§.§lpgg) in England could see mice when there was less than one millionth of a candle power or the amount of light falling on the forest floor on a cloudy summer night. The feeding active ities of the adults appeared to decrease during the latter part of this stage. to judge from the lesser frequency with which adult activity was observed. When the young was 28 days old, the adults fed it at 1:00 A.M. and again at 1:30 A.M. Eurigg 3211i m-flgdg ling m The young owl was heard calling at approximately 8:30 P.M. on June 17 (3% days old) while it was making flights of approximately 100 yards. Feeding of the young owl by the adults took place shortly after each of these movements. The apparent release of innate adult feeding behavior was observed on June 18. The author. attempting to obtain photographs of an adult Long-cared Owl. had caged a captive 67-day old owl and set up two cameras two to three feet away from the cage. The young owl had been starved for one day, and it was calling more often than usual. At 1:00 A.M., within a few minutes. an adult Long-cared Owl made two apparent attempts to reach the young owl. striking the cage with its wings both times. There are two important facts here. first. that the young owl was not the offspring of this particular adult. and second. that conditions were far from natural in the area. It would seem here that the feeding behavior pattern of the 81 adult Long-eared Owl occurred in spite of fear for itself. The last adult feeding of the young observed at night during this study took place at 3:15 A.M. when the young Long-eared Owl was 36 days old. An unusual call, a loud.ghu£;£ - gha - gha -‘gh§ -‘gh§, with a hoarse quality, was given by the adult before it fed the young. The last feeding cry of the young Long-eared Owl was heard by the author when the young owl was 50 days old. Bent (1938) reported that young Long-cared Owls were fed by the adults until the young were eight or nine weeks old; at this time, they had gained full power of flight and could hunt for themselves. The author observed a young owl flying quite well when only 33 days old; thus, this young was capable of full flight before it was seen to hunt for itself. Southern (1955) found young of the Tawny Owl in England to be dependent upon the parents until age three months. The same author found indirect evidence suggesting that newly independent chicks suffered a very high.mortality and evidence indicated this was due to an inability of the young to obtain food. Young Long-eared Owls might not suffer this particular mortality loss because the family remains to- gether through the fall. This gregarious nature of the family of the Long—eared Owls was discussed by Bent (1938). 82 FOOD HABITS - PELLET ANALYSIS During the breeding cycle. only pellets of young Long-eared Owls were examined while during the post-breeding cycle, only pellets of adults were examined. Winter accumulations of pellets from the post-breeding cycle were found in five different winter roosting areas. Pellets Producgd by _’_I_o_upg 91513 Neither of the two young Long-cared Owls in Area B were observed to eject pellets until it was 16 or 17 days old. In contrast, the author observed a captive owl a little over eight days old, which formed pellets within 2h hours after being fed animal remains. It is possible that the nestlings were not fed either the proper quantity or quality of food by the adult owls. It is not known why the adult owls continued to feed the young in this manner when the young are apparently capable of receiving a different diet. Pirnie (19h3) did not find any pellets under the nest of a Long-eared Owl before the oldest nestling was 16 days old. He credited the delay to the fact that early feedings consisted of small and readily digestible bits of meat while later feedings included larger pieces with more fur and bone. A number of pellets from young owls of known age were collected: the average measurements are as follows: 10 days, 2 pellets: avg. length - 38.5 mm avg. diameter - 14.0 mm 12 days, 3 pellets: avg. length - #1.? mm avg. diameter - 16.0 mm 83 13 days, 1 pellet: length - 47.0 mm diameter - 16.0 mm 1h - 15 days, 2 pellets: avg. length - Q3.0 mm avg. diameter - 15.0 mm 16 - 17 days, b pellets: avg. length - #9.8 mm 6 pellets: avg. diameter — 16.3 mm 18 - 20 days, 5 pellets: avg. length - 38.9 mm avg. diameter - 13.8 mm 25 days, 2 pellets: avg. length - #2.0 mm avg. diameter — 16.7 mm 26 days, 1 pellet: length - 29.0 mm diameter - 13.5 mm 30 days, 1 pellet: length ~ 26.0 mm diameter - 13.0 mm 39 days, 2 pellets: avg. length - 36.5 mm avg. diameter - 13.0 mm Thus, there appears to be no trend of increasing size in pellets produced by owls aged 10 to 39 days. Comparison with pellets produced by adult owls, however, suggests that those of the juvenile birds are slightly smaller. antgntg if; m Owl Pelletg The autor erected a funnel-like wire receptacle immediately beneath the nest in Area B to collect pellets of the young owls. The six pellets collected (May 31 to June 3) contained: four meadow voles (Micrgtug penngylvanicug), five whitefooted or prairie deer mice (Peromygcus sp.), one short-tailed shrew (Blarina.p§evicauda), and five unidentified mice (decapitated). .§l£s.2£néénli.2fll.Eallsis Measurements of length, diameter and weight were made of 72 whole Long-eared Owl pellets taken from accumulations found during 1953 and 1954 in the Lansing winter roosting area. Average measurements and ranges were: Number Measured Average Maximum Minimum Length in mm 72 46 92 20 Diameter in mm 72 19 29 10 Weight in grams 68 3.20 7.48 0.38 Two pellets weighing 4.4 and 5.1 grams on the day of regurgitation lost upon drying for two weeks, 2.3 and 2.7 grans respectively. The smallest pellet (which contained only one humerus) was 20 mm long, and weighed .4 grams. The largest pellet had a length of 70 mm, and weighed 7.5 grams. The next largest pellet had a length (maximum of all pellets) of 92 mm, and weighed 6.2 grams. The smallest pellet contain— ing two animals (one Micrgtug pgnnszlvgnicus and one,§g;g; ginereug; with only one major bone missing) was 23 mm long, and weighed 1.9 grams. The pellet containing the maximum number of animals (two Migrgtug penngylvanicug and three Pgromyscus sp.) had a length of 70 mm. Wilson (1938) reported the range in sizes of pellets of the Long-eared Owl to be: in length 2.7 to 8.4 cm.; in diameter 1.3 to 2.2 cm.; with average measurements of app- roximately 5 to 6 cm in length and 1.5 cm in diameter. 85 Number pi £11.12 911 Pelletg The exact number of pellets examined could not be determined because many pellets either broke up upon falling, or disintegrated from weather- ing. An accurate count of prey in 72 whole pellets was made. and from this an approximation of the total number of pellets was derived. The approximation was made according to the following formula used.by Wallace (1948): _:Q. whole pellet§:(72) - No. of broken pellets (X) No. animals in whole pellets (113) No. of animals in broken pellets (3263) X . 2079 pellets examined The average number of prey per pellet was 1.57. Wilson (1938) found an average of 1.7 prey items per pellet. The average number of prey per pellet does not equal the average number of prey consumed per day as shown by daily observations made upon a group of Long-eared Owls in the Lansing winter roosting area. The owls were counted each day, and all pellets were collected and examined, with the following results: No. of Prey §h&g_ E0. of Ovlg Kc. 9f Pgllgtg Animals April 3 l 2 2 April 5 3* 4 7 April 6 3 6 6 April 7 3 4 4 April 8 3"I 6 plus 8 April 9 2 2 plus 5 86 No. of Prey .Qgpg ETCL of Owlg No. of Pellet: Animalg April 10 3 3 5 April 11 _2 _2_ ___2_ Total During 8 Days 20 29 n 39 = 1.4 pellets per 1.3 animals owl per day per pellet I"These numbers are uncertain. This rough approximation revealed that the Long-eared Owl sometimes may eject more than one pellet per day. Identification 9:,gdglEIQE; Pelletg The average Long-eared Owl pellet is long and cylindrical and.measured approximately 4.6 cm. in length and 1.9 cm. in diameter. variation existed as I have already shown. The only pellets included in this study were those thought to be surely from Long-eared Owls. Pellets were used from roosting areas where Long-eared Owls were positively identified, or from large accumulations of pellets in known Long-eared Owl habitat. Large accumulations of pellets were important in identifying roosts of the Long-eared Owl because of the gregarious nature of the species. There was relatively little variation in diameter among pellets ob- served by the author; similarly Wilson (1938) found that Long-eared Owl pellets seldom varied more than a few millimeters in diameter. While a few Long-eared Owl pellets may resemble those of the Screech Owl, the diameters of the long-eared Owl pellets were always much greater than 87 those of Screech Owl pellets. Long-eared Owl pellets are too small in diameter to be confused with pellets of the larger Barred Owl (Strix varia) or Great-horned Owl (Bubo virginianus). Pellets of the Short-eared Owl (Asio flamneus) are more similar to pellets of the Long—eared Owl, and since the Short-eared Owl is also gregarious (Bent 1938), some confusion might occur where the ranges of the two species overlap. Here positive identification of the owls should be made before deciding the identity of the pellets. Contents. 912$;ng 9i M93113; The prey animals found in the Iong-eared Owl pellets from the five roosting areas are listed on Table 1. Nice, making up 95.7 to 97.0 percent of all prey numbers, were used most heavily. Within the mouse population, the Meadow vole (Microtg§_pennsylvanicug) was most important, and comprised 73.3 to 91.1 per cent of the total. Pellets from the roost in Area A, the roost adjacent to Area B and the roost in.Jackson County showed 73.3, 76.1 and 75.6 per cent Meadow Voles, respectively. The relay tive abundance of these animals in the owl pellets may be an indication of their relative abundance in the three areas. Pellets collected from the white pine winter roost and the Lansing winter roost contained higher proportions, 85.3 and 91.1 per cent Meadow Voles, respectively. Prairie Deer and White-footed Mice were found in the Long-eared Owl pellets in sufficient numbers to appear to be a steady source of food in most areas. The winter mouse prey was supplemented by two other species, the Bog Lemming BEE... H 8 8 mass mmuoHam gauze Ha maeeaem on any uozouasmae one use: aamaHzo has woomeHaa_»waem. ewamaza magma A333. 5:33. A333. 5.33. awn—eon 9533. 59 «5333. Ha Ha bade. h 98 woman one a»: «powwow Humans been been Hog.“— «0 P39 m 3.05 aoEpwH 0953‘ b w hues. w mamas amass: 20. \aa Ho. m 2.0. m H4o. & mo. m H40. mm Hac. u HAAo. R .mmmmpmma massaawmmmmmmn mum Aam.ov emu Aso.mv HHN Asm.mv Hum Aou.sv Houm Ase.HV mm Aeo.ov am Amo.mv woos Aso.av weedmaHo.mwmmpmmn mm A m.uv no A a.mv Hm AHo.HV m: AHH.oV Hus AH~.oV Hm A o.sv mom A o.:g E3 «o .banIo “3 uA .3 NA .5 o A F3 HA .8 HoA .E .wnmemammmm me. Hum ANH.mV Hoo AHo.:v Ha AHH.:V w: AHm.oV am A “.mv ms AHV.:V mm Amu.mv pm: AHu.ov Eh E H A .5 H A .8 E900 Mm “Huh" Hm n pug ER. 253 um: MESS» whammHoHHm NA .8 ‘ NA .5 meuaum_esm4someam u A .:V H» A ~.uv : A N.sv : A N.ov H: A H.HV o A a.mv m A H.sv rm A H.mw Figs Peerage H A .Hv N A .5 H A .3 m A .5 c A .u mmnwsnapn.wmmnm H» A H.mv H» A .:V .mpmmu oe.mmnmwpwwn H A .HV H A .Nv H A .sv u A .HV 36% Human: mwkwwnmggm aw. m A 9.8 m A .5 E Haas? H A .3 H A .8 mean aHeam Hm A H.mv mxA,H;mu away rev H A .Mv ma A n.0v mm A~:.mv as a N.~v eosmH meow mHm AHoo.v “Hm AHoo.v Hem AHoo.V moH AHoo.V HuHm AHoo.V Hum AHoo.V HHo AHoo.v ammo AHoo.v 89 (§ynantomys coooeri) in three areas, and the House Mouse (gas musculus) in one. The remaining prey of the Long-cared Owl made up less than five per cent of the owl's total diet and included the Norway Rat (Rattug norvegicus) and various species of shrews and birds. Pellet Analyses by Other Workers Pellet analyses of Long-eared Owls by other workers in Michigan (Table 2) give further information. The following studies have been made of winter pellet deposits: A.S. Warthin, Jr. and J. Van Tyne (1922), who examined 110 pellets collected near Ann Arbor, Michigan on.January 21, 1922; Charles J. Spiker (1933) who collected and examined 200 pellets on February 19, 1933; near Saline, Michigan: Aelred D. Geis (1952) who ex- amined a number of pellets recovered during the winter of 1951-52 at the Kellogg Bird Sanctuary, Michigan: and.Kenneth A. Wilson (1938) who re- covered pellets from September, 1932 to May, 1933, at a site in the vio- inity of Ann Arbor, Michigan. Wilson observed a small representation of _§apg§ hudsgniug implying that his pellet analysis probably was not in total a winter one. Wilson's study also adds a bat to the list of Long- eared Owl prey, (Mygtis lucifpgus). Geis's study revealed that onry one bird species. the Pine Grosbeak (Pipigglaigpgglggpgg) was preyed upon by the Long-eared Owl. All four studies show that W m- sylvanicug was preyed upon far more than any other animal and that mice comprised practically all of the prey. awMHm N wmmw mwMOHMm wodfib Hm wmbbmam 0% 6mm Bo mlm>wuv oAb wM oamww HMaowm Hz ZHomHmwz smeewa mum