$33 FACTQRS AFFETENG wammcx SMZNG POE—”Uififllfiié Ei‘éDEIfiES EN SCE‘L‘E'ZfiRN MmHifiAN Thesis far: 5:335: Sages (23' M S. i‘s‘iCHEGAE‘é Si’éfi'é QNTJERSITY IHIHllllfllllll“IllllllU“IIIlHll”lUlLlHLllllalHH||lfl 3 1293 104883 I. I B R A R Y Michigan Stan University FACTORS AFFECTING WOODCOCK SPRING POPULATION INDEXES IN SOUTHERN MICHIGAN BY William Hardy Goudy AN ABSTRACT Submitted to the School of Graduate Studies of Michigan State University of Agriculture and Applied Science in partial fulfillment of the requirements fof’themdegreeeofrf MASTER OF SC IENCE Department of Fisheries and Wildlife Year 1960 ABSTRACT American woodcock (Philohela minor) spring population-level es- timates commonly are determined from roadside counts of males on their singing grounds. This study was undertaken to attempt improvement in the accuracy of these counts. In 1954, 1955, and 1956, an average of thirty counts were con- ducted each spring on one or the other of two southern'flichigan singing-ground routes. Statistically significant differences were found among many of these counts. The causes of this variation were ascertained by determining (l) the effect of various biological and climatological conditions on woodcock.courtship activity, and (2) the factors affecting observers' abilities to hear the singing-ground performance. As results, the fbllowing recommendations were suggested as a basis for standardization in woodcock singing-ground counts in southern Michigan: 1. Counts should be made during the period April 20 - May 10. 2. Counts should be limited to the 30 minutes immediately following the first singing-ground flight. 3. Roadside air temperatures should be above 40° F. at the time of the first singing-ground flight. 4. Wind velocities should be less than 15 miles per hour. 5. When the interference index isyb (on a scale provided for this purpose) for a single stop or above 2.25 average per stop for the total route, the data for that stop or route should be eliminated from analysis. 11 FACTORS AFFECTING WOODCOCK SPRING POPULATION INDEXES IN SOUTHERN MICHIGAN BY William Hardy Goudy A THESIS Submitted to the School of Graduate Studies of Michigan State University of Agriculture and Applied Science in partial fulfillment of the requirements for the degree of MASTER OF SCIENCE Department of Fisheries and Wildlife 1960 ACKNOWLEDGEMENTS This study was made possible through the cooperation of the Depart- ment of Fisheries and Wildlife at Michigan State University and the Michigan Department of Conservation. It was designated as part of the Game Division's Pittman-Robertson Research Project 90-R. Credit for conceiving the study is due Dr. A. B. Geis, U. S. Fish and Wildlife Service, Laurel, mryland, while he was a graduate fellow at Michigan State University. Appreciation is expressed to Dr. L. H. Blankenship, Division of Game and Fish, Minnesota Department of Conserva- tion, for guiding and assisting with the field investigations while serving as project leader for Michigan's woodcock investigations. Dr. D. W. Rayne, now of the U. 8. Fish and Wildlife Service, Laurel, Maryland, suggested and supervised the statistical work while he was Professor of Zoology at Michigan State University. Much gratitude is expressed to Dr. G. A. Petrides who, on return to Michigan State University from overseas leave, gave advice on the study, edited the manuscript and was instrumental in the conpletion of the dissertation. Thanks also go to Dr. P. I. 'l‘ack, Head of the Department of Fisheries and Wildlife, and Dr. G. J. Wallace, Zoology Department, Michigan State University, for their critical reading of the dissertation. Dr. D. W. Douglass and‘Mr. R. A. MacMullan served as administrators of the study for the Game Division and Dr. C. '1'. Black made the facilities at the Rose Lake Wild- life Rxperiment Station available for the field work. iv TABLE OF CONTENTS Page ABSTRACT . . . . . . . . . . . . . . . . . . . . . . . . . . ii 'l‘I'l‘LEPAGE ACKNOWLEDGEMENTS . . . . . . . . . . . . . . . . . . . . . . iv INTRODUCTION........................ 1 s'nmrnus 3 FLUCTUATIONS IN SINGING-GROUND COUNTS . . . . . . . . . . . 5 FACTORS AFFECTING WOODCOCK ACTIVITY ON THEIR SINGING GROWS O O O O O O O O O O O O O O O O O O O O O O O O 1 6 Time of Year . . . . . . 16 Tim Of Day a s a e e e e e e e e e e e a o e e e e e 0 18 Tmer‘ture e e e e s e e e e e e e e e s e a a e a e e 19 Prec 1p itat ion a e s a e e e e e e e a e e e e e e e e e 23 Wind Velocity . . . . . . . . . . . . . . . . . . . . . 23 FACTORS AFFECTING OBSERVATIONS OF SINGING-GROUND ACTIVITY .. 24 Wind Velocity . . . . 24 Inter ference O I O O O O O O O O O O O O 0 O O O O O O 24 Hearing variation . . . . . . . . . . . . . . . . . . . 25 ‘Miscellaneous Factors . . . . . . . . . . . . . . . . . 28 “mmATIONS Q Q Q Q Q 0 O O O O O O O O 0 O O O O O O I 29 8 WY 0 O O O I O O O O O O O O O O O O O O O 0 O O O O 0 3 o L ITEMTM c 1m 0 O O O O O O 0 O O O O O O O O O O O O O O 3 2 ”MIX 0 O O O O O O O O O O O O O I O O O O O O O O O O O 35 Factors Affecting Whodcock Spring Population Indexes in Southern Michigan INTRODUCTION Population inventories are important in all game management pro- grams. The only cheap and practical method known fer measuring spring population levels of American woodcock, Philohela m (Gmelin), is the count of males on their singing grounds (Trippensee, 1948). The courtship performance of the male woodcock occurs both at dawn and at dusk. It consists primarily of ground calls (peents) and flight songs (singing-ground flights), both of which are carried out from grassy openings among shrubs or trees. Such areas are called singing grounds. The standard inventory method (U.S. Fish and Wildlife Service, 1960) involves traveling by car over selected roads through territory which woodcock inhabit. The length of the route is 3-4 miles, depending upon the local length of period that woodcock actively perfonm their crepuscular courtship activities. Stops are at least 0.4 mile apart, with a 2-minute listening period at each stop. The observer listens for performing males and records the total number of individual birds heard. The purpose of this type of count is to obtain an index of population abundance under standardized conditions, so that comparisons can be made between routes and years to determine trends in the breeding population. No attempt is made to determine total population size. 1 Research on woodcock breeding habits has resulted in various modifications of the basic method for conducting singing-ground counts (Aldrich, 1954, 1955, 1956, 1957 and Robbins, 1958). The present study was undertaken in hopes of further improving the accuracy of woodcock counts. The objectives were to test the present standard method in southern Michigan and to determine the optimum conditions under which counts should be conducted. In an effort to accomplish the objectives, it was necessary to determine (1) whether fluctuations occurred in the number of woodcock heard different evenings on the same route, (2) the effects of various biological and climatological conditions on woodcock courtship activity, and (3) the factors affecting observers' abilities to hear the singing-ground performances. In 1954, 1955, and 1956, about thirty counts were conducted each spring on one or the other of two study routes. The standard method was followed, except that counts were made as many evenings as possible throughout the breeding season, regardless of climatic conditions. STUDY AREAS Michigan apparently leads all other states in the annual legal hunting-kill of woodcock (Blankenship, 1957). Migration data (Glasgow, 1957) and breeding range distribution maps (Mendell and Aldous, 1943) indicate that Michigan produces the majority of the woodcock killed within its boundaries. Two study areas were used, both located in the central section of southern Michigan (Figure 1). The Chendler Marsh area, five miles northeast (TSN, R2W) of Lansing, in southeastern Clinton County, was studied in 1954. In 1955 and 1956, singing-ground counts were conducted six miles further east, at the Rose Lake Wildlife Experiment Station (TSN, R13 and RlW) in Clinton and Shiawassee Counties. GLADWIN J HECOSIA ISABELLA MIDL AND TUSCOLA SANILAC sources tumor 5‘5“" GENESIS LAPEEN CLINTON mom ummu °”“'”‘° KALANAZN CALHOUN JACKSON WASHTENAVI CANADA 51 uouao: ‘ JOSEPH ./‘ LAKE O "" ERIE FIGURE 1 WOODCOCK SIMING-GROUND ROUTES AND SUPPLEMENTARY WEATHER STATIONS . Lansing Weather Bureau «on Chandler Marsh Route at East Lansing Weather Bureau ""1 Rose Lake Route FLUCTUATIONS IN SINGING-GROUND COUNTS variations in the number of woodcock heard during three breeding seasons on two singing-ground routes were considerable (Figures 2, 3, and 4). To test the significance of the observed fluctuations, analyses of variance using paired consecutive readings (Tables 1, 2, and 3) were performed euploying the following formula: Degrees of Sun of Mean Freedom Squares Square up" (DF) (88) (HS) Total in - 1 1x2 - lng Between 35 in - 1 {:13 gig-312 SS 2 - — DF Withi ‘“ as n Total DF Minus Total 33 minus 8 Run MS Between DF Between SS 57,- . ' "F" values for the three years were calculated as follows: 1 954 (DF) (38) (148) "F" Total (32»1) .. 31 44.2435 _ (53.25)? . 9.6947. 32 Between (16-1) - 15 86.5653 _ (33.2522 .-. 8.73385 .532257 9.70 n . 2 32 Within (31-15) - 16 9.6947 - 8.73385 8 0.96085 .060053 xx Highly Significant 1955 (DF) (33) (MS) "P" Total (28-1) 8 27 33-5345 _ M : 5 9332 28 ° 2 Between (14-1) - 13 2232223 _ 275:0 . 4.4137 .3395 3.13 x- Within (27-13) a 14 5.9332 - 4.4137 = 1.5195 .1085 {- Significant 1956 (DF) (33) (HS) "1"" Total (30-1) = 29 81.7425 _ (47.55)2 = 6.37575 30 Between (15-1) = 14 161.0425 _,(47.55)2 = 5.15450 .36818 2 30 4.52 xx Within (29-14) = 15 6.37575 - 5.15450 - 1.22125 .08142 X]! Highly significant Statistically highly significant differences were found between counts on the same route in 1954 and 1956, and differences at the significant level were obtained in 1955. The differences in the observed fluctuations, it was evident, were not likely to be due merely to chance. They were appraised from the standpoints of (1) variation in woodcock activity and (2) variation in the observer's ability to detect woodcock activity. TABLE 1 Paired Consecutive Reading Analysis of Variance 1954 Data Woodcock Woodcock heard/stop heard/stop 2 (X) (3') (x2) (3’ ) 2.17 . ‘ 4.7089 2.50 4.67 6.2500 21.8089 1.00 1.0000 1.00 2.00 1.0000 4.0000 0.67 0.4489 0.67 1.34 0.4489 1.7956 1.17 1.3689 1.33 2.50 1.7689 6.2500 1.67* 2.7889* 0.50* 2.17 0.2500* 4.7089 1.67* 2.7889* 1.50* 3.17 2.2500* 10.0489 1.50* 2.2500* 2.00* 3.50 4.0000* 12.2500 0.67* 0.4489* 0.67* 1.34 0.4489* 1.7956 0.50* 0.2500* 0.50* 1.00 0.2500* 1.0000 0.50* 0.2500* 0.50* 1.00 0.2500* 1.0000 1.40* 1.9600* 1.33* 2.73 1.7689* 7.4529 1.17* 1.3689* 1.33* 2.50 1.7689* 6.2500 1.00 1.0000 1.00 2.00 1.0000 4.0000 0.83 0.6889 0.83 1.66 0.6889 2.7556 0.50 0.2500 0.50 1.00 0.2500 1.0000 0.50 0.2500 0.17 0.67 0.0289 0.4489 ix: 33.25 5:2 : 44.2435 iyz = 86.5653 * These data were also used for determining confidence limits of the "Central Period", with the following values being obtained: N - 16 £23 = 23.0923 '1? s 1.09 (£::)2 -.- (17.41)2 = 303.1081 TABLE 2 Paired Consecutive Reading Analysis of variance 1955 Data Woodcock Woodcock Heard/stop Heard/stop 2 2 (x) (Y) (x ) (y ) 1.20 1.4400 1.60 2.80 2.5600 7.8400 1.60 2.5600 0.40 2.00 0.1600 4.0000 0.80 0.6400 1.20 2.00 1.4400 4.0000 1.00 1.0000 0.33 1.33 0.1089 1.7689 0.50 0.2500 0.67 1.17 0.4489 1.3689 1.17* 1.3689* 1.83* 3.00 3.3489* 9.0000 1.17* 1.3689* 1.67* 2.84 2.7889* 8.0656 1.67* 2.7889* 1.33* 3.00 1.7689* 9.0000 1.00* 1.0000* 1.00* 2.00 1.0000* 4.0000 1.17* 1.3689* 1.17* 2.34 1i3689* 5.4756 1 .338 1276898 1.33* 2.66 1.7689* 7.0756 0.50 5" 60.2500 0.50 1.00 0.2500 1.0000 0.50 0.2500 0.50 1.00 0.2 00 1.0000 0.33 0.1 '9 0.33 0.66 0.1089 0.4356 [x = 27.80 £182 : 33.5346 iyz : 64.0302 * These data were also used for determining confidence limits of the "Central Period", 2 with the following values being obtained: : 12 1.32 £112 . 21 .7090 (£102 . (15.84)2 . 250.9056 TABLE 3 Paired Consecutive Reading Analysis of Variance 1956 Data Woodcock Woodcock Heard/stop heard/stop 2 2 (x) (y) (x ) (y ) 1.75 3.0625 1.40 3.15 1.9600 9.9225 1.40 1.9600 1.40 2.80 1.9600 7.8400 1.40 1.9600 1.00 2.40 1.0000 5.7600 1.40 1.9600 1.00 2.40 1.0000' 5.7600 1.00 1.0000 1.00 2.00 1.0000 4.0000 1.20 1.4400 1.00 2.20 1.0000 4.8400 1.808 3.24008 2.208 4.00 4.84008 16.0000 1.608 2.56008 2.008 3.60 4.0000*- 12.9600 2.208 4.8400*' 2.208 4.40 4.84008 19.3600 2.008 4.00008 1.208 3.20 1.44008 10.2400 2.208 4.84008 2.20* 4.40 4.8400* 19.3600 2.008 4.00008 2.008 4.00 4.00008 16.0000 2.008 4.00008 2.008 4.00 4.00008 16.0000 1.208 1.44008 1 .80* 3 .00 3 .24008 9 .0000 1.40 1.9600 0.60 2.00 0.3600 4.0000 {x . 47.55 5.2 = 81.7425 {,2 = 161.0425 * These data were also used for determining confidence limits of the "Central Period", with the following values being obtained: N . 16 £32 = 60.1200 ii . 1.91 ({3.)2 = (30.60)2 . 936.3600 FIGURE 2 1954 FLUCTUATIONS IN THE NUMBER OF WOODCOCK HEARD PER STOP, WITH THE "CENTRAL PERIOD" AND CONFIDENCE INTERVAL FOR THE MEAN OF THE "CENTRAL PERIOD" INDICATED . Woodcock Heard Per Stop Fluctuations In The Number Of Woodcock Heard Per Stop Limits Of The "Central Period" Mean Of The "Central Period" Limits Of The Mean (Confidence Limits) 10 BIRDS PER 8202' .Hu T __-__L__ :L: onzawbh wNwHQU 1 Home bwer HQ an :>& Hm OOZNHUNznn L. T._.:.:_ :_ HZHHN<>H new .ano# a... we benwp wm -nwm 1* ._ __ .h“ _ , we mew _____p_______o .p. to E M .4 meme FIGURE". 3 1955 FLUCTUATIONS IN THE NUMBER OF WOODCOCK HEARD PER STOP, WITH THE "CENTRAL PERIOD" AND CONFIDENCE INTERVAL FOR THE MEAN OF THE "CENTRAL PERIOD" INDICATED s Woodcock Heard Per Stop Fluctuations In The Number Of Woodcock Beard Per Stop : Limits Of The "Central Period" ...;..|...".._Mean Of The "Central Period" _ _ 1... Limits Of The Mean (Confidence Limits) 12 BIRDS PER STOP New“ 1 ”be ”0““ j N.HO1 H.om.. H.mol How. H.mo . / H . um OOZNHUMZON H . no Hzamwfifl. H.ou .oo ong wmeO—u 1 Houm .ao Burn—“H. H» 11 ZEN HN .3 .8 W A .HmT :E:EEE.:2;E_____::E:rEFrEréEx: no H w H». NH Nm H w H». NH N@ H 32.66 23.5 33. home FIGURE 4 1956 FLUCTUATIONS IN THE NUMBER OF WOODCOCK HEARD PER STOP, WITH THE ”CENTRAL PERIOD" AND CONFIDENCE INTERVAL FOR THE MEAN OF THE "CENTRAL PERIOD" INDICATED a ' Woodcock Heard Per Stop Fluctuations In The Number of Woodcock Heard Per Stop : Limits Of The "Central Period" I Mean Of The "Central Period" .. _. _. Limits Of The Mean (Confidence Limits) l4 BIRDS PER STOP ~.u N.» ~.N N.H H.o H.m H.m H.u H-u H.» H00“ \Nhulfilln 1| II null 85.3.9sz . HZHmw<>F ONZHN>H wmeOU 1 mem >wer mm 11 :>& Nu l _ no manor __t::::.::_:__:_r::LFL:13:;..:_:_I_E:__ H a. a. M Mm H a E- a . ”a 4 - bmnHH xmw memo FACTORS AFFECTING WOODCOCK.ACTIVITY ON THEIR SINGING GROUNDS TIME OF YEAR - Hale woodcock courtship performances begin each spring as soon as they have returned to the breeding grounds, and they continue through the nesting period (Edminster, 1954). Blankenship (1957) found the major nesting effort and main portion of the breeding activity oc- curring in the last two weeks of April and first two weeks of‘May in the Lower Peninsula of Michigan. However, Edminster (1954) stated that the time of nesting depends on whether the spring season is early or late. On the study areas of this investigation, the courtship period each year extended from the last week in March through the first week in June. Gradually-increasing numbers of migrants and cessation of breeding, respectively, seemed likely to be largely responsible for the variation in numbers of woodcock heard at the beginning and end of each breeding season. In order that counts would not be influenced unduly by variation due to this progression of the breeding season, a "central period" was established. It was determined separately for each of the three years so as to include the 30-day period of courtship activity ‘with the most consistent series of counts. The beginning of this re- latively consistent period varied each spring (Figures 2, 3, and 4), thus agreeing with Edminster's statement relating the time of nesting to seasonal factors, and supporting Kendall and Aldous' (1943) view that the hatching season is directly correlated with weather conditions. unless otherwise noted, analysis of the remaining factors affecting woodcock indexes involves only those counts conducted within the "central period". 16 For each of the three years, confidence limits were determined for the mean number of woodcock heard per stop for counts conducted during the "central period" (Tables 1, 2, and 3). Confidence limits were accepted as i t .683; where E is the mean of the "central period" and s is the standard deviation of the counts. This method, derived from Snedecor (1946), established limits within which half of the ob- servations (counts) would fall: Variance (mean square): s : Standard deviation: 3 = V 82 Confidence limits: 3(- i .688 Confidence limits for the three years were calculated as follows: 1954 2 23.0923 - M Variance (s ) : l6-1 15‘ z .2765 Standard deviation (8) = V0.2765 .5258 Confidence limits I 1.09 + (.68 x .5258 3 .36) a 1.45 : 1.09 - (.68 x .5258 .-. .36) = 0.73 17 1955 21.7090 _ 250.9056 variance (32) = 12 = .07275 12-1 Standard deviation (3) - ‘¢.07275 = .2697 Confidence limits 1.32 + (.68 x.2697 m .18) a 1.50 1.32 - (.68 x .2697 = .18) e 1.14 1956 60.1200 - 936.3600 Variance (32) a 16 . .10667 16-1 Standard deviation (s) - V.10667 . .3266 Confidence limits - 1.91 + (.68 x .3266 . .22) a 2.13 1.91 - (.68 x .3266 s .22) = 1.69 TIME OF'DAY - woodcock are affected by variation in light during their crepuscular courtship periods (Hendall and Aldous, 1943). Cloud cover and phase of the moon are two factors causing daily variation in light conditions at dawn and dusk. The percentage cloud cover and moon phase were estimated and recorded in the field at the time of the first singing-ground flight. Any changes in the amount of cloud cover present during the count were also noted. Offical phases of the moon were ob- tained from1"The Systementry Year Book" (Anonymous, 1954, 1955, 1956). The time interval between official sunset and first flight from the singing ground varied from 8 to 34 minutes on the basis of 34 ob- servations. The mean and median of these time intervals were computed and an average interval obtained. Average time intervals in relation 18 to percentage cloud cover at the time of first flight were: 27 minutes at 0-301 cloud cover, 23?; minutes at 35-65%, and 19 minutes at 70-1001 (Figure 5). Hendall (1955) has stated that woodcock were very inconsistent in performing during the period two days before a full moon and one day afterwards. Counts conducted during the full moon period of this study, however, were not inconsistent. Six counts were conducted during the full moon period with an average cloud cover of less than 351. Only one of these counts fell outside the confidence limits of the mean, and it is probable that low temperature was more important than moon- light in causing the decrease in woodcock heard that evening. various investigations, including this one, have revealed that woodcock begin their courtship activities later and continue longer with a bright moon overhead. During the 30 minutes immediately following the first singing- ground flight, however, no inconsistency due to a full moon was ob- served . TEMPERATURE - This factor was found to be the most iuportant of the several climatological elements‘affecting woodcock courtship activity. In 1954, temperatures were not recorded in the field but were ob- tained from the U. 8. Weather Bureau at the Capital City Airport, Lansing, approximately five miles west of the study area. In 1955 and 1956, temperatures were recorded at the beginning of each count with a Taylor binoc-type thermometer held four feet above the ground at roadside. Of 55 conparable couparisons with airport weather records in 1955 and 1956, 52 were higher (averaging 3.5°F. increase) than the field-recorded tenperatures. To render the temperatures for the three 19 FIGURE 5 TIME INTERVAL BETWEEN FIRST SINGING-GROUND FLIGHT AND OFFICIAL SUNSET IN RELATION TO PER CENT OF CLOUD COVER PRESENT AT THE TIME OF THE FIRST FLIGHT . Individual (Daily) Comparisons Median Time Interval (Minutes) For Each Percentage Cloud Cover Group I _ Mean Time Interval (Minutes) For Each Percentage Cloud Cover Group 20 1.1191121 (INHONO DNIDNIS $81115 1210 M1 IV 1131100 011010 EOVLNRDNfld MINUTES BETWEEN OFFICIAL SUNSET AND FIRST SINGING GROUND FLIGHT H H N U o 01 o U1 U1 o I N l T l I 9 as. .o 1» DUI a 0 coo I e b) u: 1 l 0‘ o o :0 .00 UI N I . ‘1:> O a easel o ' o 1-- l . o o o " SE years comparable, therefore, those of 1954 were reduced three degrees each. The U. S. Fish.and Wildlife Service (1960) instructed that counts not be made when the temperature was below 25°F. During this study, however, whenever air temperatures along the roadside were below 41°F. at the time of the first singing-ground flight, the number of woodcock heard was less than the lower confidence limit of the mean (Figure 6). ,This occurred five times within the "central period". Low temperatures, ‘moreover, may well have been the primary climatological factor limiting courtship activity prior to the "central period" (Figures 2, 3, and 4). During the 1955 study, additional air temperatures were recorded at the conclusion of eight counts on one actively occupied singing ground and at the nearby roadside. Temperatures on the singing ground in this experiment were measured three inches above the sod. Here, temperatures averaged nine degrees lower than corresponding roadside temperatures and eleven degrees below the roadside temperatures recorded 30 to 35 minutes earlier at the beginning of the counts. Since air temperatures at the roadside may be considerably higher than air temperatures on singing grounds and since they normally decrease as the evening progresses, the minimum roadside temperatures for conducting counts should be set high enough to insure normal courtship activity along the entire route. Temperatures above 40° F. at roadside seem to be required,’ PRECIPITATION - Rain and snow were encountered so infrequently while con- ducting counts that no new information was obtained. Blankenship (1957) 22 determined that rain and snow reduced singing-ground activity more or less directly; Edminster (1954) stated that woodcock.are very active in light mist on warm nights, though Kendall and Aldous (1943) found that heavy fog or mist curtailed much of the singing-ground activity during cold temperatures. Aldrich (1954) recommended that counts for the Fish and Wildlife Service not be made in heavy rain or snow. WIND VELOCITY - Pettingill (1936) concluded that winds apparently have little effect on breeding activities. Edminster (1954) and Kendall and Aldous (1943), however, stated that strong winds reduce or en- tirely curtail courtship activity. Robbins (1954) found that winds above five miles per hour invariably reduce winnowing activities of the related Wilson's snipe. Blankenship (1957) stated that woodcock activity becomes erratic when wind velocities reach 13-18 miles per hour. Observations during this study indicated that woodcock peented actively but flew less when wind velocities were above 15 miles per hour. Wind also affected the observer's hearing ability (see beyond). 23 FACTORS AFFECTING OBSERVATIONS OF SINGING-GROUND ACTIVITY WIND VELOCITY - Blankenship (1954) found that on windy evenings the hearing distance of "peents" was greatly reduced. The U. 8. Fish and Wildlife Service (1960) stated that a wind velocity of 8-10 miles per hour was too strong for conducting singing-ground counts. The present investi- gation, however, does not entirely support this contention. During this study, wind velocity was estimated at every stop by the Beaufort Wind Scale observation method (Americana Encyclopedia, 1956). On the five evenings when the average wind velocity was 15 or more miles per hour, the number of woodcock heard was less than the lower confidence lumit of the mean (Figure 6). Thirteen counts were conducted with an average wind velocity above eight and less than 15 miles per hour. Results from six of these counts were above the upper confidence limit of the mean and six other counts were within the accepted confidence limits. The only count to fall below the lower confidence lbmit of the mean occurred when it was also true that the roadside air temperature was 36° F. at the time of the first singing-ground flight (Figures 2, 3, 4, and 6). INTERFERENCE - Disturbances other than wind velocities often seemed to decrease the observer's ability to hear courtship activity. Such inter- ference originated from.highway traffic, trains, airplanes, farming operations, frogs, dogs, birds, mosquitoes, etc. The following scale was developed and the amount of interference was recorded at each stop along the route. 24 Interference Scale Description Rank Noises of short duration or of light intensity. Listening period disrupted up'to 30 seconds. 1 Appreciable disruption, such as a car passing during count. Listening period shortened be- tween 31 and 60 seconds. . 2 Disruption of such intensity or duration that woodcock courtship activity might not be heard. Difficulty encountered by observer in concen- trating on the objective. Listening period shortened by 61 to 90 seconds. 3 Interference such that it is impossible to hear woodcock performing. (Train, tractor, etc. located very near stop.) Listening period dis- rupted from 91 seconds to the end of the 2~minute period. Data from such locations should be eliminated from analysis. 4 Whenever the average interference for a route totalled above 2.25 on this scale, the number of woodcock heard on that route was below the lower confidence lhmit of the mean (Figure 6). HEARING VARIATION - Since individual hearing ability varies considerably (Dorney gtflgl., 1958) and since hearing differences have been noted among observers on pheasant crowing cock counts (Carney and Petrides, 195?), experiments were conducted to detenmine whether variation in hearing courting males occurred among woodcock observers. These tests were not designed for statistical analysis, but three individuals tested were unable to hear woodcock ground activity (peenting) over 65 yards away. One of these apparently could not pick up the frequency pitch at any distance. Variation among 18 other individuals, including six ex- perienced observers, however, was negligible. 25 FIGURE 6 SCATTERGRAH COMPARISONS BETWEEN INTERFERENCE, TEMPERATURE, WIND VELOCITY AND COUNTS ‘x Counts Below the Lower Confidence Limit Of The Dean. . Counts Above Or Within The Mean's Range. (MPH) Wind Velocities Considered Critical (15 or more Mi./Hr.). l— - — -1 Within Box: Counts Conducted With Average Temperatures .L. I Above 40°F. And The Interference Average Less Than 2.25. A11 Were Above Or Within The Confidence Limits Of The Kean, Except For Counts During Which The Average Wind Velocity Was 15 Or More Miles Per Hour. I l l l : Outside Box: Counts Conducted With Average Temperatures I , Below 40°F. And The Interference Average I :More Than 2.25. All Of These Counts Were I Below The Lower Confidence Limit Of The — — — -J Mean. 26 TEMPERATURE amfi ab! 3 .. me- me u... x 3.3 x 33 L . . N . No Hzamwmdwmzow LI ~.oo b P p r F b F P p ”Two v.9.» Hike BIND 'HISCELLANBOUS PhCTORS - Wbodcock are promiscuous and males occasionally change singing grounds (Sheldon, 1953). However, Sheldon and Blanken- ship (1957) both found that these vacated locations were usually promptly occupied by another male. Blankenship (1957) cited several instances of courting males being disturbed by farming activities or by other animals nearby. He indi- cated that this may cause erratic courtship activity or a temporary change in singing-ground location. RECOMNDATIONS On the basis of this study, the following recomndations are sug- gested for standardization of woodcock singing-ground counts in southern Michigan : 1. 2. Counts should be made during the period April 20 - May 10. Counts should be limited to the 30 minutes immediately following the first singing-ground flight. Roadside air temeratures should be above 40° F. at the time of the first singing-ground flight. Wind velocities should be less than 15 miles per hour. When the interference index is 4 for a single stop or above 2.25 average per stop for the total route, the data for that stop or route should be eliminated from analysis. 29 SUMMARY American Woodcock (Philohela minor) spring population-level es- timates counonly are determined from roadside counts of males on their singing grounds. This study was undertaken to attenpt improvement in the accuracy of these index counts. In 1954, 1955, and 1956, an average of thirty counts were con~ ducted each spring on one or the other of two southern Michigan singing- ground routes. Statistically significant differences were found among many of these counts. The causes of this variation were ascertained by determining (1) the effect of various biological and climatological conditions on woodcock courtship activity, and (2) the factors af- fecting observers“ abilities to hear the singing-ground performance. Singing-ground counts in southern 'Michigan were found to be most consistent during the annual period April 20 - May 10, coinciding with the peak of courtship and nesting seasons. Commencement of evening singing-ground performances was determined by the time of sunset as related to the percentage of cloud cover. By limiting counts tothe 30 minutes imediately following the first singing- ground flight, inconsistencies from the effects of moonlight were avoided. Reduced courtship activity was invariably observed when air teuperatures at the roadside were 40° F. or below at the begin- ning of the count. Variation among observers in hearing singing- ground activity was slight. The ability of observers to hear wood- cock, however, was appreciably reduced when wind velocities were 15 miles per hour or more and when other sources of noise were too long or intense. 30 Recounendations based on the above findings were suggested for standardisation of woodcock singing-ground counts in southern Michigan. 31 LITERATURE CITED Aldrich, John W. 1954. Smary of 1953 woodcock, snipe and rail investigations. Special Scientific Report - W11dlife Ho. 24: 1-8. U. 8. Fish and Wildlife Service, Washington, D.C. . 1955. Summary of investigations of wbodcock, snipe, and rails in 1954. Special Scientific Report - Wildlife Nb. 28: 1-6. U. 3. Fish and Wildlife Service, Washington, D.C. . 1956. Summary of woodcock, snipe and rail in- vestigations for 1955. Special Scientific Report - Wildlife no. 31: 1-6. U. 8. Fish and Wildlife Service, Washington, D.C. . 1957. Perspective of woodcock, snipe and rail investigations - 1956. Special Scientific Report - Wild- life No. 34: 1-8. U} S. Pish.and Wildlife Service, Washington, D.C. Americana Encyclopedia. 1956 ed. Volume 3, pages 389-390. American Book - Stratford Press Inc., New Yerk. Anonymous. 1954, 1955, 1956. The systemetry year book. Shedd- Brown, Menneapolis, Minnesota. Blankenship, Lytle H. 1954. Investigations on woodcock in Michigan. Special Scientific Report - Wildlife No. 24: 41-48. U. S. Fish and Wildlife Service, Washington, D.C. 32 . 1957. Investigations of the American woodcock in Michigan. Michigan Department of Conservation - Game Division - Final Report Number 2123, 217 pages. Carney, Samuel M. and George A. Petrides. 1957. Analysis of variation among participants in pheasant cock-crowing censuses. The Journal of Wildlife Management, 21 (4): 392-397. Dorney, Robert 8., Donald R. Thompson, James B. Hale, and Robert F. Wendt. 1958. An evaluation of ruffed grouse drulmaing counts. The Journal of Wildlife Management, 22(1): 35-40. - Edminster, Frank C. 1954. American game birds of field and forest Charles Scribner's Sons, New York, pages 392-414. Glasgow, Leslie L. 1957. Preliminary analysis of woodcock band returns. Special Scientific uport - Wildlife No. 34: 51-55. U. 8. Fish and Wildlife Service, Washington, D.C. Mendall, Howard L. 1955. Woodcock census studies in northeastern United States - 1954. Special Scientific Report - Wildlife No. 28: 13-18. U. S. Fish and Wildlife Service, Washington,D.C. and C. M. Aldous. 1943. The ecology and manage- ment of the American woodcock. Maine Cooperative Wildlife Re- search Unit, Orono, Maine, 201 pages. Pettingill, Olin 8., Jr. 1936. The American woodcock, Philohela m_in_o_r_ (Gmelin). Mem. Boston Soc. Nat. History, 9(2): 169-321. Robbins, Chandler S. 1954. Further investigations on winnowing method of measuring Wilson's snipe populations. Special Scientific Re- port - Wildlife No.24:61-66. U. S. Fish and Wildlife Service, Washington, D .C . 33 . 1958. Woodcock newsletter. Issue No. 1. (28 page mimeographed report) U. S. Fish and Wildlife Service, Washington, D.C. Sheldon, William G. 1953. Woodcock studies in Massachusetts. Trans. North American Wildlife Conference, 18: 369-377. Snedecor, George W. 1946. Statistical methods. Iowa State College Press, Ames, Iowa9 4th edition, 485 pages. Trippensee, [tsuben B. 1948. Wildlife management. McGraw-Hill Book Company, Inc., New York. Volume I, pages 323-332. U. S. Fish and Wildlife Service. 1960. Instructions for the censusing of woodcock, 1960. (mimeographed, 5 pages) Washington, D.C. 34 APPENDIX WOODCOCK SINGING GROUND DATA - - 1954 DATE TEMPERATURE WIND VELOCITY INTERFERENCE BIRDS BIRDS HEARD HEARD of Beginning Average Average Per Count of Count* During Count During Count Total Stop April 5 49 -- -- 13 2.17 " 6 56 9 -- 15 2.50 " 8 32 2 -- 5 1.00 " 9 43 w- -- 6 1.00 " 12 42 13; -- 4 0.67 " 13 57 2‘ 1.5 4 0.67 " 14 64 2 -- 7 1.17 " 15 66 13 -- 8 1.33 " 20 48 10 2.2 10 1.67 " 22 47 2 2.4 3 0.50 " 23 45 4 1.7 10 1.67 " 26 59 9 1.6 9 1.50 " 28 47 2 1.2 9 1.50= " 29 51 2 1.4 12 2.00 Mhy 3 31 16 1.0 4 0.67 " 4 37 15 1.2 4 0.67 " 5 33 7 1.2 3 0.50 " 6 43 3 3.2 3 0.50 " 7 38 4 2.4 3 0.50 " 11 45 16 1.7 3 0.50 " 13 52 2 1.4 7 1.40 " 16 58 2 2.0 8 1.33 " 17 49 4 2.2 7 1.17 " 18 50 73 2.0 8 1.33 " 19 43 8 2.0 . 6 1.00 " 21 53 6 1.7 6 1.00 " 23 61 2 1.7 5 0.83 " 24 63 11 1.8 5 0.83 " 25 52 2 2.5 3 0.50 " 26 56 10 1.8 3 0.50 " 27 57 17 1.3 3 0.50 " 28 68 19 1.0 1 0.17 *Information obtained from the united States Department of Commerce, Weather Bureau, Lansing, Michigan (Capitol City Airport - Latitude 42° 47' 11.; Longitude 84° 36' w.; Ground Elevation 859 feet). The temperatures at the beginning of the counts have been corrected (reduced 3 degrees) to field temperatures. 36 WOODCOCK SINGING GROUND DATA - - 1954 DATE PRECIPITATION CLOUD COVER MDON** BIRDS BIRDS (L) M of Daily During Beginning Full . Per Count Tota1* Count of Count Period Tots Stop April 5 0 0 - 13 2.17 " 6 0.21 0 100 15 2.50 " 8 T O 0 5 1.00 " 9 O 0 100 6 1.00 " 12 0 O 0 4 0.67 " 13 0 O 70 4 0.67 " 14 0 0 50 7 1.17 " 15 0.67 0 90 plus 2 8 1.33 full (17th) " 20 0.43 0 100 10 1.67 " 22 0.05 0 - 3 0.50 " 23 0 O 0 10 1.67 " 26 0.66 0 50 9 1.50 " 28 T 0 160 9 1.50 " 29 T 0 25 12 2.00 May 3 0.02 T 50 4 0.67 " 4 0.03 0 100 4 0.67 " 5 T 0 90 3 0.50 " 6 T 0 60 3 0.50 " 7 0 0 0 3 0.50 " 11 0.01 0 100 3 0.50 " 13 0 0 20 7 1.40 " 16 O 0 20 plus 1 8 1.33 " 17 0 0 20 full ' 7 1.17 " 18 T 0 90 minus 1 8 1.33 " 19 0 0 0 6 1.00 " 21 0 0 10 6 1.00 " 23 O 0 30 5 0.83 " 24 0 0 90 5 0.83 " 25 0 O 30 3 0.50 " 26 0 0 100 3 0.50 " 27 0.04 T 100 3 0.50 " 28 T 0 80 1 0.17 *Information obtained from the United States Department of Commerce, Weather Bureau, East Lansing, Michigan. (Latitude 42° 44' N.; Longitude 84° 29' W.; Ground Elevation 856 feet). **Dates of the full moon obtained from.The Systementry Year Book, 1954, published by Shedd-Brown, Minneapolis, Minnesota. 37 MISCELLANEOUS CLIMATOLOGICAL DATA -- 1954* APRIL: Temperature (°F): Precipitation (In.): Monthly Average = 48.5 Monthly Total = 2.75 Departure From Normal = +3.2 Departure From Normal =-0.08 This April was the warmest April since 1948, with an average tenperature 3.2° above normal. Total snowfall for the month of 0.1 inches was 2.6 inches below normal. MAY: Temperature (°F): Precipitation (In.): Monthly Average - 53.0 Monthly Total -.- 1.14 Departure From Normal -.-. -3.5 Departure From NOMI : -2.61 This May was 3.50 below normal in tenperature, making it the coldest May since 1947. Precipitation was 2.61 inches below normal. Up to the 3lst, only 0.34 inches had occurred. Had we not had 0.80 inches on the 3lst, this May would have been the third driest May since the beginning of record and the sixth driest of any month since 1900. fInformation obtained from the United States Department of Com- merce, Weather Bureau, Lansing, Michigan'(Capit01 City Airport - Latitude 42° 47' N.; Longitude 84° 36' W.; Ground Elevation 859 feet). 38 WOODCOCK SINGING GROUND DATA - - 1955 BIRDS HEARD Per' Sto BIRDS WIND VELOCITY INTERFERENCE DATE TEMPERATURE Total Average Count Average Duri Count Dur Beginning of Count of Count “000 7737773 7733000033 oaaoao oaaaooaaamo 1I100L1000001111111111110°00 o [+66227773200572530805702358 -aaaa000.000.000.000000000000 .111222112222112222121121111 22250199973143334.222212592262 11...... 1. 1 1.1.1 1 1. 39 WOODCOCK.SINGING GROUND DATA - - 1955 ‘DATE PRECIPITATION CLOUD COVER nrxnrhk BIRDS BIRDS ' 519g BEARD BEARD of Daily During Beginning Pull Per Count Total* Count of Count Period Total Stop March 29 0 0 0 6 1.20 " 30 0 0 0 8 1.60 " 31 0 0 0 8 1.60 April 2 0 0 40 2 0.40 " ,3 0 0 10 4 0.80 " T4 0 0 90 6 1.20 " 5 0.03 0 5 plus 2 6 1.00 " 6 T 0 100 plus 1 2 0.33 " 7 T 0 10 full 3 0.50 " 8 0 0 5 minus 1 4 0.67 " 12 0.09 0 30 7 1.17 " 13 0.03 0 40 11 1.83 " 14 0 0 80 7 1.17 " 18 0.14 0 85 10 1.67 " 20 0.04 0 60 10 1.67 " 22 0 0 5 8 1.33 " 27 0 0 0 6 1.00 " 28 0 0 5 6 1.00 " 30 0 0 5 7 1.17 May 3 0 0 10 7 1.17 " 5 0 0 0 plus 1 8 1.33 full 6th " 11 ‘0 0 30 8 1.33 " 13 0 0 80 3 0.50 " 14 0 0 0 3 0.50 " l7 0 0 0 3 0.50 " 20 0 0 0 3 0.50 " 24 0.34 T 100 2 0.33 June 1 0 0 5 2 0.33 *Information obtained from the united States Department of Commerce, Weather Bureau, East Lansing, Michigan. (Latitude 42° 44' N.; Longitude 84° 29' W.; Ground Elevation 856 feet). **Dates of the full moon ‘obtained from The Systementry Year Book, 1955, published by Shaddrhrown, Minneapolis, Minnesota. 40 MISCELLANEOUS CLIMATOLOGICAL DATA -- 1955* APRIL: Teuperature (°F): Precipitation (In.): Monthly Average : 54.5 ' Monthly Total = 41.56 Departure Prom Normal : +9.2 Departure Prom Normal : -1.27 April, 1955 was the warmest April since 1864. Temperatures were above normal every day except three. Previously, the warmest April occurred in 1896 when the monthly average was 52.6 degrees. MAY: Temperature (°F): Precipitation (In.): Monthly Average = 61.0 Monthly Total : 1.53 Departure Prom Normal : + 4.5 Departure Prom Normal 2 -2.22 O Considerably above normal temperatures and below normal precipitation continued for the second month in a row. Total accumulated deficit in rainfall for April and May amounted to 3.49 inches while it was the warmest May since 1922. * Information obtained from the United States Department of Com- merce, Weather Bureau, East Lansing, Michigan (Latitude 42° 44' N.; Longitude 84° 29' 11.; Ground Elevation 856 feet). 41 WOODCOCK.SINGING GROUND DATA - - 1956 DATE TEMPERATURE WIND VELOCITY INTERFERENCE BIRDS 7 IBIRDS - ggggy HEARD ' of Beginning Average Average Per Count of Count During Coggt During Count Total Stop April 2 55 2 2.0 7 1.75 " 11 46 6 2.2 7 1.40 " 12 40 12 2.0 7 1.40 " 14 56 14 1.4 7 1.40 " 15 40 7 1.6 7 1.40 " 16 37 23 1.4 5 1.00 " 17 34 20 1.6 7 1.40 " 19 36 17 1.8 : 5 1.00 " 20 38 11 1.6 5 1.00 , " 21 44 8 1.6 5 1.00 " 23 33 2 2.6 6 1.20 " 24 35 2 2.4 5 1.00 " 26 46 2 2.2 9 1.80 " 30 41_ 2 1.8 11 2.20 May 1 50' 15 2.2 8 1.60 " 3 50 4 1.8 10 2.00 " ‘4 49 5 1.8 11 2.20 " 7 46 12 1.8 11 2.20 " 8 46 10 1.6 10 2.00 " 9 62 25 1.4 6 1.20 " 14 54 2 2.0 11 2.20 " 15 52 6 2.0 11 2.20 " 17 42 12 1.8 10 2.00 " 18 60 13 2.0 10 2.00 " 20 49 10 2.0 10 2.00 " 21 64 2 2.0 10 2.00 "' 23 36 11 1.4 6 1.20 " 24 42 2 2.0 9 1.80 " 28 60 2 1.7 7 1.40 June 4 52 3 1.8 3 0.60 42 WOODCOCK SINGING GROUND DATA.- - 1956 I noon" BIRDS amps DATE PRECIPITATION CLOUD COVER (:2 M of Daily During Beginning Pull Per Count fl Tota1* Count of Count Period Total Stop April 2 0.15 0 100 A 7 1.75 " 11 0 0 10 7 1.40 " 12 T 0 10 7 1.40 " 14 0.07 0 25 7 1.40 " 15 0 0 100 7 1.40 " 16 0.04 0 100 5 1.00 " 17 0.09 T 100 7 1.40 " 19 0 0 5 5 1.00 " 20 O 0 10 5 1.00 " 21 T 0 15 5 1.00 " 23 0 0 20 ‘minus 1 6 1.20 " 24 0 0 10 full 5 1.00 " 26 0 0 85 9 1.80 " 30 T 0 5 11 2.20 May 1 0 0 50 8 1.60 " 3 0.05 T 100 10 2.00 " 4 0.58 0 10 11 2.20 " 7 0 0 5 11 2.20 " 8 0 0 0 10 2.00 " 9 1.76 0.02 100 6 1.20 " 14 0 0 60 11 2.20. " ‘15 0.43 0 100 11 2.20 " 17 0.15 0 100 10 2.00 " 18 0.01 0 25 10 2.00 " 20 0.01 0 95 10 2.00 " 21 T 0 20 10 2.00 " 23 0 0 0 minus 1 6 1.20 " 24 0 0 70 full 9 1.80 " 28 0 0 5 7 1.40 June 4 T 0 20 3 0.60 *Information obtained from the United States Department of Commerce, Weather Bureau, East Lansing, Michigan. (Latitude 420 44' N.; Longitude 840 29' W.; Ground Blevatidn 856 feet). **Dates of the full moon obtained from.The Systementry Year Book, 1956, published by Shedd-Brown, Minneapolis, Minnesota. 43 MISCELLANEOUS CLIMATOLOGICAL DATA -- 1956* APRIL: Teamerature (°F): Precipitation (In.): Monthly average a 44.6 Monthly Total = 4.27 Departure From Normal - -0.7 Departure From Normal - +1.44 April, 1956 was 10 degrees colder than April of last year. The . . first six days averaged 13 degrees above normal while the last 24 days averaged 4 degrees below normal. Rain on the 27th through 29th, totaling 3.25 inches, was the heaviest since May 10-12, 1948, when 3.28 inches fell. MAY: Temperature (°F): Precipitation (In.): Monthly Average = 56.4 Monthly Total = 5.60 Departure From Normal : -0.1 Departure From Normal : +1.85 May, 1956 had above normal rainfall for the second month in a row. Tornado alerts were issued on the 11th, 12th and 13th. I *Information obtained from the United States Department of Comerce, Weather Bureau, East Lansing, Michigan (Latitude 42° 44' N.; Longitude 84° 29' W.; Ground Elevation 856 feet). Instructions for the Censusing of Woodcock, 1960 I. Introduction, (Some changes in Section I since 1959) Whodcock can be censused.most easily by counting the number of males heard calling along a given length of road running through territory which woodcock inhabit during the breeding season. The purpose of this type of census is to Obtain an index of popula- tion abundance in the region sampled, not to determine the total popula- ‘tion in any area. The principle involved is to make the Observations as standardized as possible both as to time and space, so that they will be comparable with results Obtained in different regions and in different years. To accomplish this, trips are made over a given route. Stops §£g_ always made at the same place and of definite duration. The number of birds heard calling per stop per route is taken as the index of abundance for that particular areas With these Objectives in.view'and considering all that has been learned to date of woodcock'behavior and the prOblems of recording their calls, the following standard method has been decided upon. If for any reason you will be unable to cover last year's route, please notify your coordinator before April 1. II. Locating the Census Area Careful consideration should be given to locating the census area. Since the count can.be made most effectively'by using an automObile, a driveable route will necessarily need to be selected. .A stretch of road bordered by numerous alder runs, open young mixed growths, or young hard- wood stands (especially where numerous small openings, fields or pastures occur) prObably will yield counts representative of the best type of wood- cock cover. A.few scattered houses along the road will not detract from the suitability of the census route. However, care should be taken to avoid areas where excessive noises will occur, such as small settlements, heavily traveled highways, and series of small ponds or dr ainage ditches which are likely to contribute noisy choruses of frogs. III. Length of the Census Route The length of your route should be based on the distance that can be covered during the minimum time woodcock have been observed calling in your area. If there is any doubt on this point use the arbitrary time of thirty minutes. The length of the route will vary with woodcock popula- tion densities. With discontinuous habitat and a low population it may be possible to cover more than 4 miles, whereas in areas of high concentra- tion 3 miles may'be all that can be covered. If a route longer than can be covered during the singing period in one evening is available it may be divided into two or more individual routes and covered in separate even- ings. ~~¢miiiilinanll IV. Taking the Census (Some changes in Paragraph 2 of Section IV since 1959) 1. Note to beginners.--To those who are wholly unfamiliar with the courtship behavior of the woodcock and the census technique it is sug- gested that they spend some time (in the field particularly) with.one experienced person.before starting out on their own. 2. Time of year to start the census.--The time of the year the census should be started will vary with the locality and region. Weed- cock.being migratory will visit states south of New England, and equiva- lent areas to the west, much earlier than.Maine or northern.Minnesota, for example. The census work.should.be carried out after migration.has ceased in a given locality and before the peak of the hatching period. For example, in Pennsylvania the period.April 6-26 is about right. States south of Pennsylvania or equivalent areas would need to start earlier, and the most northerly areas of the United States and adjoining sections of southern Canada would start no earlier than the latter part of April. 3. Time of day to start the census.--The census data are collected during the evening period. The average male woodcock begins to "sing" at about ten to thirty minutes after sunset, depending on weather conditions. The period during which woodcock perform on their singing grounds varies from about twenty minutes to about forty-five minutes, averaging about thirty—five minutes in length. It would be most desirable for the first stop (or starting point) to be at a point where a woodcock is likely to be heard so that the starting time for any given evening's count may be accurately determined. 4. How to choose a starting point and interval stops.--Besides start- ing at a point where a woodcock is known to sing regularly, the starting point should be as distinct a land feature as possible, such as a railroad " crossing, a culvert, a bridge, a crossroad, etc. Subsequent listening points should be no closer than four-tenthsof a mile apart. Intervals between stops may be increased to the extent necessary to avoid nonwood- cock habitats or exceptional disturbances. 5. Number of times to make the counts.--Preliminary statistical studies of this census method indicate that it is preferable to run more routes once than fewer routes more than once. If, however, there is reason to believe that conditions were not normal on the night the route 'was run, it would.be advisable to repeat the coverage another night as a check. DI' '- QW‘MW...‘ :ar ‘ . “..‘-.'.s—. 6. Making the count.--The "peen " call given.by woodcock on the ground should‘be used for counting entirely, if possible, as being more reliable for separating different individuals. The flight song should only be resorted to if it can be definitely distinguished as a separate bird, or if disturbing noises such as frogs make it impossible to hear woodcock ground calls. Once the approximate starting time has been con- firmed the census taker waits at the first stop until a woodcock is de- finitely heard calling on a known' 'singing groun ." Check the time and ‘wait there 2 minutes counting all different birds heard. However, since the first stop may not have a performing bird each evening, a certain amount of discretion must be used. The experienced census taker will know approximately what time his birds will start performing on a given evening. The suggested prOcedure, in case no bird is singing at the first stop, would be to wait 5 minutes after the latest expected commence- ment of song, then drive on to the second stop. Because of this, as well as other unpredictable points, it is almost essential that a census taker receive instruction from.someone experienced with woodcock ground calls and flight songs before starting out "on his own." At the end of 2 minutes proceed as rapidly as possible to the next stop and listen there for 2 minutes, again counting all birds heard. Repeat this procedure over the entire route. If timing is correct (except on very short routes) the evening calling period should.be practically over after the last 2 minutes of listening is completed. l 7. Things to avoid.--Counts should not be made during the period of 2 days before a full moon and one day afterward (4 days in all), as it has been found the birds are very inconsistent in performing then. They should not be made in.heavy rain or snow or when the temperature is below approximately 25 degrees or when a strong wind is blowing. A.win veloci- ty of "Beaufort 3" (8-10 miles per hour, causing leaves and twigs to be in constant motion and light flags to be extended) is too strong. The best results will be obtained on warm, clear, quiet evenings. V. Recording the Census Data A.standard form is provided for recording the pertinent data concern- ing your specific route and counts. ‘For your convenience the attached sample data sheet (filled in) may help clarify the technique. Records should include: Date, weather (points circled on the form) including sky conditions and precipitation if any, temperature, wind, moon' s phase, length of route, intervals between each stop, birds heard at each stop- combining both sides of the road (record 0 if no birds are heard), time of starting, and time of finishing. Space is supplied for recording data on the same route three different nights if it should'be necessary to re- peat the coverage for any reason. All data should be recorded on the forms furnished you. Please describe each area'by definite local geographical boundaries (example: Black.Hill Road, running 2.4 miles south from. the road leading to Brown's gravel pit). This exact description is needed in case of change in observers in subsequent years. It is recommended that a rough sketch made of your census route be drawn on the back of the data sheet unless the boundaries have obvious geographical markers shown on easily available maps. In case stop No. l (the start of the route) does not have a convenient geographical marker it may then be described as being a given number of tenths of a mile and a definite compass direction from a known marker. Indicate whether the route is exactly the same as that covered last year to aid the compiler. VI. Reporting the Census Data At the conclusion of census studies please return your forms directly to your local coordinator. Please make a special effort to meet his dead- line date, otherwise the over-all compilation will be held up and the use- fulness of your efforts impaired. ' Remember this method of obtaining an index of abundance of woodcock is still in the experimental stage and your comments and suggestions will be welcome. 70395 State : ' County: Town or Township: Census route' name or No: WOODCOCK CENSUS COUNT “747 Michigan Year: 1955 ’Q<<\\ - Isabella Observer: Irene F. Jorae Chippewa 2 Observer's Address: W 601 8. Arnold St. Mt. Pleasant, Michigan Same route used lastgyear: Yes Details of Census route: with road running north and south - south 3 miles. - Intersection of M-20, 7 miles east of Mt. Pleasant Number of Birds Recorded 223.99.113.12. 311959212 . 211.99.113.12 pate; h/ZI/SS Date: Date: Time at Start: 8:05 pm Time at Start: Time at Start: H Time at Finish: 8:35 pm Time at Finish: Time at Finish: . (Circle appropriate (Circle appropriate (Circle appropriate :3. item below) item below) item below) Q sky; 1/3 overcast; Sky: clear; 1/3 overcast; Sky: clear; 1/3 overcast; .8 2/3 overcast;overcast 2/3 ovorcast;overcast 2/3 overcast30vercast ‘0 Tampa (De .F.) 20-30; Temp.: (Deg.F.) 20—30; Tsmp.: (Deg.F.) 20-30; a 5 4 Sl-hO; 1-60;61+ 31-1:0;L;1-50;51-60;61+ 31-h0;hl-SO;Sl-60;6l+ 8 «E Wind: calm; ‘ic-ht Wind: calm; light; Wind: calm, light; E}; a) 1 gentle; moderate gentle; moderate gentle; moderate My 33° M0013- 1/4; 1/2; Moon: none; l/h; 1/2; Moon: none; 1/4; 1/2; 93:; ,5: 3m; lull 3/14; full 3/h; full 273 ‘F‘ Pfecipitation:- Precipitation: none; Precipitation: none; ‘ rain; snow rain; snow rain; snow 1 10.0} . O i “”2”"; .1 2’ 0 ”arts“; * 0 i A $333? i l _._ i. j; $1.6) Ti. ESE-2.9} 1 M . .fjguu 2 "52.1 I 0 973.2 0 A 10 i i A ‘11 ‘ 3.. “ a M £3 w A l in. M 1: p 371.}. _. i _ TOTAL 5 70395 PC m 9.2L 8:1” "NM Ni'i’ifl'iiii ’1’.