Reproduction in a Declining Population of Wild Turkeys in Arkansas Author(s): Wayne E. Thogmartin and James E. Johnson Source: The Journal of Wildlife Management , Oct., 1999 , Vol. 63, No. 4 (Oct., 1999), pp. 1281-1290 Published by: Wiley on behalf of the Wildlife Society Stable URL: https://www.jstor.org/stable/3802846 JSTOR is a not-for-profit service that helps scholars, researchers, and students discover, use, and build upon a wide range of content in a trusted digital archive. We use information technology and tools to increase productivity and facilitate new forms of scholarship. For more information about JSTOR, please contact support@jstor.org. Your use of the JSTOR archive indicates your acceptance of the Terms & Conditions of Use, available at https://about.jstor.org/terms Wiley and Wildlife Society are collaborating with JSTOR to digitize, preserve and extend access to The Journal of Wildlife Management This content downloaded from 128.227.118.220 on Sun, 02 Mar 2025 04:19:01 UTC All use subject to https://about.jstor.org/terms J. Wildl. Manage. 63(4):1999 SELENIUM IN PREDATORY BIRDS' Santolo and Yamamoto 1281 Kesterson Reservoir, California. Water, Air and Soil Pollution 74:345-361. WESTCOT, D. W., C. A. ENOS, J. E. CHILCOTT, AND K. K. BELDEN. 1990. Water and sediment quality survey of selected inland saline lakes. California Regional Water Quality Control Board, Central Valley Region, Sacramento, California, USA. WIEMEYER, S. J., AND D. J. HOFFMAN. 1996. Repro- duction in eastern screech-owls fed selenium. Journal of Wildlife Management 60:332-341. YAMAMOTO, J. T., G. M. SANTOLO, AND B. W WIL- SON. 1998. Selenium accumulation in captive American kestrels (Falco sparverius) fed seleno- methionine and naturally incorporated selenium. Environmental Toxicology and Chemistry 17: 2494-2497. ZAR, J. H. 1974. Biostatistical analysis. Prentice-Hall, Englewood Cliffs, New Jersey, USA. Received 26 October 1998. Accepted 18 April 1999. Associate Editor: Rattner. REPRODUCTION IN A DECLINING POPULATION OF WILD TURKEYS IN ARKANSAS WAYNE E. THOGMARTIN,1,2 U.S. Geological Survey, Biological Resources Division, Arkansas Cooperative Fish and Wildl Research Unit, Department of Biological Sciences, University of Arkansas, Fayetteville, AR 72701, USA JAMES E. JOHNSON, U.S. Geological Survey, Biological Resources Division, Arkansas Cooperative Fish and Wildlife Rese Unit, Department of Biological Sciences, University of Arkansas, Fayetteville, AR 72701, USA Abstract: Wild turkey (Meleagris gallopavo) abundance in the Ouachita Mountains of Arkansas has decl since 1987. We studied reproductive output of 106 radiotagged hens from 1993 to 1996 to understand fact likely responsible for this decline. Low rates of initiation of incubation (65% for adult and 53% for subad hens), low nesting success (13%), and small clutch sizes (9.0/adult hen, 7.8/subadult hen) characterized population. Mean hen success was 0.20 for adult hens and 0.10 for subadult hens. Survival of poults (34 2 weeks posthatch) and hens during the breeding season (Kaplan-Meier survival estimates = 74.8% for adul and 79.1% for subadults) was likely not responsible for the population decline. Heavier hens laid larger clut and presumably entered the nesting season in better condition, leading to earlier initiation of incubation greater probability of successful nesting. Hens entering the nesting season in pooi condition reduced clutc size investment or delayed nesting. Management efforts aimed at increasing hen condition prior to nes could produce increases in reproduction. JOURNAL OF WILDLIFE MANAGEMENT 63(4):1281-1290 Key words: Arkansas, hen success, Meleagris gallopavo, nest predation, nesting success, physiological c dition, poult survival, wild turkey. Change in abundance of wild turkeys is large- ly dependent on annual rates of reproduction (Vangilder 1992). In many wild turkey popula- tions, annual fluctuations in abundance may ap- proach +50% of the long-term mean (Mosby 1967, Glazener et al. 1990, Roberts et al. 1995). One factor responsible for these changes in abundance is high annual variation in nesting success (Roberts et al. 1995, Roberts and Porter 1996a). In the Ouachita Mountains of westcentral Ar- kansas, wild turkey harvest declined by 50% be- tween 1987 and 1996, suggesting wild turkey abundance declined in this area (Lint et al. 1995). We hypothesized a prolonged period of low nesting success was responsible for this de- cline. To test this hypothesis, we compared re- production of wild turkeys from the Ouachita Mountains with populations exhibiting increas- ing abundance. We examined age-specific rates of initiation of incubation, nesting success, hen success, clutch size, and breeding phenology. We also tested the hypothesis that breeding sea- son survival for wild turkey hens or poults was responsible for the decline. STUDY AREA Research was conducted on Muddy Creek Wildlife Management Area (Muddy Creek), a 1 Present address: Cooperative Wildlife Research Laboratory and Department of Zoology, Southern Il- linois University, Carbondale, IL 62901, USA. 2 E-mail: wthogma@siu.edu This content downloaded from 128.227.118.220 on Sun, 02 Mar 2025 04:19:01 UTC All use subject to https://about.jstor.org/terms 1282 DECLINE IN WILD TURKEYS * Thogmartin and Johnson J. Wildl. Manage. 63(4):1999 39,000-ha tract within the Ouachita National Forest and cooperatively managed by the U.S. Forest Service and Arkansas Game and Fish Commission. Topography of Muddy Creek was a series of east-west ridges and stream valleys ranging in elevation from 200 to 750 m ( = 331 m). The dominant cover type was shortleaf pine (Pinus echinata), which composed 45% of the study area; mixed pine-hardwood (35%), hardwood (5%), and open areas (primarily pas- ture and clearcuts; 15%) composed the remain- ing habitats. Hardwoods included post oak (Quercus stellata), southern red oak (Q. falca- ta), white oak (Q. alba), mockernut hickory (Carya tomentosa), sweetgum (Liquidambar styraciflua), and blackgum (Nyssa sylvatica). Annual precipitation averaged 139 cm between 1993 and 1996 (range = 105-154 cm), and mean annual temperature was 170C (range = -17-40'C). The freeze-free period annually ranged from 180 to 216 days (National Oceanic and Atmospheric Administration 1992-96). METHODS We used rocket nets (Bailey et al. 1980) to capture wild turkeys between January and March 1993-96. We determined sex and age (adult or subadult) from feathers (Larson and Taber 1980), and body mass to the nearest 0.1 kg. Backpack harnesses (Kurzejeski et al. 1987) rigged with shock cord (Roberts and Porter 1996b) were used to attach 110-g (?:3% of body mass) radiotransmitters (Telonics, Mesa, Arizo- na, USA). Radiotransmitters were equipped with a 4-hr delay motion switch (Roberts et al. 1995). Individually numbered aluminum leg bands were attached to the left leg of each cap- tured bird; all birds were released at their cap- ture sites. We located wild turkeys for up to 30 months, until the bird died, or batteries failed. Hens were located by triangulation at least ev- ery fourth day during the nesting season (15 Mar-early Aug), and often every 1-2 days when localized movement by hens suggested possible egg laying. Monitoring for activity signals oc- curred daily during egg-laying and incubation periods. We designated a nest to be in incubation when a hen remained at the same location for 2 consecutive days of radio contact or a consis- tent inactive or mortality signal was received (Miller et al. 1998). Incubation differed from nesting attempt in that attempts ending in fail- ure during the egg-laying period were not in- cluded. Because of the high rate of predation in this area (Moore 1995), we located nests as soon as possible after initiation of incubation. To prevent disturbance to incubating hens, nests were typically flagged 3 or 4 days into in- cubation at distances -30 m from the nest site. We monitored incubating hens daily until in- creased activity or movements indicated they had left the nest area. Nest sites were then lo- cated, and number of eggs laid and number of eggs hatched were recorded. We classified nests as successful if -1 egg hatched (e.g., eggshell membrane partially separated from the eggshell and small eggshell cap separated from the larg- er eggshell bottom). Unsuccessful nests were categorized as abandoned if unhatched eggs re- mained, or preyed upon if nest or eggs exhib- ited obvious signs of disturbance or destruction. We estimated clutch size by counting recon- structed egg fragments in unsuccessful nests and egg caps in successful nests. This estimate provided a minimum number of eggs because predators may have removed some eggs. Num- ber of days a nest survived was calculated by subtracting estimated beginning incubation date from date of known nest fate. We defined incubation rate as the percentage of radiomarked hens ultimately initiating incu- bation among those in the sample 2 weeks prior to the earliest known nesting attempt. Adult and subadult hens were analyzed separately due to expected differences in nesting success and clutch size (Vangilder 1992). First incubation at- tempts were separated from subsequent at- tempts. If the first incubation attempt of a hen was unsuccessful and she survived >30 days af- ter initial nest failure, she was considered avail- able for second nesting. We defined hen success as the proportion of nesting hens ultimately hatching -1 egg, regardless of the number of nesting attempts (Vangilder 1992). Hens not at- tempting to nest were not included in this cal- culation. We assumed initial brood size equaled the estimated number of hatched eggs. From 1993 to 1995, hens successfully producing a clutch of poults were flushed at 2 and 4 weeks posthatch to determine number of surviving poults. In 1996, we determined the number of surviving poults by attracting radiotagged hens into open areas with recorded lost poult calls and then counting the number of poults (Kimmel and Tzilkowski 1986). A poult survival ratio was cal- culated by comparing the proportion of surviv- This content downloaded from 128.227.118.220 on Sun, 02 Mar 2025 04:19:01 UTC All use subject to https://about.jstor.org/terms J. Wildl. Manage. 63(4):1999 DECLINE IN WILD TURKEYS * Thogmartin and Johnson 1283 Table 1. Hen wild turkey nesting parameters for Muddy Creek Wildlife Management Area, Arkansas, 1993-96. Third attempts are not included; subadults did not attempt >2 nests/season. Four of 22 adult hens attempted third nests; none were successful. A = adult; S = subadult; n = number of hens with radios, including newly captured birds and birds from previous years. Available Incubation 1st nest to renest Renest 2nd nest Hen Natality Total Age Year n rate (n) success (n) (n) rate (ni) success (n) successa rateb productivity, A 1993 30 0.434 (13) 0.000 (0) 13 0.308 (4) 0.000 (0) 0.000 0.000 0.00 S 15 0.333 (5) 0.000 (0) 5 0.000 (1) 0.000 0.000 0.00 A 1994 34 0.676 (23) 0.174 (4) 19 0.368 (7) 0.000 (0) 0.174 0.477 1.05 S 3 0.667 (2) 0.000 (0) 2 0.000 (0) 0.000 0.000 0.00 A 1995 27 0.667 (18) 0.333 (6) 12 0.583 (7) 0.143 (1) 0.389 1.020 2.57 S 15 0.867 (13) 0.154 (2) 10 0.000 (5) 0.154 0.457 1.11 A 1996 27 0.852 (23) 0.174 (4) 19 0.211 (4) 0.000 (0) 0.174 0.560 1.15 S 5 0.000 (0) 0.000 0.000 0.00 A Total 118 0.653 (77) 0.182 (14) 63 0.349 (22) 0.045 (1) 0.195 0.504 1.15 S 38 0.526(20) 0.100 (2) 17 0.353 (6) 0.000(0) 0.100 0.180 0.41 Overall 156 0.622 (97) 0.165 (16) 80 0.350 (28) 0.036 (1) 0.109 0.423 0.96 a Probability a nesting hen will have 1 successful nest in 1 or more attempts (Vangilder et al. 1987). b Natality rate was calculated as a function of nesting rate, clutch size, nesting success, and hatchability (Vander Haegen for details. C Productivity was measured as the number of successful nests divided by the number of monitored hens (including no mean clutch size (Miller et al. 1995). ing poults at 2 and 4 weeks posthatch to num- ber of eggs hatched. Age-specific hen natality rates (mx) were calculated as mx = [(nrx)(cx)(nsx)(hsx)]/2, where nir = nesting rate; cx = clutch size; nsx = nesting success; and hsx = hatchability (Van- der Haegen et al. 1988). We calculated breeding season survival for the period 16 March to 15 August, which cor- responded to hen dispersal, spring gobbler hunting, nesting, and brood rearing (4 weeks posthatch). Survival rates were estimated using the Kaplan-Meier product limit method modi- fied for staggered entry (Pollock et al. 1989). Censoring decisions were based on recommen- dations of Vangilder and Sheriff (1990). The marked sample each year included hens surviv- ing from previous years, and thus were not in- dependent samples. Subadult hens surviving to their second winter were reclassified as adults. Table 2. Mean annual body mass (kg) of all captured hen wild turkeys in Muddy Creek Wildlife Management Area, Arkansas, 1993-96. Adult Subadult Year SE n SE n 1993 4.47Aa 0.09 42 4.15A 0.16 19 1994 4.38A 0.12 32 3.60A,B 0.24 5 1995 4.48A 0.23 24 3.58B 0.11 16 1996 4.28A 0.08 9 3.26B 0.07 9 Total 4.43 0.07 107 3.74 0.09 49 3 Means sharing the same letter did not differ (Tukey-Kramer HSD, P > 0.05). We used chi-square, Fisher's exact test, and analysis of variance to examine differences in reproductive parameters based upon age class, study year, nest attempt, and nest fate. Contin- uous variables were evaluated for normality with the Shapiro-Wilk test, and heteroscedastic- ity of variances with Bartlett's and O'Brien's tests (Zar 1984). Residual plots from least- squares regressions were examined to identify outliers and nonnormality. Some variables (e.g., body mass) were nonnormal and required com- mon logarithm transformations. We used logis- tic regression to identify factors affecting nest fate. Statistical analyses were conducted with JMP 3.2.1 (SAS Institute 1995), with a Type I error of a = 0.05. All means are reported +1 standard error. RESULTS In 4 years of study, 148 hen wild turkeys were captured, 129 were outfitted with radiotrans- mitters, and 106 were monitored during nest- ing. We monitored 58 hens (55%) for 1 nesting season, 46 (43%) for 2 nesting seasons, and 2 (2%) for 3 nesting seasons; 23 hens either died before the reproductive period or were not monitored with sufficient frequency to deter- mine nesting status. Summed over 4 years, 156 hens were available for nesting (Table 1). Adult hens were heavier (4.43 ? 0.07 kg) than subadult hens (3.74 ? 0.09; t154 = 6.11, P < 0.001; Table 2). Mass of adult hens was mark- edly stable over the study (H = 4.33, P = 0.23), while subadult mean mass declined 21.5% over This content downloaded from 128.227.118.220 on Sun, 02 Mar 2025 04:19:01 UTC All use subject to https://about.jstor.org/terms 1284 DECLINE IN WILD TURKEYS * Thogmartin and Johnson J. Wildl. Manage. 63(4):1999 >_4 24 May 1993 4 U 2I L1 102 116 130 144 158 172 73 May Q 6- 1994 z 6 4 5 M 2- U 11 07 95 109 123 137 151 165 179 Z 6- 5- 4- 10 May Us 1996 0 z LU 4 Ul 2 U1 95 109 123 137 151 165 179 DAY OF YEAR Fig. 1. Day of year adult wild turkey hens initiated incubation of first nests at Muddy Creek Wildlife Management Area, Ar- kansas, 1993-96. Date shown is mode of annual initiation of incubation. the 4 years (H = 13.58, P = 0.004). During the early spring of 1995, mass of adult and subadult hens increased with capture date (F1,15 = 13.89, adjusted R2 = 0.46, P = 0.002, n = 16). Individual productivity reflected hen mass. In 1995 and 1996, the 4 heaviest adult hens (-22 SE from the annual mean) attempted to nest in 5 out of 8 possible nest-years, while none of the 4 lightest adult hens (-2 SE from the annual mean) attempted nesting. One of the lightest hens died during her first nesting season, and the 3 others were dead before the next nesting season. Table 3. Annual and total mean clutch size of adult and sub- adult wild turkeys from Muddy Creek Wildlife Management Area, Arkansas, 1993-96. Clutch size estimates were not available for all nests in all years. Mean clutch size for nests that hatched (successful nests) is provided. Adult Subadult x SE n I SE n 1993 10.25 0.95 4 6.67 1.67 3 1994 8.91 0.86 11 1995 9.92 0.66 13 8.30 0.98 5 1996 7.75 0.79 12 Total 9.03 0.42 40 7.75 0.86 8 Successful nests 8.43 0.88 15 8.00 2 Mean nest participation age classes (Fisher's exa was different between yea lihood ratio G = 11.5, P did not nest in 1996. Seve hens (65%) and 20 of 38 initiated incubation, yi (62%) incubating a first n Incubation of first nests was lowest in 1993 (40%) and highest in 1995 (74%). Twenty-two of 63 adult hens (35%) and 6 of 17 subadult hens (35%) available for second nesting at- tempts initiated incubation. None of the sub- adult hens (n = 6) and only 4 of 22 adult hens (18%) began incubation of third clutches. Nesting Chronology Chronology of nesting varied considerably over the 4-year study period. Hens began first- nest incubation earliest in 1995 (11 Apr) and latest in 1993 (30 Apr; Fig. 1). Median annual date of first-nest incubation for adult hens ranged from 26 April in 1995 to 20 May in 1993. Latest dates for first-nest incubation ranged from 10 May in 1995 to 21 June in 1996. The overall mean commencement date for in- cubation was 7 May, while the median date in- cubation began was 3 May. Clutch Size A total of 136 eggs hatched over the 4-year study (Table 3). For nests of known clutch size (n = 15), egg hatchability was 97.7%. Mean clutch size of adult hens was 9.0 ? 0.4 eggs/ nest (n = 40), and 7.8 ? 0.9 eggs/nest (n = 8) for subadult hens. The smallest successful clutch contained 5 eggs, and the largest 15 eggs. Four clutches of <5 eggs were observed, but these clutches were believed incomplete due to This content downloaded from 128.227.118.220 on Sun, 02 Mar 2025 04:19:01 UTC All use subject to https://about.jstor.org/terms J. Wildl. Manage. 63(4):1999 DECLINE IN WILD TURKEYS * Thogmartin and Johnson 1285 log (CLUTCH SIZE) = 0.54 + 0.66 log (BODY MASS) 1.2- 0o 1.1 o.- o 00 0 , N 1.0 ooo000 o- 0. o0 9. S0.9- 0 ..-o Jo .' o o0 0 0 '0.8- F1,28 = 4.72 0.7- o 0 o Adjusted R2 = 0.117 n = 29 P= 0.039 0.6-1 1 1 0.45 0.50 0.55 0.60 0.65 0.70 0.75 0.80 log (BODY MASS) Fig. 2. Least-squares regression (and 95% CL) of common logarithms of clutch size against hen body mass, Muddy Creek Wildlife Management Area, Arkansas, 1993-96. -J 75- 50- C/) 25- 100 120 140 160 DAY OF YEAR Fig. 3. Nest survival of wild turkeys at Muddy Creek Wildlife Management Area, 1993-96, as a logistic function of day of year incubation began (DIB) for all nesting attempts with com- plete information (n = 53). partial egg predation and were therefore ex- cluded. Clutch size did not differ between adults and subadults (t48 = 0.86, P = 0.39) or between study years for adults (F3,3s = 1.13, P = 0.35) or subadults (X21 = 1.16, P = 0.28). Clutch size was positively related to the loga- rithm of hen body mass (F1,27 = 4.72, adjusted R2 = 0.117, P = 0.04, n = 29; Fig. 2). Nest Survival and Predation During the study, 17 of 129 nesting attempts reaching incubation (13%; both age classes and all attempts) successfully hatched poults (Table 1). Annual first-nest success varied from com- plete failure in 1993 to 26% success in 1995. Successful clutches were incubated 27.6 ? 0.4 days. Mean number of days a nest survived was 16.3 ? 0.9 days. The number of days a first-nest survived did not differ between study years (F3,93 = 0.11, P = 0.95). Half of all nests were preyed upon within 12 days of initiation of in- cubation, and only 5 of 57 failed nests survived beyond 24 days. There were 97 first nesting attempts of which 16 were successful (17%). Date incubation be- gan was a significant predictor of successful nesting (log-likelihood X21 = 9.81, n = 53, P = 0.0017, 87.7% correct classification; Fig. 3). Probability of successful incubation = e[12.46 - 0.12xDIB]/(l + e12.46 - 0.12xDIB]), where DIB equals the date incubation began. Successful nests were initiated and incubation began earlier (f = 22 Apr ? 5.0 days) than failed nests (I = 7 May ? 2.1 days). Number of days invested in first-nest incubation did not affect probability of renesting (logistic regres- sion X21 = 2.42, P = 0.12), but the earlier a hen initiated a first nest ending in failure, the more likely she was to attempt a second nest (logistic regression X21 = 5.03, P = 0.03). In 1995, the year of earliest mean nest initiation, 1 adult hen initiated incubation of a second nest after loss of her >2-week-old brood; this nest ended in failure. Only 1 of 32 second and third nesting attempts was successful (3%). Fifteen of 77 adult hens (19%) and 2 of 20 (10%) subadult hens that attempted nesting were successful. Although hen age was not an important determinant of overall nesting suc- cess (Fisher's exact test: P = 0.51), there were age-related differences in reproduction. Three adult hens were responsible for 35% of all suc- cessful nests over the 4-year study. Mean adult hen success, a measure of individual fitness over the breeding season, was twice that of subadult hens (19.5 vs. 10.0%; Table 1). Subadult hens nested successfully only in 1995, and thus failed to produce poults in 3 of 4 years. Adult hens produced poults in 3 of 4 years, with nesting success ranging from 0.00 in 1993 to 0.39 in 1995. Clutch size and the date of initiation of in- cubation for initial nests and the interaction be- tween these 2 factors were related to probability This content downloaded from 128.227.118.220 on Sun, 02 Mar 2025 04:19:01 UTC All use subject to https://about.jstor.org/terms 1286 DECLINE IN WILD TURKEYS * Thogmartin and Johnson J. Wildl. Manage. 63(4):1999 Table 4. Logistic regression of nest fate of wild turkeys from Muddy Creek, Arkansas, 1993-96, as a function of clutch size and day of year incubation began (DIB) for first-nest attempts (n = 46). Nests were correctly classified 67% of the time. Term Estimate Lower 95% Upper 95% SE X2 P Intercept -47.67 -92.50 -12.49 20.02 5.67 0.017 Clutch 6.35 2.01 12.14 2.55 6.19 0.013 DIB 0.39 0.10 0.76 0.17 5.60 0.018 DIB x clutch -0.05 -0.10 -0.02 0.02 6.19 0.013 Whole model 12.02 0.007 of nesting success (Tab size and earlier initiati tempts or, conversely, and delays in incubati greater nesting success In all, 76% of nest failu nest predation; an addi ures resulted from mor prior to completion of tics of the nest site an gested important pred coons (Procyon lotor) a phe obsoleta obsoleta; Goetz 1980). Survival In 4 years, 136 poults hens (: = 8.5 poults/suc of 17 successful nest sites was too disturbed to determine number of poults produced. Thir- teen adult hens produced 111 poults during first nesting attempts (f = 8.5 poults/hen), 9 poults INITIATION DATE Early Late CZ -J Large Clutch + Large Clutch + Early Initiation of Later Initiation of Incubation = Incubation = High Nesting Low Nesting Success Success _N -I- I- F_ o Small Clutch + Small Clutch + Early Initiation of Later Initiation of Incubation = Incubation = Low Nesting High Nesting Success Success E Fig. 4. Effect of the interaction of clutch size and date incu- bation was initiated on initial nesting success of wild turkeys at Muddy Creek Wildlife Management Area, Arkansas, 1993- 96. were hatched from a single adult hen during a second nesting attempt, and 16 poults were hatched by 2 subadult hens during their first nesting attempt. After 2 weeks, a mean of 2.7 poults survived per adult hen (n = 14 broods; survival rate = 0.319), and 3.0 poults survived per subadult hen (n = 2 broods; survival rate = 0.375). No poults from the successful second nest attempt (n = 9) survived to 2 weeks post- hatch. When surviving broods were examined, as opposed to surviving poults, 5 of 13 broods were lost by 2 weeks posthatch (survival rate = 0.615). After 4 weeks, mean brood size was es- timated as 2.0 young/adult hen (survival rate = 0.234) and 3.0 young/subadult hen (survival rate = 0.375); however, 4-week posthatch estimates may have been confounded by flocking of mul- tiple wild turkey hens and their poults. Hen survival during the March to August breeding season averaged 0.75 ? 0.4 for adults (range = 0.63-0.90, n = 135) and 0.79 ? 0.6 for subadults (n = 43). No survival differences were observed between age classes (log-rank X21 = 0.23, P = 0.63), nesting and nonnesting hens (log-rank X21 = 0.17, P = 0.68), or years for subadults (log-rank X23 = 4.94, P = 0.18), but a difference was observed between years for adults (log-rank X23 = 9.97, P = 0.02). Adult hen survival was 24% greater in 1993 and 1996 (>0.87) than 1994 and 1995 (<0.66). DISCUSSION During the period of study, low rates of ini- tiation of incubation, small clutch size, and low nesting success characterized the Muddy Creek population of wild turkeys. Conversely, poult survival in Muddy Creek was similar to other wild turkey populations (e.g., Glidden and Aus- tin 1975, Speake 1980, Seiss 1989). Hen surviv- al during the breeding season (0.75 ? 0.4) also was similar to other populations of female wild turkeys (e.g., Bidwell and Maughan 1988). In populations described as stationary or increas- ing, hen survival averaged 0.72 ? 0.03 during This content downloaded from 128.227.118.220 on Sun, 02 Mar 2025 04:19:01 UTC All use subject to https://about.jstor.org/terms J. Wildl. Manage. 63(4):1999 DECLINE IN WILD TURKEYS e Thogmartin and Johnson 1287 the recruitment period in Wisconsin (16 Mar- 14 Jul; Wright et al. 1996), 0.78-0.84 during spring in 3 study areas in Missouri (15 Mar-31 May; Vangilder and Kurzejeski 1995, Vangilder 1996), and 0.80 ? 0.3 during spring in New York (22 Feb-31 May; Roberts et al. 1995). Giv- en similar breeding season survival rates, typical poult survival, and negligible legal and illegal harvest outside of the breeding season (J. E. Johnson, unpublished data), our data suggested low reproductive output was responsible for the observed decline of wild turkeys in the Ouachi- ta Mountains. Participation in incubation by wild turkeys in Muddy Creek (62%) was low when compared to studies using similar methodology to calcu- late incubation rates. Badyaev et al. (1996), for instance, found nest incubation rates of 0.83- 0.93 for wild turkey hens in the Ozark High- lands of Arkansas. Palmer et al. (1993) and Mill- er et al. (1998) reported a mean nest incubation rate of 0.72 and 0.73, respectively, for a declin- ing population in Mississippi. Only Miller et al. (1995) reported a similar incubation rate (63%). Numerous studies have reported a mean ini- tial wild turkey nesting success of <:0.50 (e.g., Speake 1980, Palmer et al. 1993, Nicholson et al. 1995, Vangilder and Kurzejeski 1995, Bad- yaev et al. 1996, Miller et al. 1998), but only Paisley et al. (1998) reported nesting success as low as was observed in this study (17%). For declining populations, both Miller et al. (1998) and Paisley et al. (1998) reported hen success of <0.30, which was similar to hen success ob- served in Muddy Creek. Some radiotagged hens in Muddy Creek like- ly initiated egg laying, but hens or nests were preyed upon or abandoned prior to start of in- cubation. Nests lost early were not located prior to failure, which biased our estimates of pro- ductivity. To offset this potential bias, we cal- culated natality rate as described by Vander Haegen et al. (1988). This index incorporated nesting participation, clutch size, and nesting success into a single measure of reproductive performance (Table 1). Natality rate at Muddy Creek ranged from 0.00 to 1.02, with a mean of 0.50 for adults and 0.18 for subadults. Vander Haegen et al. (1988) reported natality rates of 3.30 for adults and 1.45 for subadults, values substantially higher than observed in this study. Particularly influential in this index was the low observed clutch size. Mean clutch size of adult hens in the Muddy Creek population (9.0 eggs/clutch) was among the lowest reported for eastern wild turkeys. Vangilder (1992) reviewed 7 studies of wild tur- keys and suggested hens typically lay a clutch of 10-13 eggs. Miller et al. (1995) reported mean clutch sizes of 8.5 and 9.4 eggs/nest for 2 studies in Mississippi. In the Ozark Mountains of Arkansas, Badyaev et al. (1996) reported a mean clutch size of 10.8 eggs/nest from both subadult and adult hens. Low reproductive parameters such as initia- tion of nesting and clutch size likely have a physiological basis (Rowe et al. 1994, Miller et al. 1995). Low body mass prior to egg laying may result in delayed nest initiation or in a hen foregoing nesting (Rowe et al. 1994, Vangilder and Kurzejeski 1995, Miller 1997). Porter et al. (1983) suggested a threshold body mass may ex- ist, below which a hen cannot initiate nesting. In Muddy Creek, adult hen body mass (annual i = 4.3-4.5 kg) was similar to capture mass in other regions (e.g., 4.4 kg in Massachusetts [Vander Haegen et al. 1988]; 4.5-4.9 kg in Mis- souri [Vangilder and Kurzejeski 1995]; 4.1 dur- ing normal years in Mississippi [Miller 1997]). However, low productivity of pine forests in the Ouachita Mountains (Wigley et al. 1986, Bid- well et al. 1989) may have important conse- quences for hens building lipid reserves prior to onset of nesting (Drent and Daan 1980). Pro- duction of lipid reserves may have been espe- cially difficult given substandard precipitation in February and March in every year of the study (departure from 30-yr mean = -5.0 ? 2.1 cm; Thogmartin 1998). We suggest the high rate of nest predation in Muddy Creek may be due, in part, to a behav- ioral response by hens with reduced endoge- nous reserves during incubation. Body mass has been related to reproductive success in several galliforms (e.g., ruffed grouse [Bonasa umbel- lus] Beckerton and Middleton 1982; Scottish ptarmigan [Lagopus mutus] Moss and Watson 1984; northern bobwhite [Colinus virginianus] Guiliano et al. 1996; scaled quail [Callipepla squamata] Guiliano et al. 1996), including wild turkeys (Porter et al. 1983). During incubation, hens with low lipid reserves may have increased the frequency and duration of foraging trips from the nest (Hogan 1989). Reed et al. (1995) found incubating greater snow geese (Anser ca- erulescens atlanticus) adjusted feeding sched- ules to compensate for low body mass. This strategy has been dubbed the "risky" strategy This content downloaded from 128.227.118.220 on Sun, 02 Mar 2025 04:19:01 UTC All use subject to https://about.jstor.org/terms 1288 DECLINE IN WILD TURKEYS * Thogmartin and Johnson J. Wildl. Manage. 63(4):1999 by Ankney and Alisauskas (1991). Birds increas- ing trips from the nest increase risk of predation to the nest and themselves. This risk may be especially acute in years and areas in which predators are abundant, which occurred in ev- ery year of our study (Thogmartin 1998). The influence on initial nest fate by clutch size, date incubation began, and their interac- tion suggests a constraint to hens increasing clutch size, primarily in the form of delayed in- cubation (Table 4). Probability of nest loss de- creased with increases in clutch size or com- mencement date of first nests, but not with in- creases in both measures simultaneously. This result may be because hens able to nest early and those laying larger first clutches later were in better physiological condition and therefore capable of maintaining greater incubation con- stancy. While early nesting led to an overall greater probability of nesting success, as evi- denced by Figure 3, interaction of the day in- cubation began and first-nest clutch size pre- sented 2 alternative strategies for hens entering the nesting season. A hen in good condition may have been able to increase her energetic commitment to clutch size when nesting early, whereas a hen in poor condition might delay initiation of nesting until her endogenous re- serves were of sufficient size to allow her to be- gin nesting, but at the cost of a smaller clutch. Later first-nesting attempts were less successful, but later-nesting hens that expended less en- dogenous reserves on egg formation and thus produced smaller clutches performed better than later-nesting hens with larger clutches (Fig. 4). This interaction may explain previous failures to find a relation between first-nest clutch size and nesting chronology (e.g., Van- gilder and Kurzejeski 1995). MANAGEMENT IMPLICATIONS Hens in poor condition entering the nesting season were more prone to nest failure. Hence, efforts aimed at increasing hen condition prior to nesting would likely result in favorable in- creases in nesting participation, clutch size, and nesting success. Because habitat diversity influ- ences forage abundance and quality, hens able to access a wide variety of habitats may be able to increase their physiological condition prior to nesting (Miller et al. 1995). One mechanism to increase habitat diversity in a heavily harvested pine forest may be prescribed burning of the understory (Caine et al. 1998). Masters et al. (1996) suggested that prescribed burning on a 3-year rotation increased diversity of available white-tailed deer (Odocoileus virginianus) for- age in the Ouachita Mountains. Hodgkins (1958) reported increased herbaceous growth after fire events in southern pine forests. However, the proximate limitation to suc- cessful reproduction in Muddy Creek was not physiological condition, but was instead preda- tion of nests and poults. Given high predator abundance in the Ouachita Mountains (Thog- martin 1998), habitat management alone is un- likely to solve the problem of declining popu- lation size in wild turkeys. The influence of in- creased hen condition will most likely be evi- dent in years of low or moderate predator density or in years in which alternate prey den- sity is high. ACKNOWLEDGMENTS Financial support for this project was provid- ed by Arkansas Game and Fish Commission, Arkansas Cooperative Fish and Wildlife Re- search Unit, and national, state, and local chap- ters of the National Wild Turkey Federation. Field assistance was provided by R. Chastain, C. C. Ciriano, M. Baron, J. Faibisch, D. Goad, J. H. Herner-Thogmartin, B. Infield, J. Jones, G. Mathis, L. A. Moore, M. C. Rodrigues, and B. A. Schaeffer. This manuscript was improved substantially by comments from S. J. Beaupre, J. L. Roseberry, K. G. Smith, W F. Porter, and an anonymous reviewer. M. R. Widner and D. Urbston commented on an early treatment of these data. This paper is a contribution of the Arkansas Cooperative Fish and Wildlife Re- search Unit-U.S. Geological Survey, Biological Resources Division; Arkansas Game and Fish Commission; University of Arkansas; and Wild- life Management Institute cooperating. LITERATURE CITED ANKNEY, C. D., AND R. T. ALISAUSKAS. 1991. Nutri- ent-reserve dynamics and diet of breeding female gadwalls. Condor 93:799-810. BADYAEV, A. V., T. E. MARTIN, AND W. J. ETGES. 1996. Habitat sampling and habitat selection by female wild turkeys: ecological correlates and re- productive consequences. Auk 113:636-646. BAILEY, W., D. BENNETT, JR., H. GORE, J. PACK, R. SIMPSON, AND G. WRIGHT. 1980. Basic consid- erations and general recommendations for trap- ping the wild turkey. Proceedings of the National Wild Turkey Symposium 4:10-23. BECKERTON, P. R., AND A. L. A. MIDDLETON. 1982. Effects of dietary protein levels on ruffed grouse This content downloaded from 128.227.118.220 on Sun, 02 Mar 2025 04:19:01 UTC All use subject to https://about.jstor.org/terms J. Wildl. Manage. 63(4):1999 DECLINE IN WILD TURKEYS * Thogmartin and Johnson 1289 reproduction. Journal of Wildlife Management 46:569-579. BIDWELL, T. G, AND O. E. MAUGHAN. 1988. Wild turkey survival in southeastern Oklahoma. Pro- ceedings of the Oklahoma Academy of Science 68:59-61. , S. D. SHALAWAY, O. E. MAUGHAN, AND L. G. TALENT. 1989. Habitat use by female eastern wild turkeys in southeastern Oklahoma. Journal of Wildlife Management 53:34-39. CAINE, M. D., T. B. WIGLEY, AND D. J. REED. 1998. Prescribed fire effects on structure in uneven- aged stands of loblolly and shortleaf pines. Wild- life Society Bulletin 26:209-218. DAVIS, J. R. 1959. A preliminary report on nest pre- dation as a limiting factor in wild turkey popula- tions. Proceedings of the National Wild Turkey Symposium 1:138-145. DRENT, R. H., AND S. DAAN. 1980. The prudent par- ent: energetic adjustment in avian breeding. Ar- dea 68:225-252. GLAZENER, W C., D. RANSOM, JR., J. R. CARY, AND O. J. RONGSTAD. 1990. Demographic analysis of a Rio Grande turkey population. Southwestern Naturalist 35:23-27. GLIDDEN, J. W, AND D. E. AUSTIN. 1975. Natality and mortality of wild turkey poults in southwest- ern New York. Proceedings of the National Wild Turkey Symposium 3:48-54. GUILIANO, W. M., R. S. LUTZ, AND R. PATIrO. 1996. Reproductive responses of adult female northern bobwhite and scaled quail to nutritional stress. Journal of Wildlife Management 60:302-309. HODGKINS, E. J. 1958. Effects of fire on undergrowth vegetation in upland southern pine forests. Ecol- ogy 39:36-46. HOGAN, J. A. 1989. The interaction of incubation and feeding in broody junglefowl hens. Animal Be- haviour 38:121-128. KIMMEL, V. L., AND W. M. TZILKOWSKI. 1986. East- ern wild turkey responses to a tape-recorded chick call. Wildlife Society Bulletin 14:55-59. KURZEJESKI, E. W, L. D. VANGILDER, AND J. B. LEWIS. 1987. Survival of wild turkey hens in north Missouri. Journal of Wildlife Management 51:188-193. LARSON, J. S., AND R. D. TABER. 1980. Criteria of sex and age. Pages 190-197 in S. D. Schemnitz, ed- itor. Wildlife management techniques manual. The Wildlife Society, Washington, D.C., USA. LINT, J. R., B. D. LEOPOLD, AND G. A. HURST. 1995. Comparison of abundance indexes and popula- tion estimates for wild turkey gobblers. Wildlife Society Bulletin 23:164-168. MASTERS, R. E., C. W. WILSON, G. A. BUKENHOFER, AND M. E. PAYTON. 1996. Effects of pine-grass- land restoration for red-cockaded woodpeckers on white-tailed deer forage production. Wildlife Society Bulletin 24:77-84. MILLER, D. A. 1997. Habitat relationships and de- mographic parameters of an eastern wild turkey population in central Mississippi. Dissertation, Mississippi State University, Mississippi State, Mississippi, USA. -, B. D. LEOPOLD, AND G. A. HURST. 1998. Reproductive characteristics of a wild turkey pop- ulation in central Mississippi. Journal of Wildlife Management 62:903-910. - , M. WEINSTEIN, S. R. PRIEST, B. D. LEO- POLD, AND G. A. HURST. 1995. Wild turkey re- productive parameters from two different forest ecosystems in central Mississippi. Proceedings of the Annual Conference of the Southeastern As- sociation of Fish and Wildlife Agencies 49:466- 475. MOORE, L. A. 1995. Factors influencing reproductive success of wild turkeys (Meleagris gallopavo) in the Ouachita Mountains of Arkansas. Thesis, Uni- versity of Arkansas, Fayetteville, Arkansas, USA. MOSBY, H. S. 1967. Population dynamics. Pages 113- 136 in O. H. Hewitt, editor. The wild turkey and its management. The Wildlife Society, Washing- ton, D.C., USA. Moss, R., AND A. WATSON. 1984. Maternal nutrition, egg quality and breeding success of Scottish ptar- migan Lagopus mutus. Ibis 126:212-220. NATIONAL OCEANIC AND ATMOSPHERIC ADMINIS- TRATION. 1992-96. Weather data for westcentral Arkansas. National Climatic Data Center, Ashe- ville, North Carolina, USA. NICHOLSON, D. S., M. D. STEWART, R. L. LOCH- MILLER, D. M. LESLIE, JR., R. E. MASTERS, AND T. G. BIDWELL. 1995. Factors influencing eastern wild turkey nesting success. Oklahoma Depart- ment of Wildlife Conservation, Federal Aid in Wildlife Restoration Project W-145-R-1, Progr