A SURVEY OF ROBIN (TURDUS MiGRATORiUS} WPULATiONS EN RELATED?! TO DUTCH ELM DISEASE CONTROL N10 GTfiER ENSECTECEDE USES Thesis for? film but» «if M. '5. hfiCHIGAN STATE UNWERSFFY Garafid C. Kai-tum K361- LIBRARY Michigan State University , ‘- 3H - ..'.\J‘ A SURVEY OF ROBIN (IQRDQS MIGRATORIQ§) POPULATIONS IN RELATION TO DUTCH ELM DISEASE CONTROL AND OTHER INSECTICIDE USES By GERALD C. KETTUNEN AN ABSTRACT Submitted to the College of Science and Arts Michigan State University of Agriculture and Applied Science in partial fulfillment of the requirements for the degree of MASTER OF SCIENCE Department of Zoology 1961 Approved 3 144$“, z blagflag‘ Gerald Charles Kettunen During the springs of 1959 and 1960 a survey of Robin (Iggggg miggatorigs) populations in relation to Dutch elm disease control and other insecticide uses was made on the Nbrth Campus of Michigan State University as an attempt to assess the effect of these Operations on campus bird life. Spraying of elms for Dutch elm disease began in 1954. The program was expanded in 1955, and the treatment became full scale in subsequent years. Both dormant and foliar sprays were used until 1959, when the foliar sprayings were discontinued. In a previous three-year spring and summer study (1954- 1957), it was shown that there was a decline of the nesting Robins on a 5-acre study plot from 5 successful pairs in 1954 to l unsuccessful pairsin 1957. The entire North Campus (184- acres) population was not known but only 15 adults and 1 young were found there during late June censuses in 1957. Robins were first noted dying on the campus in 1955. Reasons for the decline were believed to be related to earth- worm poisoning. Tissue analyses of Bbbins and earthworms in Illinois showed that both had concdntrated DDT. ’ In censuses taken in 1959, the Robin population fluctu- ated from a.maximum count of 22 on April 14 to a minimum of 4 on the 22nd of May and 5th of June. April counts were fairly constant with an average of 17.3 adults observed in 8 counts. This was thought to have been due to prompt replacement of Robins which had succumbed to insecticide poisoning. Unmated males and females were ap- parently quick to find new mates. Many observations were Gerald Charles Kettunen made of Robins dying during the spring of 1959; few if any young were fledged from campus nests. By the end of June, 50 records of dead and dying Robins had been collected on an area where the original spring papulation was about 10 pairs. Robins were nearly a month late in arriving in numbers on the study area during the spring of 1960. Abnormal spring weather in the southern wintering areas was thought to have delayed the movement of migrants. weekly counts of Robins during April, May, and June of 1960 gave a maximum of 36 Robins on April 18. On April 30, 15 living Robins were counted, by which time 16 dead birds had been turned in or reported. The May counts showed a steady decline from the 15 noted on April 30 to 3 on May 22. June counts fluctuated from 3 to 4, but the birds observed were apparently non-nesting strays, appearing in new places. Nesting during the spring of 1960 was unsuccessful. 0f the 12 nests located, 10 terminated in the early stages; 2 others were doubtful. Dead Robins were found in the vicinity of nearly all the nests. Eggs were found to contain DDT in all stages from the development of the egg follicles in the ovaries to the newly hatched young. Fall counts in 1959 were concentrated mainly on bark- foragers, in hopes that an appraisal could be made of the ef- fects of dormant fall sprays on these species. Counts of chickadees fluctuated greatly, varying from a low of 7 to a high of 56 without any discernable pattern of Gerald Charles Kettunen increase or decline. In a January census only 4 chickadees were recorded and none were found in February. It was assumed that the concen- tration of chickadees observed during the fall gradually dis- persed rather than suffering any heavy mortality from the small amount of spraying that was done during the fall of that year. Only 4 were reported dead or dying during this period. Transient Red-breasted Nuthatches and an occasional White-breasted Nuthatch were also recorded during the fall censusing, but were not observed during the January and Febru- ary counts. Few dead or dying birds were reported during the fall or winter (1959-1960), but during the spring of 1960, 95 dead birds of 15 species were found on the campus. In the 12 censuses taken on a 66 acre plot in residential East Lansing in the spring of 1960, only 3 Robins were recorded. The counts of other species were also low. Late June surveys on the North Campus and in residential East Lansing during the summer of 1960 indicated an extremely low late June population of Robins over much of the city. From an analysis of Audubon Field Notes it was not_ possible to single out any one factor responsible for declines or increases in Robin pOpulations over the United States as a whole. The weather, food supply, and man-made causes all play a part in causing these fluctuations. A SURVEY OF ROBIN (TURDUS MIGRATORIUS) POPULATIONS IN RELATION TO DUTCH ELM DISEASE CONTROL AND OTHER INSECTICIDE USES By GERALD C. KETTUNEN A THESIS Submitted to the College of Science and Arts Michigan State University of Agriculture and Applied Science in partial fulfillment of the requirements for the degree of MASTER OF SCIENCE Department of Zoology 1961 LIST OF FIGURES . INTRODUCTION . . . METHODS OF STUDY . ACKNOWLEDGEMENTS . DESCRIPTION OF THE Location . Vegetation Uses of the SPRING CENSUS DATA 1959 SPRING CENSUS DATA 1960 NESTING DATA 1960 DISCUSSION . . . . TABLE OF CONTENTS STUDY AREA Area Spraying History 0 i (to. e 33' (be e 0 Local Robin Populations Fall and Winter Censuses Survey of Audubon Field Notes SW 0 O O O 0 LITERATURE CITED . 11 O Page iii ‘ WWNNU‘IUIU‘I-P'Ul . U700.) 10 _. -b g HCDU'1 10 CD U1 .5 Figure U'I-F‘Uh) LIST OF FIGURES 184-acre North Campus Study Area . . Robin Censuses During the Spring of 1959 Robin Censuses During the Spring of 1960 Nesting Data Spring 1960. Robin Distribution Correlated with Speirs' Isothermic Boundaries -Christmas Census 1955- 0 O 0 Robin Distribution Correlated with Speirs' Isothermic Boundaries ~Christmas Census 1957- . 0 Robin Distribution Correlated with Speirs' Isothermic Boundaries -Christmas Census 1958- Robin Distribution Correlated With Speirs' Isothenmic Boundaries ~Christmas Census 1959- 111 Page 11 17 21 42 43 44 45 INTRODUCTION This study is an investigation of the Robin (gugggg migratozius) pOpulation on the Michigan State University Campus, and an analysis of the records published in Audubon Field Notes (1956-1960) of the Robin populations wintering in the central and southern states. The Robin study was chosen for three reasons: (1) the writer's interest in the problem of DDT spraying and its possible connection with an observed die-off of Robins on the Michigan State University Campus; (2) the need for further research on the problem; and (3) the hope that the results obtained in the study might aid in solving the problems cre- ated by insecticide use and its effects on bird papulationi The field work and survey of published records upon which this thesis is based was carried on during the spring, fall, and winter of 1959 and the spring of 1960. An examination of published records in Audubon Field Netes was made with the hope of establishing some definite trends which would give a more accurate picture of the winter- ing Robin populations in the central and southern states. Spring, summer, and fall data were included where it was thought that these were significant. Speirs (1954:176) found that the area of greatest winter concentration of Robins lies between the latitudes of 30° and 55° N., with extensions northward into eastern North Carolina and central Tennessee and southward into the peninsula of Florida and into the wooded regions of south- eastern Texas. Mehner (1958) writes; ”Speirs' conclusions were veri- fied by 30 foreign recoveries of Robins banded at East Lansing from 1925 through 1942. With one exception all were between November and March. Of the 29 recoveries during the late fall and winter, 20 (60 per cent) were between the latitudes of 30° and 35° N." Speirs (1953, op. cit.) also found the majority of the winter recoveries of banded Robins have been made in the region lying between the average positions of 40° F. and the 60° F. January isotherms. Actually only about 6 per cent of the winter recoveries occurred in regions north or south of these isotherms. The 40° F. isotherm for January corresponds well with the northern boundary of the region in which less than 15 days per winter have continuously freezing temper- atures. In this region it is to be expected that Robins would usually be able to find unfrozen ground and a supply of food. The region in which the Robins are most abundant in winter corresponds very closely with the oak-pine and the pine associes of the deciduous forest biome. The lack of re- coveries from the mesquite areas of southern Texas and southern Florida suggests that forested areas as well as favorable temperatures are winter habitat requirements. U METHODS 2_ STUDY The North Campus at Michigan State university was selected as the main study area. Data were secured in the spring of 1959 by making observations on foot. A.tota1 of 19 trips, involving 112 hours, was made from April 7 to June 9 (1959). This time was spent in counting and recording mated pairs, single individuals, and the young which fledged. The territories, those areas where Robins were quite regularly seen, were designated by the buildings or areas around which they were observed feeding, singing, and nesting. Observations were made both with and without binoculars. A survey of Audubon Field Notes (the bird records pub- lished six times annually by the National Audubon Society in collaboration with the U. 8. Fish and Wildlife Service) was made during the winter of 1959. Records of the Christmas Bird Counts (published in Audubon Field Notes) from 1956-1960 were studied and the data mapped to permit comparison from year to year and to note fluctuations in the wintering papu- lations. The weekly counts during the spring of 1960 were taken by a team of two, three, four, or five observers. The writer was a member of the observing teams, which worked over assigned routes covering the North Campus study area. Observations were made during a two-hour period (6 A.M. to 8 AeM.) when there was little commotion from moving vehicles and pedestrians. CKNOWLE MENT It is with sincere thanks that I acknowledge the interest, help, and advice of all those who aided me in this study. In particular I wish to thank Dr. George J. wallace for his willingness to discuss any aspect of this study, for his ad- vice, and for his constructive criticism during the preparation of this manuscript. I am also indebted to the other members of my committee, Dr. James C. Braddock and Dr. Roland L. Fischer, for their help in reading and criticizing this thesis. I am grateful to the U. S. Bureau of Sport Fimheries and wildlire for the grant which financed a part or this study. I also wish to thank Richard Bernard, Ernst Lucas, Willet T. Van Velzen, and Ralph Moldenhauer for their help in obtaining census data during the spring of 1960. DESCRIPTION QE THE STUDY AREA Location The study area is located on the Michigan State Univer- sity Campus at East Lansing, in the southwest quarter of section 18 and the southeast quarter of section 19, Meridian Township, Ingham County, Michigan. It covers approximately 184-acres (0.303 square miles), and is bounded by a highway (U.S. 16) on the north, the Red Cedar River on the south and a residential area (Bogue Street) on the east. The western end terminates in a point by the near mergence of the river with the highway. (Figure 1.) Vegetation The campus at Michigan State University is an arboretum of great variety and beauty. A total of 3,622 different woody plants (including the accessions of 1960) can be found on the campus; however, not all of these are located on the North Campus study area (Baron,1960). The study area has both deciduous and coniferous plants, but the deciduous varieties are more numerous. American elm (M13 W) constitutes 59.6 per cent of the trees. Red maple (492; m), soft maple (Age; sacchagigum), and Norway maple (Age: plagtoideg) together.make up 23.8 per cent. Black oak (Quercus velutina), red oak (Quezcus 22233), and white oak (QEQ:£2§,§;2§) comprise the remaining 16.6 per cent. Figure 1. 184-acre North Campus Study Area a 7 The percentages are based on the total number of elms, oaks, and maples of 6 inch d.b.h. (diameter at breast height) on the study area. Uses of the Area The area contains dormitories, classroom buildings, office buildings, library, machine shops, power station, and two botanical gardens. The landscaped areas around the build- ings and the botanical gardens serve as nesting places and feeding grounds for the Robins and other birds. None of the area is under cultivation for the purposes of raising crops or domesticated animals, but the gardens are subject to more or less continuous experiment and transplantation. Frequent construction of new buildings and heavy pedestrian and auto- mobile traffic may well have considerable effect on bird life, but how much is unknown. Spraying History of the Area The spraying history of the area was obtained by Dr. wallace through interviews with Professor Lautner, Head of Urban Planning and Landscape Architecture, and members of his staff. The results described here are taken from a progress report on the grant (No. 14-16-008-575) between Michigan State University and the U. 3. Bureau or Sports Fisheries and Wildlife. Campus elms were first sprayed for Dutch elm disease in 1954 with the experimental treatment of a few trees. The program was expanded in 1955 and in subsequent years'becauea a full scale treatment of all elms. Both foliar and dormant sprays were used until 1959 when the foliar sprays were dis- continued. Approximately 2300 elms on 880 acres come under the care of the "Grounds Department"; about 565 of these are on the 184-acre North Campus study area. Along the highway (U.S. 16) bordering the campus is a long double row of large elms, which are sprayed regularly, but these come under the Jurisdiction of the State Highway Department. Rotomist sprayers are used to spray campus trees and the dosages are said to conform to the recommendations out- lined in the MSU leaflet (Strong, et a1, 1955) on Dutch elm disease control. This specifies a 12-1/2 per cent solution of DDT (one part of a 25 per cent DDT emulsion to one part of water) for dormant sprays and a 6-1/4 per cent mixture (one part of a 25 per cent DDT emulsion to three parts of water) for foliar sprays. gram CENSUS DATA 1252 In southern Michigan the first spring migrants are often noted in early March. Wallace (1945: 117) writes; ”in 1945 the first Robin was recorded at East Lansing on March 5." In 1946 there was a flood of migrants during the first days of March (Wallace, 1946:163). Hewever, in 1947 there were only scattered individuals present during that part of the month; otherwise, the Robin was not found until March 19-20 or later (Black and Wallace, 1947:171). Sometimes early migrants may arrive in late February; Mehner (1958) observed a male and female in a residential area of Lansing on February 25, 1957. The March 31 Robin arrival date for 1958 was the latest Dn.Wallace has recorded in East Lansing (Wallace, pers. comm.). In 1959, Robins wintered in the Lansing area. Five were seen flying across the campus on February 23. Hewever, they were not reported again in East Lansing until March 24 (Wallace, pers. comm.). ‘ On April 7, I made my first census of Robins on the 184-acre study area and continued these counts twice weekly through the months of April and May, terminating on June 9. The Robin papulation fluctuated during this time from a maxi- mum count of 22, on April 14, to a minimum of 4 on the 22nd of May and the 5th of June. The population was quite constant 10 through the month of April with an average of 17.3 adults be- ing observed. The consistency of the counts during April may have been due to the prompt replacement of dying Robins by new birds, as new females were quick to respond to the songs of unmated males, and vacated territories were promptly reoccupied. How- ever, during the month of May and early June the population dwindled steadily with replacements coming more slowly. Our counts ranged from a maximum of 15, on one census in early May, to a minimum of 4 in early June. The decline in numbers is also evident in the graph (Figure 2) of the weekly counts. It is likely that some of the low counts of living Robins in May and early June are incomplete as the densely foliaged trees may have concealed some of the non-singing birds. By the end of June there were still several pairs of Robins observed making an attempt to nest and raise young. However, by this time 50 records of dead and dying Robins had been collected on an area where the original spring population was about 10 pairs, which was also close to the maximum number present in my April 14 count. It can be seen from the preceding data that the total loss of Robins in a given area may be several times greater than the entire population present at any one time. The virtually Robinless campus at the end of the 1958 nesting season (Wallace, 0p. cit.) posed the interesting question of what the situation would be in 1959 on the North Campus study area. With the influx of Robins during April of Figure 2. Robin Censuses during the Spring of 1959 all? IJT 11 Hutch wk.» swunwuux xi... .3 M. u 4 on «N 3.. \N it r x. vzser V/v/A mks—39¢ E n j? sex leN\ |$\ nix I .\ AIIIL .. on iflN wane... 12 1959, it was possible to observe them setting up territories and trying to nest and raise young. However, the elimination of some of the breeding stock by apparent insecticide poison- ing (birds analyzed by Bernard, pers. comm.) severely reduced nesting success. Records from my field notes show: April 21: ........I observed a male Robin with symptoms of DDT poisoning near the Uhion Building. As,I approached, it tried to fly, but could not get Off the ground. A lack of equilibrium was noticeable; the bird tended to teeter forward as it stood in one place. The eyes were closing and Opening with seemingly little coordi- nation. ........ April 30: ........I observed another male Robin in the vicinity Of NOrth Williams dorm, with symptoms of DDT poisoning. Even though there was evidence of a loss of equilibrium, the bird could still fly. Flight was labored and so I tried to overtake the individual, but this proved futile. The Robin flew across the river, and up into the lower branches of some nearby trees. Approximately four days later I went to the vicinity where I had last seen the Robin and found a dead bird. I presumed it was the same one I had Observed. It had apparently been dead for several days as it was quite "ripe." ........ May 1; ........I observed a tremoring male Robin near the Union Building. It fluttered its wings and flicked its tail up and down con- stantly; its tarsi were flat against the ground and the bird appeared to have no control over its leg movements. Before death ensued, violent spasms, with the bill Open much Of the time, occurred. The bird fell on its back in an attempt to get 13 away from me. It flapped its wings, as a gradual tightening and tenseness of the body and wings was observed. The primary feathers were spread out, and then a final spasm throughout the body Occurred. May 13: ........I discovered a nest near the Practice Music Building. The female was on, and was seen again On the nest on May 15, 18, and 22. On the 28th I saw both the male and female, but the nest was not attended by either one. I checked the nest site again on the 29th, but did not see the male or female. Checks of the nest were made on the 3rd and 5th Of June, but neither adult was observed. I presumed that the eggs had been laid several days previous to my discovering the nest and that the pair had given up trying to incu- bate them. Possibly the birds were killed by a predator or died from insecticide poisoning, as the nest was deserted. It should be mentioned that I did not get to see the eggs as the nest was out of reach. Predators might have destroyed the eggs, as there were Blue Jays (Cyanocitta cri tata) and Common Grackles ( uiscalus guiscula as well as.Fbx squirrels Sciurus niger) in the vicinity of the nest when Obser- vations were made. However, I did not find any telltale shells on the ground below the nest. ........ May 28; ........I observed a male, female, and One young (capable of flight) feeding in the North Williams dorm area. As I approached they flew over the river onto the baseball field. I did not see them in that area again. ........ May 29; ........Observations were made of a female and one young near the Band Shell. The young bird was able to fly. I saw them again on June 4th, but did not see them during the counts made on the 5th and 9th. ........ 14 Thus, while the recorded spring die-off of Robins during 1959 was relatively low in actual numbers, the significant feature was that it represented several times the maximum spring population. "Obviously the campus is serving as a grave- yard for most Of the Robins that attempt to take up residence in the spring," (Wallace, op. cit.). . SPRING CENSUS DATA 1260 wallace (1960, pers. comm.) states; "Robins were not numerous on the study area until mid-April (nearly a month behind schedule) during the spring of 1960." This may have been due to weather conditions in the southern regions where an abnormal spring may have retarded migration. Bagg (1960: 386-390) reported that, "migrations Of far below normal numbers of Robins were experienced in the Western Great Lakes Region, Appalachian Region, and the Middlewestern Prairie Region." Spring was also late in the East Lansing area. Spray- ing of campus elms was retarded by inclement weather and it was not until April 13 that about 40 elms were treated. Spraying was continued intermittently through April and was completed sometime in early May. Counts of Robins (and other birds were taken weekly on the study area by a team of two, three, four, or five ob- servers working over assigned routes. The writer was a member of these teams. Some duplication may have resulted from this census method, as when a Robin flies into or crosses more than one observer's route, but this was probably more than Offset by birds that were missed, particularly in late May and June, when dense foliage may have concealed non-singing birds. Even though the counts were made during the early morning, the 15 16 reliability of singing male counts was not valid in all cases, as the widely spaced territories reduced competitive singing. Often only one or two Robins were heard singing during the count periods. Many non-singing birds, however, including males, could be found through thorough searching. A graphic presentation of the 1960 spring census data, showing the trend or decline from April through June, can be found in figure 3. The first census of the study area was made on April 2. It was a cloudy overcast day with the temperature ranging between 41-420 F. A count of 5 (plus 2 flying overhead) was recorded. Eight days later, on April 10, the count of Robins was still 5 for the 184-acre study area. On April 18, follow- ing the first warm rains, a maximum count of 36 Robins was made. The first tremoring Robin was found later that day. On April 23, our count was down to 25, and on the 30th it was down to 15. Wallace (1960) stated that, "up to this date (April 30), 16 dead Robins had been turned in or reported (13 actual specimens turned in, 3 others not saved)." A further decline was evident in May, reaching a minimum Of 3 on May 22. The counts in June ranged between 3 and 4, but it was Obvious that these were not the ones present in May, since the May birds had been found dead in their territories. The June Robins were apparently new birds, non-nesters, appearing in new places. Wallace (1960) states; "toward the end of June there was a slight increase in Robins (up to 9 or more on June Figure 3. Robin Censuses during the Spring of 1960 mznh xaz imam .. O\ the“ x3...» 5!. c R~K\L\ hkwafl$x the... kg?» to hkuewfi‘ ,rllli. .. $\ ihx 18 26, the last count) including several fully-winged young of the year, apparently not produced on the study area." Recoveries of dead Robins were lower than in the spring of 1959, when at least 50 dead or dying individuals were so- cured from an area where the maximum count in 30 censuses was 22. The specimens received in the spring Of 1960 totaled 22 plus 9 others not saved or not turned in (found chopped up by mowers, too "ripe? to save, or reported but not turned in). This did not include 18 Robins seen "with symptoms," but not captured; it can be assumed that some of these were recovered later as dead birds. According to Wallace (Op. cit.) there were two reasons assigned for the lower recovery of specimens during the spring of 1960; ”(1) Robins were unusually scarce in peripheral areas surrounding the campus, thus limiting continuous re- cruitment; and (2) some key people (bird students, nature study classes, campus pick-up men) who were asked to turn in or report dead birds did not always do so." NESTING DATA 1260 During the spring of 1960 12 nests were found on the study area and these were checked regularly On the weekly surveys, or more often in some cases. Ten of the nests terminated unsuccessfully, during nest building or incubation, apparently due to the death of the adults (dead Robins were found in the vicinity of nearly all the nests). Wallace 19 (op. cit.) states: ”one nest disappeared after it had been located.” Each of 2 nests contained 2 nestlings for a time, but these disappeared, probably before leaving the nest, although it is conceivable that they fledged. Careful search in the vicinity of the nests at about nest-leaving time dis- closed neither adults nor young. Unhatched eggs examined by Bernard (pers. comm.) were found to contain DDT, but the effects of DDT on hatchability of Robin eggs, or the deveIOpment of the young, are not known at this time. A more illustrative concept of the nesting success during the spring is found in figure 4. 20 Campus Nest Locations -Spring 1960- Negt Number IOOOOOOOOOOOOOOOOOOOOO 2 OOOOOOOOOOOOOOOOOOOOC 3 eeeeeeeeeoeooeeeeeeee AOOOOOOOOOOOOOOOOOOOO. 5 eeeeeoeeoeeeeoeeoeeeo 6 OOOOOOOOOOOOOOOOOOOOO 7 .OOOOOOOOOOOOOOOOOOOC 8 OOOOOOOOOOOOQOOOOOOOO 9 OOOOOOOOOOOOOOOOOOOOO ‘0 OOOOOOOOOOOOOOOOOOOOO 11.00.000.0000000000000 12 OOOOOOOOOOOOOOOOOOOOO Location in elm near fire hydrant at the SW corner of Mason-Abbot Dormitory. . in pine east Of Music Building. in spruce over boulder in center of campus. in pine west of Williams Dormitory. in spruces west of Music Building. in elm in front of Conservation Building. in elm by Band Shell. in elm in front of Giltner Hall. in spruce along the river behind the Art Building. in cedar by stadium entrance (across river on South Campus, but Robins fed in part on North Campus). in Jackpine beside Women's Gym, on Beal Garden side. in evergreen at entrance to Snyder Dormitory (nest disappeared- Donna Coller). Date April 18 April 25 April 30 May 2 May 8 May 9 May 11 May 12 21 Figure 4 Nesting Dflta Spring 1950 Nest Number 2 3 4 5 6* 7 8 9 10 11 x + + + x - + .+ x + x' + . x' x x x x .- x' - x x - x x x x - .- x' r x - x' X. I. I - - x x' a x' - - - - - x' .- - .- - - - Key: female on or building nest female in the vicinity Of the nest nest attended by both male and female (building nest or in vicinity of neat) nest unattended nest incomplete and deserted DISCUSSION Previous studies related to this investigation were made by Mehner (1958) and Barker (1958). During 1954, 1956, and 1957, John F. Mehner (1958) made spring and summer pOpulation studies of the Robin on the Michigan State University campus, and on another study area adjacent to the campus. His campus area was the Horticultural Gardens, which was a more or less rectangular shaped plot approximately 5.5 acres in extent; however, this was previous to the construction of the Student Services building and adjacent parking lot. In 1954, five pairs of Robins nested successfully on the 5.5 acres, an average of one pair per acre. Only two nests were found in the Gardens in 1956, of which one was successful. Mehner states that, "in 1957, two nests were located in the Gardens, but neither produced any young." During the three summer months of 1954, young Robins and adults fluctuated in numbers, with an average of 4 young to 4.5 adults in the seven counts made. In 1956, an average Of 2 young to 2.8 adults was tallied in five counts. In 1957, however, the average of young to adults was 0 to 2.8 for five counts. My spring studies included the Horticultural Gardens; 22 23 however, Robins did not nest there during my period of study, nor were they seen feeding in the area regularly. Wallace (1959 a) states that, "detailed studies were not made in 1958, but three censuses taken in June, July, and August yielded only 3 Robins in the July cOunt, none in the June and August counts. At no time during the summer were fledglings Observed on the main campus by Dr. wallace or re- ported by other people. In the spring of 1955, a year after the first spraying of campus elms for Dutch elm disease began various Observers reported dying Robins. The Robins exhibited symptoms of partial paralysis and loss of balance, followed by tremors, convulsions, and death. This was also very apparent to me as ‘I picked up many paralyzed specimens which could not fly. None of the specimens collected survived; they showed the general pattern of loss of balance, followed by tremors, con- vulsions, and death. It was suspected that insecticidal poisoning might be the cause and that earthworms might be the toxic agent in- volved. In a research project in which campus earthworms were fed to crayfish, the crayfish all succumbed (Porter, pers. comm.). Campus earthworms fed to a caged snake apparently produced similar symptoms (Hensley, pers. comm.). However, the full details of how this cycle Operates in Robins was largely speculative until Roy J. Barker (1958) investigated the problem at the University of Illinois. ’ 24 Barker's investigations showed that earthworms accumu- late and concentrate DDT in their bodies by feeding on contami- nated leaf mulch. The earthworms analyzed had deposits of DDT throughout the digestive tract, with large deposits in the crOp and gizzard (403 ng/g.). Lower levels were found in the body wall, the dorsal blood vessel, and the ventral nerve cord. Barker's analyses of the dead Robins on the Illinois campus revealed that the digestive tracts of the dead birds were empty. This suggested that the Robins had acquired DDT in a material which was quickly digested, such as earthworms. It is common knowledge that during the spring Robins feed largely on earthworms and that the first brood of young in the spring is reared largely on earthworms. Thus, when a Robin is eating DDT-infested earthworms as its main source of food during the spring it in turn accumu- lates DDT in its body. Eventually the DDT reaches the brain cells, apparently causing locomotor paralysis and convulsions, followed by death. In my investigations an analysis of the viscera was not carried out; however, the evidence of having found and ob- served Robins suffering from a paralysis, led me to hypothe- size that the Robins on the Michigan State University campus were dying of paralytic DDT poisoning. A study of the tissues of the Robins collected by this writer and others was carried on by Richard Bernard (pers. comm.) and it was found that DDT in varying amounts was concentrated in the brain, liver, 25 heart, and breast muscle. Local Robin POpulations Population studies other than those on the Michigan State University North Campus were also made in East Lansing by Tom Jegla, Ernest Lucas, and the writer. During the summer of 1959 Tom Jegla, a graduate student, made a study of the Marble district in East Lansing, part of which had been sprayed for the control of Dutch elm disease. The following data were taken from his unpublished report. Jegla's study plot covered 48.6 acres and has mostly privately owned, unsprayed elms (816), but there are a few right-Ofeway (21), school ground (28) or privately sprayed (9) elms, too. The area was a potentially good site for Ebbins and other ground feeders. Spraying of the city-owned elms in this area was carried out on August 5-13, 1958, and this was followed by a dormant spray in April of 1959. Residents were encouraged to have their trees sprayed, but apparently few did so, due to cost. Hence, it appeared that more than one-half of the elms were not sprayed. However, the district shared in the community aerial spraying program for mosquitoes and other insect pests in 1958 and 1959. No dead or dying birds were found during the summer study, but several had been reported earlier in the spring. The average number of Robins per observation was 15.3 On 48.6 acres. The number Of Robins per acre was 0.32 or 32 26 per 100 acres. The ratio of males to females was 95 males to 52 females. There was no explanation for this discrepancy other than that the area may have been serving as a feeding site, rather than for nesting. However, the presence of adult birds day after day in about the same places suggested that some of them were on territories. Nesting studies were not made here due to the late start of the project. The ratio of adults to young was 153 to 15 (10.2:1). Apparently few young were fledged, and of course those observed may have come in from other areas. In conjunction with my Campus studies I made several surveys of an area approximately one-eighth of a mile south and east of the Marble district. The area covered contained about 66 acres and had about 500 small or medium-sized elms closely linhg the unpaved streets. It is bounded on the north by Mount Vernon Avenue and on the south by Melrose Avenue. Hagadorn Road forms the westerly boundary, while the eastern boundary is formed by a woodlot and marsh. The elm trees were reported by Mr. Emerson, Parks Superintendent Of East Lansing, to have had their first spray- ing (foliar) on August 5-13, 1958, followed by a dormant treatment in April of 1959 (Wallace, 1960). Twelve censuses were made here, starting on April 22 and continuing through the month of May and up to June 3. My first record of Robins in the area was on May 9, when 3 were seen. They were not observed there on the follow- ing day. The remaining 6 censuses revealed no Robins; so I 2? assumed that the three birds seen (May 9) may have been visitors from a nearby woodlot or were migrants. One pair Of Blue Jays was seen on April 26, presumably out of the nearby woodlot. I did not see them again during the subsequent counts. The tally of other species was: 5 Starlings, 1 Common Crackle, 1 Cardinal, and 1 Red-winged Blackbird (Agelaius phoegigeus). These surveys indicate that the Robin population as well as those of other species was extremely low in the area. Wallace (1960) states that, "during the last week in June, 1960, Ernst Lucas, a graduate student, searched the North Campus for young Robins and made surveys of residential East Lansing for adults and young.” One young Robin, pre- sumably not produced on the campus, was seen on June 23 and another (or the same one) on June 25. Two adults were seen and another heard on June 24, and a tremoring Robin was found, but not captured on June 28. Lucas' East Lansing surveys were somewhat superficial, mainly an attempt to appraise the late June production of young. He toured all of the north and south streets of a sizable portion of East Lansing (the area circumscribed by Grand River Avenue, Abbott Road, Burcham Drive and Gunson Street) and scanned lawns and premises for Robins. Obviously some Robins would be missed by this method, but it was an index to the potential late June population. In four cruises over the 246-acre area (about 62 city blocks) Lucas recorded no young Robins, but heard one Robin on June 26, heard two on 28 June 27, heard one and saw one on June 28 and heard one on June 29. Since some of the Robins recorded on successive days were in the same territory, the indicated total for the four surveys was less than six individuals. Fall and Winter Censuses In conjunction with the Robin study Fall censuses were made in hOpe that an appraisal could be made of the effects of dormant fall sprays on bark-foragers (RObins and most foliage gleaners were gone by the time the fall censuses started). A local influx of Black-capped Chickadees (Earns atricapillus) and some White-breasted Nuthatches (Sittg| gagolinensig) as well as a few Red-breasted Nuthatches (Silt; canaggnsis) provided a good Opportunity for pOpulation studies. Several "miscalculations" however, disrupted the study: (1) leaf fall was late in 1959 due to a mild October, so that spraying was not begun as anticipated; (2) the rapid onset of cold weather in early NOvember postponed spraying operations more or less indefinitely; and (3) when 40 elms were finally treated in the northeast corner of the campus, we were not notified of the operations and thus no follow-up studies on the birds in the immediate vicinity Of the sprayed trees were made. Wallace (1960) states that, "three chickadees with symptoms and one tremoring nuthatch were reported on or near 29 the sprayed area, and in the spring the dried up carcass of another chickadee was found under the snow. An 'affected' chickadee appeared to have typical poisoning symptoms and when analyzed was found to contain 122 ppm of DDT in the heart, 56 ppm in the breast muscle and 68 ppm in the liver." The counts of living chickadees on my study area fluctu- ated greatly during the fall months, varying from a low of 7 to a high of 56 (on October 21) without any discernible pattern of increase or decline. The counts were fairly con- sistent between 20 and 40 up to December 13, when my fall studies terminated. On January 9, a team of five census takers explored the 184-acre study area quite thoroughly and recorded only four chickadees; on February 20, six observers found none. It was assumed that the concentration of chickadees observed during the fall gradually dispersed rather than suffering any heavy mortality from the small amount of spraying that was done locally (on campus or in East Lansing) in the fall of 1959. (Some chickadees remained overwinter in nearby woodlots and visited some local feeding stations, but they were not seen again on the North Campus.) Wallace (pers. comm.) states that “transient Red-breasted Nuthatches and an occasional White-breasted Nuthatch were also recorded on the campus census area in the fall, but were not observed during the January and February counts. One Hairy WOodpecker (pegdrocogos villosus) was recorded 5 times in 25 counts (October 21 to November 21) and a Downy WOodpecker 30 (DegdrocOpos pubescens) was seen 3 times in November; both may have been visitors from a nearby woodlot (Sanford) or adjacent parts of East Lansing. No dead woodpeckers (except a reported/abut an unretrieved Yellowbshafted Flicker (Colaptes auratus) were reported from the study area, but the Hairy and Downy WOodpecker have been scarce in recent years; the Downy in particular was formerly a common patron of feed- ing stations in residential East Lansing." NO significant pOpulation trends or mortality figures were evident in the fall and winter counts of House Sparrows (Passe; domegtiggg), Starlings (Sturnus vulgaris), Blue Jays (Cyanocitta gristata), or Cardinals (Richmondena cardinalis). Wallace (op. cit.) also states that, "during the spring of 1960, most summer resident insectivorous species (except swifts) were absent or occurred only as stragglers, whereas Rock Doves (Columba liyia), House Sparrows, Common Grackles, and at times non-nesting Starlings and Brown-headed Cowbirds (Molothggs 232;) were abundant. MOurning Doves (Zenaiduga gacroura)--an average of 22.3 on 13 countse-appear to be hold- ing up fairly well. Blue Jays seemed conspicuous at times, although the counts yielded an average Of only 6.4 (3-11) on 13 counts. , At least 95 dead birds Of 15 species were reliably re- ported from the campus during the spring. In addition to Robins (31), some 20 HOuse Sparrows, 15 Mallards (Ana; platyrhynchos), 6 Common Grackles, 5 Starlings, 5 Cardinals, 4 Chimney Swifts (Chaetura pelagica), 2 Blue Jays, and one 33 each of 7 other species were reported. Presumably many others were not reported. Except for the Chimney Swifts, which were presumed to have died from starvation during a prolonged rainy spell, and a transient Ovenbird (Seiurus aurocapillus), samples analyzed by Bernard (pers. comm.) usually yielded fairly high concentrations of DDT." Survey of Audubon Field Notes A winter study Of published records in Audubon Field Notes was made with the hOpe that one could establish some definite trends, which would show a decline, increase, or a static condition, thus giving a more accurate picture of the wintering Robin populations in the central and southern states. Spring, summer, and fall data were included where it was thought that these would be of significance. From the analyses Of the field notes and plotting and mapping the Christmas Count data from 1956 through 1960 (figures 5, 6, 7, and 8) the following is presented to help clarify the roles that weather, food supply and man-made causes played in the distribution and numbers during the four-year period. Robbins (1956) states that, "the winter of 1956 was one Of extremes in temperature and in precipitation. There was little consistency from month to month or from area to area. The net result was a confusing pattern of record-breaking meteorological statistics, each Region reporting its own peculiar conditions." All but two of the regional editors 32 commented on the wintering pOpulation of Robins. In the Southern Atlantic Region the species was scarce (figure 5). In all other regions exceptional numbers were noted in all or at least some of the reporting areas. Throughout the whole Northeast "phenomenal" numbers occurred, accounting perhaps for the scarcity in the Carolinas. The unusual distribution of this species cannot be correlated with concurrent weather conditions. Maurice Brooks (1957) correlated Robin abundances with the heavy crOp of wild berries in the Appalachian Region. Morgan dnd Emery (1956) reported that, "in the Northeast Mari- time Region Robins wintered in great numbers until late March when they became hard pressed, stripping bare everything edible." Robbins (Op. cit.) states that, "in the Hudson-Saint Lawrence Region where the winter was about normal until March's heavy snowfalls, Robins wintered in phenomenal numbers. The birds occupied a relatively narrow north-south area with the heaviest concentrations in northern New Jersey. Flocks ranged from as far north as Quebec City, to SouthamptOn, Massachusetts, where the largest flock of 126 birds on February 12 was reported.” Many reports indicated that the birds were feeding on rotting drops in apple orchards. In contrast, the Southern Atlantic Coast Region reported scarcities of Robins as well as of other birds. Wild food crOps appeared to be generally short. It was judged by observers that in some areas bird pOpulations were down one-half to two-thirds of what they were four years ago. 33 Pettingill (1957) states that, "from the Atlantic Coast through the Rocky Mountains during the winter season of 1957 the mildness Of the weather did not bring about any outstand- ing reports on avian pOpulations. The winter season was ”quite uneventful“ ornithOIOgically and this was true for the country as a whole. Only two regions reported Robins present in large numbers. These were (1) the Northeastern Maritime Region, where Robins were present in numbers from Massachusetts southward--1000+ being recorded on the Newport Count; and (2) the Appalachian Region, where the birds were being found wherever there were crOps of beechnuts and wild grapes." Hence, except for the Northeastern Maritime and Appalachian Regions records indicated fewer Robins in 1957. During the fall of 1957 Newman (1958) states that, "an abundance of Robins were reported in the northern states. ‘ However, the bulk Of the birds soon departed and by the end of the period great numbers had already reached coastal Georgia and the lower Rio Grande Valley." Belated winter weather in the East and Middle West pro- duced some belated southward movements and mortality during the winter of 1957-1958. Mortality due directly to exposure, or indirectly to the adverse effects of the weather on the availability of food was encountered frequently during the late winter, particularly in the hard hit Southwest. There were abundant records of starved or "frozen" birds thrOughout the East. The Robin was victimized the most, being reported killed from Ohio to southern Florida, the numbers totaling 34 into the hundreds in South Carolina. The area reporting the greatest general mortality was, surprisingly, southern Florida where Tree Swallows (Iridoprocge bicolor), Purple Martins (Progng gubig), Catbirds (Dumetella carolinensis), Robins, and Myrtle Warblers (Qendrgica corgnata) perished in signifi- cant numbers. 1 Even though some areas were reporting staggering losses the over all picture of the Robin situation was considered excellent. The Appalachian Region reported that Robins were widely distributed, particularly where there were crops of wild grapes and flowering dogwood fruits. From the Middle- western Prairie Region, James (op. cit.) states that, "large flocks of Robins began to appear in Kentucky, Indiana, and Ohio in mid-December and continued to arrive until late January. The Utica, Ohio Christmas Count recorded over 6000 Robins sharing a Starling-Blackbird roost; at Bloomington, Indiana, over 2000 were found, most of them in two congre- gations; there were 5000 at Madisonville, Kentucky, on December 29, although they did not become common at Toledo until Janu- ary 20 or so (when there were numerous flocks of 200). Robins were very abundant in the HOuston Area, where it was estimated that over 100,000 roosted in the woods on the Rice Institute Campus." Thus the records show large concentrations, but heavy winter mortality in 1958. The arrival of birds on their breeding grounds was from a week to two weeks later than normal during the Spring Migration of 1958. Nichols (1958) states that, "the number 35 of migrants was generally reported as relatively low and some expected species were locally absent. It was thought that the sustained weather in the southern United States caused a high mortality among the wintering birds. The second factor contri- buting to the irregular and rather meager flight of the land birds, particularly of the insectivores, was attributed to the heavy spraying during the spring and summer of 1957 with insecticides or pesticides in many localities in the southern part of the St. Lawrence Region. From Long Island it was re- pOrted that on days following spraying, numbers of dead and dying birds were found. These were usually warblers, tanagers, thrushes and swallows which had succumbed either to direct spraying or starvation." MOrgan and Emery (1958) stated that, "one cannot but wonder whether or not this was the beginning Of records reporting a drastic long-term reduction in the birdlife as a result of massive spraying programs. The out- standing examples include the RObin, Eastern Phoebe (Sgyornis phoebe), Empidonax flycatchers, Tree Swallows, House wren (Trgglodytes agggn), Eastern Bluebird (Sialia sialis), both species of cuckoos, and the Rusty Blackbird (Euphagus carolinus). Migration throughout the HUdson-St. Lawrence Region was uniform, but poor and late. The factors that contributed to this were probably many and diverse, but those that were placed at the top of the list were: (1) unfavorable weather during the late winter and spring, (2) the results of heavy spraying with DDT and other pesticides during the preceding spring and summer. To this may be added the insect 36 control measures in the wintering quarters of the insecti- vorous migrating birds." Bull (1958) states that, "the Nesting Season of 1958 was one of delayed breeding and the production of small numbers of young. A cold rainy spring which was prevalent over much Of the eastern 2/3 of the area was reflected in the late arrival and delayed nesting Of a number of species of passerine birds. Another factor, regarded as detrimental to birds and other organisms, was the spraying Of lethal insecticides. Fer ex- ample, the Gypsy Moth in the North and the Fire Ant in the South, were the targets of federal, state, and local groups that hOped to eradicate noxious pests.” Nicholas (1958) states that, "the direct effect of the poisonous sprays on nestling birds must also have its place. The trapping of birds in the eastern portion Of Long Island revealed that about 50 percent of the birds that were trapped during the summer of 1958 had been banded in previous years and represent an older segment of the birds; the low frequency of young birds was pronounced." Breckenridge (1958) reports that, "nesting Robins in the Western Great Lakes Region were reported as extremely scarce throughout the Detroit area. There has been a decrease over the last three years, but it was much more evident this summer. It is known that many Robins, Starlings and others have died from spraying for Dutch elm disease in Detroit and its suburbs." 37 The Fall migration reports indicated reductions of the pOpulation very much in evidence. One significant observation by Street (1959) was made after a spraying for control of the Gypsy Moth at Pocono Lake, Pennsylvania. The spraying took place in June and shortly after the bird pOpulation decreased by 75 per cent. Robin numbers were down in the winter of 1959. In the Appalachian Region Christmas Counts, Robins were as much as 90 per cent lower than a year ago. Robins decreased at least 50 per cent in 9 out of 13 counts in the Florida Region and declined from 9,701 individuals last year (1958) to 450 in seven counts in Kentucky. James (1959) states that, ”in evaluating the RObin pOpulation of 1959 it is important to recognize that last winter the species was superabundant throughout its range. From the Middlewestern Prairie Region Robins were below normal regionwide. Exceptions were at Columbus and Cincinnati, Ohio. At the latter place, 15,000 to 20,000 frequented one roost, while in another up to 5,000 were estimated to have been present." The Spring Migration Of 1959 was one in which only scattered reports were received about the Robin flights. Some of the areas reported increases; the Appalachian Region reported most of the species that last year (1958) had suf- fered greatly reduced populations had made rather good cond- backs during 1959. Hall (1959) states that, "this was parti- cularly true of the Robin, Eastern Phoebe and'Esstern Bluebird, but the warblers had not recovered." 38 Mumford (1959) reports that, "on March 18, 19, and 20 at Blue Island, Illinois, Japanese Beetle control, by the spraying of heptachlor from aircraft, was conducted over a 25 square mile area. Many Robins (as well as House Sparrows, Starlings, Common Grackles, 1 Browneheaded Cowbird, and 1 Brown Thrasher) were found dead between March 22 and May 14. During this period, 184 dead birds (of which 22 were banded) were recovered. Some of these were Robins found dead within 40 hours after banding (and thought to be new arrivals). The normal nesting pOpulation of 500 to 600 Robins was estimated to be down to 20 birds. Common Grackles were down 75 percent. Nine dead birds examined contained varying amounts of hepta- chlor." Numford (1959 b) states that, "nesting during the summer of 1959 produced very few young for the populations which were in need of replenishment. The Middlewestern Prairie Region reported die-offs of Robins at Blue Island, Illinois, follow- ing the March spraying of heptachlor which evidently involved breeding birds, as none were known to nest in the entire city and it was July 30 before any were observed. Robins seemed on a decline at Moline and East Moline, Illinois, because of heavy spraying to combat Dutch elm disease." The reports from the Fall Migration Of 1959 were all in agreement about the abundance of Robins during the migration period. The Winter Season of 1960 started out as a uniform pattern of weather which began with the general mildness and 39 culminated in a severe late winter from mid-February to the last week in March. James (1960) states that, "during the early winter the Robin pOpulation seemed to be in an upsurge, but in March the cold spell dissipated the flocks. Last season (1959) only half of the reports from Florida listed the Robin and the state's total Of only 3,583 individuals tempted one to believe the species was being rapidly decimated by excessive use of poison sprays on the northern breeding grounds. This year (1960) 88,846 Robins were reported in Florida emphasizing the fact that one must be extremely careful not to jump to con- clusions based on local records in a single Christmas Count period.” Reports of dead birds found in emaciated condition came from all quarters of the Central Southern Region and covered a wide range of species including sparrows, blackbirds, warblers, thrushes, Robins, bluebirds, swallows, doves and woodcocks. Thus it can be said of the 1960 winter season that it was one in which fluctuations in the Robin population did not show any definite trends. Due to the variability in the re- ports submitted it is possible to reiterate what has been said before--one should not draw any definite conclusions re- garding pOpulation fluctuations from the limited reports Of just one season's records. A shift in wintering area may_be the reason for some areas having below normal, normal, or above normal wintering populations. 4O Bagg (1960) states that, "the 1960 Spring Migration was accompanied by a very abnormal spring in most of the areas re- porting. The number of Robins was again difficult to assess because of sharply diverse opinions." Bagg and Emery (1960) state that, "the 1960 Nesting Season was marked by a lack of young produced in some areas during the first nestings. However, second nestings produced young in some areas, but not in any great numbers." Nichols (1960) reports that, "Robins were generally numerous throughout the HUdson-St. Lawrence Region, but many reports were heard of dead or sick birds found on lawns in suburban areas; many of the birds showed signs of paralysis." In Michigan very few Robins were reported nesting, - especially in areas where spraying was done. This was very evident in my,Nesting Study on the North Campus as no young were known to have fledged. Banders reported that very few immature Robins were caught. Lupient (1960) states that, "in Wisconsin, Robins and Eastern Bluebirds had seriously declined in numbers." Mumford (1960) states that, "the Middlewestern Prairie Region also reported Robin numbers lower, down 30 to 50 per~ cent at Utica, Ohio. Nesting Robins have increased only 5 percent at Blue Island, Illinois, where none were known to nest in 1959 following heptachlor spraying; an estimated 5 percent fledged young this season of 1960." Comparing Speirs' data with the Christmas Counts of 1955. 1955, 1958, and 1959, revealed some very interesting 41 correlations as well as discrepancies. In 1956 large concentrations of Robins were wintering well above the 40° F. isotherm (Figure 5). The 1957 Christmas Counts showed that the major portion of the population was well within Speirs' boundaries; however, fairly large concen- trations were also censused north Of the 40° F. January iso- therm (Figure 6). . During the winter of 1958 a large portion of the winter- ing population was again concentrated north of Speirs' range (Figure 7). Georgia, Florida, and Tennessee were the only states within Speirs' range which had large numbers of winter- ing Robins. South Carolina's lows were attributed to the extreme cold which plagued the southern portion of the Southern Atlantic Coast Region. The Christmas Counts of 1959 revealed that wintering Robins were well within Speirs' boundaries (Figure 8). A de- creased pOpulation could still be seen in SOuth Carolina; however, increases over the previous years counts were evident. One might attribute the lows recorded in Mississippi's wintering pOpulation to the fact that there may have been a shift of the pOpulation into the Southeastern Texas Region-- James (1958) states that, "an estimated ioo,ooo Robins roosted in the woods on the Rice Institute Campus." The year-to-year comparison of Christmas Counts failed to show any definite trends-~declines, increases, or a static condition. The fluctuations observed were the result of the combined effects of the weather, food supply and man-made causes. -Figure 7- Robin Distribution Correlated with Speirs' Isothermic Boundaries Christmas Census 1958 -Figure 8- Robin Distribution Correlated with Speirs' Isothermic Boundaries Christmas Census 1959 """"" I ( .1, fi“_-‘-l-—"Af *l/l 45 '-_--—- . ‘ e. . ' ‘ : ‘0 . e 1‘ f A 1.. ... a" , .. -. . i I L . e e . .0 \‘ .‘ ' x ' 0 emeueg .u. w '. . ‘ I. . . . ‘ ' . ‘ 09".... ' - \ . J. \ I eeeeeeeeeeeo ‘ - 1“ C o ’ . . l ‘ ‘ L - V ' -' -» . e coco-'00.." . / . ' ' . h 9‘ Ter’x . .'l I ’ - V ~ 00.00."..2“ (I , 1 a, ' - A ‘ ‘ . J .v ‘ o ‘ O .h.‘ i : . ' . : o o S o l o . a t . . r e. . ~ . . a . n ‘1 i‘ AA--.‘ . _,I:_ - -. - ’. "> D ’ ‘0 1 e .4 - I. 7“ ‘ . , . ’f‘ ' . a : - _ ,. - 0 o ‘ ‘ O I eh ” -' ° 4 x O ‘ ‘ . . . r 9.. _ ' r - . ‘ :‘4 e. 4 A 'i': la- }‘.9' .. v' - ~ . , _ , ‘4' '... . I , a. ~ , .v I. ‘ '2‘; :9 -< V 1 . l .7 c ., .Y 1 mg: 9 ‘_ 4 . ,l‘v ‘ .14 i594: ‘ _ ’ > v‘. Wt: ,..I~r _ I . :- "",\ _ - . . 1 , p ‘ -‘ {x it ...'_ ~ .‘I a '1’ we- 4 . . “zfi'ffiféfi‘if'a'w w y, *7 -' '7? ' - " Iff‘f‘f’ "I” ., . £1 l e .'t-,- v-rw; -~ pezggc‘wiwwi "V" " '-~ _ ,, ngwtffik'fi , . 7w ' ' _ 1""!‘7? 5.". ‘ ‘4 , ~._'( ...-'.I",;‘_. 1 a» . ~ . . l .e I . ‘. ,_ 3.54 ,. ._. \‘M J Orr/00 W A survey of Robin pOpulations in relation to Dutch elm disease control and other insecticide uses was madeuduring the springs of 1959 and 1960 on the 184-acre North Campus of Michigan State University at East Lansing. This_study area has a predominantly deciduous vegetative cover, with the American elm comprising 59.6 per cent of the trees. The re- maining 39.4 per cent is made up of 23.8 per cent maple and 16.6 per cent oak. Located on the study area are classroom buildings, dormitories, various administrative and utility buildings, and two botanical gardens. The area is not cultivated for raising crOps, nor is it used for rearing domesticated animals. Spraying of elms for Dutch elm disease began in 1954, when only a few treestwere treated. The prOgram was expanded in 1955, and the treatment became full scale in subsequent years. Both foliar and dormant sprays were used until 1959, when the foliar sprayings were discontinued. In a three-year spring and summer study (1954-1957) in the 5-acre Horticultural Gardens, Mehner showed a decline of the nesting Robins from 5 successful pairs (1 pr./acre) in 1954 to 2 unsuccessful pairs in 1957. . Detailed studies on the North Campus were not made in 46 4.7 1958, but Wallace's records showed no Robins on June 21, 3 in July, and none in August. RObins were first noted dying on the campus in 1955. The decline was believed to be due to earthworm poisoning, as earthworms constitute the Robins staple food in the spring. Tissue analyses of Robins in Illinois showed that they had concentrated DDT in their own systems, after having eaten earthworms. The earthworms analyzed also contained DDT. Censusing of the Robin populationnwas begun on April 7 in 1959. Thorough counts were made twice weekly through the months of April and May and were terminated on June 9. The Robin population fluctuated during this time from a maximum count of 22 on April 14 to a minimum Of 4 on the 22nd of May and the 5th of June. During April the counts were fairly constant with an average of 17.3 adults observed in 8 counts. This was thought to be due to prompt replacement of the Robins which died Of insecticide poisoning. Unmated males and females were apparently quick to find new mates. By the end of June, 50 records of dead and dying Robins had been collected on an area where the original spring pOpu- lation was about 10 pairs, which was also close to my maxi- mum count on April 14. Many observations of Robins dying of presumed insecticide poisoning were made during the spring of 1959; few if any, young were fledged from campus nests. 48 Robins were nearly a month late in arriving in numbers on the study area during the spring of 1960. Abnormal spring weather in the southern wintering areas may have delayed the movement Of migrants. Spraying Of campus elms was retarded due to the inclement weather during the spring, but was continued intermittently through April and was completed sometime in early May. Weekly counts were made of the Robins during April, May, and June of 1960, by teams of two, four, and five observers. On April 18, a.maximum count Of 36 Robins was made. On April 30, 15 living Robins were counted and 16 dead birds had been turned in or reported. In May the counts showed a steady decline from the 15 Robins noted on April 30 to 3 on May 22. June counts fluctuated from 3 to 4, but the birds ob- served were apparently non-nesting strays, appearing in new places. Nesting during the spring of 1960 proved very unsuccess- ful. Of the 12 nests located 10 terminated unsuccessfully in the early stages and two others were presumed to have failed to fledge young. Dead Robins were found in the vicinity Of nearly all the nests. Eggs, on examination by a chemist, were found to con- tain DDT in all stages from the develOpment of the egg follicles in the Ovaries to the newly hatched young. Counts on bark-foragers during the fall of 1959 were 49 made in hOpes Of determining the effects of dormant fall sprays on these species. Three chickadees with symptoms and one tremoring nut- hatch were reported, along with a dried up carcass of another chickadee found under the snow. Counts of living chickadees on the study area fluctu- ated greatly during the fall, varying from a low of 7 to a high of 56 without any discernible pattern of increase or de- Cline. On January 9 only 4 chickadees were found; on February 20 none were seen. It was assumed that the concentration of chickadees observed during the fall gradually dispersed rather than suffering any heavy mortality from the small amount of spraying that was done in the fall that year. Transient Red-breasted Nuthatches and an occasional White-breasted Nuthatch were also recorded on the campus census area in the fall, but were not observed during the January and February counts. During the spring of 1960, 95 dead birds of 15 species were found on the campus. In the Marble district of East Lansing during the summer of 1959, one observer reported an average of 15.3 Robins per Observation on 48.6 acres. The ratio of males to females was 95 to 52. Another pOpulation survey (by the author) was made on a 5O nearby area. In the 12 censuses taken only 3 Robins were Ob- served. Other species were scarce also: 2 Blue Jays, 5 Starlings, 1 Common Crackle, 1 Cardinal, and 1 Red-winged Blackbird were all that were recorded. Late June surveys on the North Campus and in residential East Lansing during the summer of 1960 indicated an extremely low late June pOpulation of Robins over much of East Lansing. From an analysis of Audubon Field NOtes it was not possible to single out any one factor responsible for declines or increases in Robin populations. The weather, food supply' and man-made causes all play a part in causing these fluctu- ations. Hewever, the birds seem to recover from decreases created by inclement weather and food shortages by producing larger clutches of young in the years after the decline. But increasing use of pesticides, ceilometers, higher T.V. towers, expanding housing develOpments, and other modern develOpments may bring about declines which may have more permanent effects on birds. A comparison of the Christmas Census data of 1956-1959 with Speirs' theory of Robins wintering between the 40° F. and the 600 F. January isotherms revealed large concentrations of Robins wintering well above the 40° F. isotherm. However, in 1957 and 1958 there were also concentrations of considerable size wintering within Speirs' hypothetical boundaries. Robins wintered well within the 40° F. and 60° F. iso- therms during 1959; however, flocks numbering from 500-1000 were also in evidence north of the 40° F. isotherm. LITE TURE gggpp Bagg, Aaron M. 1960. Spring Migration, April 1 - May 31, 1960 And. Field Notes, 14 (4) : 365-390. Bagg, Aaron M. and Ruth P. Emery 1960. Nesting Season, June 1 - August 15, 1960 And. Field Notes, 14 (5) : 434. Barker, Roy J. 1958. Notes on Some Ecological Effects of DDT Sprayed on Elms. Jour. Wildlife Mans ement, 22 (3) : Baron, Milton 1960. New Rare Plants on Campus, December 28, 1960 List No. 12. Leaflet, Dept. of Urban Planning and Landscape Architecture, Michigan State Univer- sity, East Lansing, Michigan. Black, C. T. and G. J. Wallace 1947. Seasonal Records of Michigan Birds - Spring, 1947. {aggrgigg,wa ble , 25:162-176. Breckenridge, W. J. 1958. Nesting Season, June 1 - August 15, 1958 And. Field Notes, 12 (5) : 412. Brooks, Maurice 1957. Winter Season and Winter Bird Population Study, December 1, 1956 - March 31, 1957 ,Agd. Field Notes, 11 (3) : 264-266. Bull, John L. 1958. cNesting Season, June 1 - August 15, 1958 And. Field Notes, 12 (5) : 392. Hall, George A. 1959. Spring Migration, April 1 - May 31, 1959 And. zield Not 3, 13 (4) : 369. Hunt, Barrie L. 1960. Songbird Breeding Populations in DDT - Sprayed Dutch Elm Disease Communities. Jour. Wildlife Mana ement, 24 (2) : 139-146. 51 . 52 James, Douglas 1958. Winter Season and Winter Bird-POpulatiOns Study, December 1, 1957 - March 31, 1958 {Aud. Field Notes, 12 (3) : 260-291. James, Douglas 1959. Winter Season and Winter Bird-Population Study, December 1, 1958 - March 31, 1959 App. Field Notes, 13 (3) : 2711. James, Douglas 1960. Winter Season and Winter Bird-Population Study, December 1, 1959 - March 31, 1960. And. Field Notes, 14 (3) : 295. Lupient, Mary 1960. Nesting Season, June 1 - Au ust 15, 1960 Aud. Field Notes, 14 (5) : 52. Mehner, John F. 1958. Studies on the Life History of the Robin (Turgug migratorious). Ph.D. thesis, Michigan State University, East Lansing, Michigan, unpublished. Morgan, Allen and Ruth P. Enery 1956. Winter Season and Winter Bird-POpulation Study, December 1, 1955 - March 31, 1956. Aud. Field Notes, 10 (3) : 235. Morgan, Allen and-Ruth P. Emery 1958. Spring Migration, April 1 - May 31, 1958 Aud. Field Notes, 12 (4) : 335. Mumford, Russell E. 1959a. Spring Migration, April 1 - May 31, 1959 Aud. Field Notes, 13 (4) : 373. Mumford, Russell E. 1959b. Nesting Season, June 1 - August 15, 1959 Aud. Field Notes, 13 (5) : 434. Mumford, Russell E. 1960. Nesting Season, June 1 - ust 15, 1960 Aud. Field Notes, 14 (5) z 53. Newman, Robert J.- 1957. Spring Migration, April 1 - May 31, 1957 And. Field N tes, 11 (4) : 355. Newman, Robert J. 1958. Fall Migration, August 16 - November 30, 1957 Aud. Field N tes, 12 (1) : 9. 53 Nichols, Charles K. , 1958a. Spring Migration, April 1 - May 31, 1958 Aud. Field Notes, 12 (4) : 336. . Nichols, Charles K. 1958b. Nesting Season, June 1 - August 15, 1958 Aud. Field Notes, 12 (5) : 397. Nichols, Charles K. 1960. Nesting Season, June 1 - August 15, 1960. Aud. Field Noteg,14 (5) : 438. Pettingill, Olin Sewall, Jr. 1957. Winter Season and Winter Bird-POpulation Study, December 1, 1956 - March 31, 1957 Aug. Field Notes, 11 (3) : 244. Robbins, Chandler S. 1956. Winter Season and Winter Bird-Population Study, December 1, 1955 - March 31, 1956 Aud. Field Notes, 10 (3) : 232. Speirs, Murray J.- 1953. Winter Distribution Studies Of Robins East of the Rocky Mountains. Wilson Bull., 65 : 175. Street, P. B. 1959. Fall Migration, August 16 - November 30, 1958 And. Field Notes, 13 (1) : 17. Strong, F. C., Janes, R. L., and Morofsky, W. F. 1955. Dutch Elm Disease Control _ Extension Folder F-195. May 16, 1955. Michigan State University COOperative Extension Service, Michigan State University, East Lansing, Michigan. Wallace, G. J. 1945. Sezsonal Records of Michigan Birds - Spring, 19 5 Jack-Pine Warbler, 23 : 106-122. Wallace G. J. 1946. Saigonal Records of Michigan Birds - Spring, 19 Jack-Pine Warbler, 24 : 154-167. Wallace, G. J. 19593. Insecticides and Birds. Audubon MES: 61 (1) : 10. . . Wallace, G. J. 1959b. PrOgress Report to Fish and Wildlife Service, NOvember 13, 1959. Unpublished. 54 Wallace, G. J. 1960. Final Report on M.S.U. - Fish and Wildlife Service contract. Unpublished.