Received: 7 January 2022 | Accepted: 24 January 2022 DOI: 10.1002/wsb.1284 P O P U L A T I O N D Y N A M I C S Hunting and environmental influences on survival of male wild turkeys in Virginia and West Virginia Gary W. Norman 1 | Daniel Crawford 2 | Christopher W. Ryan 3 | William K. Igo 4 | Michael J. Cherry 2 1 Virginia Department of Wildlife Resources, P.O. Box 996, Verona, VA 24482, USA 2 Department of Fish and Wildlife Conservation, Cheatham Hall, Virginia Tech, Blacksburg, VA 24061, USA 3 West Virginia Division of Natural Resources, 1145 Evansdale Drive, Morgantown, WV 26506, USA 4 West Virginia Division of Natural Resources, PO Box 67, Elkins, WV 26241, USA Correspondence Gary W. Norman, 103 Comforter Lane, Clear Brook, VA 22624, USA. Email:garyandkimnorman@gmail.com Present address Gary W. Norman, 103 Comforter Lane, Clear Brook, VA 22624, USA. Daniel Crawford, The Jones Center at Ichauway, 3988 Jones Center Drive, Newton, GA 39870, USA. William K. Igo, Rt. 2, Box 79A, Ronceverte, 24970WV, USA. Michael J. Cherry, Caesar Kleberg Wildlife Research Institute, Department of Rangeland and Wildlife Management, Texas A&M, Howe Agricultural Bldg, #20, Kingsville, TX 78363, USA. Funding information West Virgnia Division of Natural Resources, Grant/Award Number: Pittman ‐ Robertson Federal Aid in Wildlife Restoration Act; Virginia Department of Wildlife Resources, Grant/Award Number: Pittman ‐ Robertson Federal Aid in Wildlife Restoration Act Abstract Knowledge of the effects of hunting and environmental influences on survival of eastern wild turkeys ( Meleagris gallopavo silvestris ) is critical to managers setting fall and spring hunting seasons. Research has shown improper season frame- works can result in unsustainably high harvest rates of adult males, affect male age structure, and result in lower hunter satisfaction. Our objectives were to estimate survival rates of males, identify causes of mortality, and relate hunting and environmental influences to male turkey survival. We captured and radio ‐ tagged male wild turkeys in Virginia ( n = 204) and West Virginia ( n = 197), USA, during 2004 – 2007. We used staggered entry Kaplan ‐ Meier models to estimate survival and Cox Proportional Hazards Models to estimate effects of predictor variables on survival. Survival was estimated for 3 distinct periods of interest: annual, fall hunting (October – Jan- uary), and spring hunting (April – May). The leading causes of mortalities (209 turkeys) were legal spring harvest (42%), predation (25%), and poaching (17%). Only 8 turkeys (4%) were taken during fall hunting seasons. Confidence intervals for annual survival of 2 year ‐ old and 3+ year ‐ old turkeys over- lapped; therefore, we combined adult ages into a single category (2+). Adult (2+) annual survival was 0.63 (95% CI = 0.58 – 0.69) and the harvest rate was 25% (95% CI = 20 – 29%) for the combined states. Annual survival rates for adults (2+) were greater than in most other published studies, whereas adult (2+) spring harvest rates were lower. For juvenile males, annual Wildlife Society Bulletin 2022;46:e1284. wileyonlinelibrary.com/journal/wsb © 2022 The Wildlife Society | 1 of 17 https://doi.org/10.1002/wsb.1284 survival was 0.74 (95% CI = 0.68 – 0.79) and spring harvest rate was 7% (95% CI = 3 – 11%). High juvenile and adult (2+) survival may have been related to low harvest rates. Adult turkeys (2+) had 46% greater risk of dying than one ‐ year ‐ old birds and were 3.7 times more likely to be harvested than juveniles. Age, a relative phenology index (RPI; spring green ‐ up), and white oak ( Quercus alba ) acorn production were included in the top models for annual survival, spring season survival, and spring harvest risk. Increasing RPI (more foliage) decreased mortality risk and greater white oak ( Quercus alba ) acorn abundance increased mortality risk. Across 4 regions in the 2 states, fall survival was high (0.90, 95% CI = 0.87 – 0.93). The impact of fall hunting on males in Virginia was low (5% harvest rate, 95% CI = 0 – 9%). Overall, spring harvest had the greatest effect on male survival, although those effects were moderated by the previous fall white oak crop and the onset of green ‐ up in the spring. K E Y W O R D S acorns, age, harvest, spring green ‐ up, survival, Virginia, West Virginia, wild turkey Fall either ‐ sex wild turkey hunting has been popular in areas of Virginia and West Virginia where populations survived extirpation in the 20th century. However, concern for stable, low ‐ density wild turkey populations in counties with the long fall seasons led to cooperative projects between the Virginia Department of Wildlife Resources and West Virginia Division of Natural Resources to investigate potential influences on turkey populations. Joint projects offered the unique ability to compare survival and harvest of wild turkey populations under different fall and spring season frameworks. In a study of female harvest and survival rates using radio ‐ telemetry, Pack et al. (1999) reported greater fall harvest rates (12.3%) and lower survival rates (0.48) in Virginia, where the fall season was either 8 or 9 weeks long, than in West Virginia. Conversely, lower (4.3%) harvest rates and higher survival (0.52) were documented in a 4 ‐ week fall season in West Virginia. The greatest survival rate (0.59) was in eastern West Virginia, where no fall hunting was permitted. Pack et al. (1999) concluded fall hunting was additive for females and cautioned that low populations could result from longer either ‐ sex seasons. In fact, Alpizar ‐ Jara et al. (2001) showed population growth declined linearly with longer fall either ‐ sex seasons in Virginia and West Virginia. Similarly, others concluded that fall either ‐ sex hunting seasons have the potential to significantly affect wild turkey populations (Suchy et al. 1983, Little et al. 1990, Vangilder and Kurzejeski 1995). Concurrent with the research by Pack et al. (1999), Norman et al. (2004) attached leg bands to captured males and reported survival and harvest estimates using band recovery models. Norman et al. (2004) concluded that fall harvest may be compensatory for males because male survival rates were low (juvenile 0.22 – 0.23, adult 0.31) and showed little variation among 3 different fall seasons. These results differed from Pack et al. (1999), who reported greater female survival rates under shorter fall seasons with lower harvest rates. The difference in the conclusions of these 2 studies left state wild turkey program managers with questions about the potential sex ‐ specific effects of fall seasons and the effects of hunting on population size and fall and spring harvest goals. 2 of 17 | NORMAN ET AL 23285540, 2022, 2, Downloaded from https://wildlife.onlinelibrary.wiley.com/doi/10.1002/wsb.1284 by University Of Florida, Wiley Online Library on [24/10/2023]. See the Terms and Conditions (https://onlinelibrary.wiley.com/terms-and-conditions) on Wiley Online Library for rules of use; OA articles are governed by the applicable Creative Commons License Following the aforementioned research, both the Virginia and West Virginia state agencies modified their fall seasons. Virginia made changes to reduce the impact of fall hunting, whereas West Virginia created the new opportunities for fall hunting. In Virginia, the 8 ‐ or 9 ‐ week season was reduced to 6 weeks. Additionally, the fall turkey season was separated from the firearms white ‐ tailed deer ( Odocoileus virginianus ) season; this was important because about one ‐ third of the fall turkey harvest was being taken by deer hunters. Whereas Virginia shortened the fall season, West Virginia moved to provide fall hunting opportunities in counties that had not offered either ‐ sex fall hunting in modern times. Six ‐ day fall either ‐ sex seasons were created in counties where the spring kill exceeded one bird per square mile of forest for 3 years (Pack et al. 1995). Besides the key consideration of the effects of the fall season on turkey population size and sustainable harvests, state agencies are challenged to maintain or grow, depending on objectives, spring harvests. Considerations for spring season timing, length, and bag limits all potentially affect male harvests. Surveys have shown that spring hunter satisfactions are dependent on their opportunities to hear, see, and interact with gobblers (male turkeys) as much or more than their opportunities to harvest a bird (Vangilder et al. 1990, Little et al. 2000, Swanson et al. 2007, Kidd et al. 2014, Isabelle and Reitz 2015). Thus, concern for adult male populations becomes important in harvest management scenarios as they typically gobble more and are more susceptible to calling and harvest than juveniles (Lewis 1980, Ielmini et al. 1992, Hubbard and Vangilder 2005). Modeling by Vangilder and Kurzejeski (1995) indicated that spring harvest rates in excess of 35% could affect the proportion of adults in the population and negatively impact spring hunting quality. Stevens et al. (2017) recommended slightly lower (30%) male harvest rates to sustain high population levels. Thus, our goal was to conduct a multi ‐ state cooperative research project to investigate the effects of the new fall harvest strategies on male harvest and survival, including in spring seasons, using radio ‐ telemetry. The primary objectives were to estimate the key factors limiting male turkey populations: 1) annual and seasonal survival rates; 2) fall and spring harvest rates; 3) mortality causes; and 4) fall and spring season hunting effects on survival. Furthermore, because of longer ‐ lived transmitters, we were able to determine survival and harvest for 2 adult known ‐ age classes (2 and 3+ year old birds). We also monitored acorn production during the study as Steffen et al. (2001) reported that acorn availability in the fall influenced survival and harvest of female wild turkeys in Virginia and West Virginia. Steffen et al. (2001) reported consistent juvenile harvest rates regardless of acorn production. However, adult females were more vulnerable to fall hunting during years of acorn crop failures. We therefore postulated that the same effects (greater fall harvest rate) may be expected for adult males. Additionally, given the importance of gobbling and spring harvest to hunters, we investigated male survival and harvest in the spring under varying amounts of acorn production in the previous fall. We hypothesized that physical condition related to acorn production could affect vulnerability to spring harvest and survival rates. We also considered the potential effect of spring phenology on survival and harvest rates. Hunter ability to hear birds gobble diminishes when full leaf ‐ out conditions prevail, so we hypothesized that survival and harvest rates could be affected by spring green ‐ up. Finally, we evaluated 3 measures (harvest/km 2 forest, gobbling/hr, and public/private land ownership) for potential relationship to harvest or survival rates. Lint et al. (1995) documented a relationship between spring harvest and population estimates for gobblers in Mississippi. In Virginia and West Virginia, hunters were required to check their turkeys; we therefore evaluated spring harvest per square kilometer of forest for a potential relationship to telemetry ‐ based harvest and survival estimates. In addition, both states had conducted annual surveys of avid spring hunters (Norman 2003, Pack et al. 2004) to monitor gobbling, turkeys seen, and number harvested. We were interested to see if these surveys of gobbling rates were related to harvest and survival rates estimated in this study. Regulating harvest pressure on public lands is a management tool that both states would consider if evidence existed for high harvest rates and lower annual survival rates on public lands. Pressure and harvest on small public lands near human population centers, where access to private lands was limited, was a particular concern. WILD TURKEY SURVIVAL | 3 of 17 23285540, 2022, 2, Downloaded from https://wildlife.onlinelibrary.wiley.com/doi/10.1002/wsb.1284 by University Of Florida, Wiley Online Library on [24/10/2023]. See the Terms and Conditions (https://onlinelibrary.wiley.com/terms-and-conditions) on Wiley Online Library for rules of use; OA articles are governed by the applicable Creative Commons License STUDY AREA We delineated study areas by the length of the fall either ‐ sex hunting season (Figure 1). Regions 1, 2, and 3 had 25, 37, and 24 days of fall hunting, respectively. Counties in Region 4 had either 0 or 6 days of fall hunting. Region 1 included Charles City and New Kent counties, in eastern Virginia. Upland areas included oak ( Quercus spp.), mixed hardwood, and pine ( Pinus spp.) forest. Tidal rivers and marshes were common. There were limited amounts (Chickahominy Wildlife Management area, 2,111 ha) of public land in this region. Region 2 included Giles, Bland, Montgomery, and Pulaski counties in southwest Virginia. This region was in the Ridge and Valley Province, which is characterized by open valleys with wooded, steep ridges that reach 1,097 m in elevation. Extensive acreages of the Jefferson National Forest were open to the public for hunting. Region 3 included 6 counties (Greenbrier, Hampshire, Hardy, Pendleton, Pocahontas, and Randolph) in eastern West Virginia. This region included the Allegheny Front, Allegheny Mountains, and in the Eastern Panhandle, the Ridge and Valley and Great Valley Physiographic provinces. Mountain ecosystems ranged from drier chestnut oak ( Q. montana ) to mesic northern F I G U R E 1 Location of wild turkey study areas in Virginia and West Virginia, USA, 2004 – 2007. 4 of 17 | NORMAN ET AL 23285540, 2022, 2, Downloaded from https://wildlife.onlinelibrary.wiley.com/doi/10.1002/wsb.1284 by University Of Florida, Wiley Online Library on [24/10/2023]. See the Terms and Conditions (https://onlinelibrary.wiley.com/terms-and-conditions) on Wiley Online Library for rules of use; OA articles are governed by the applicable Creative Commons License hardwood forest (Strausbaugh and Core 1978). There were several state ‐ owned Wildlife Management Areas (http://www.wvdnr.gov/Hunting/WMAMap.shtm, accessed 15 July 2019) and most of the Monongahela National Forest was in Region 3. Region 4 included 9 counties (Calhoun, Lewis, Lincoln, Marion, Mason, Ritchie, Summers, Tyler, and Wirt), mostly in western West Virginia. The region included the Appalachian Plateau physiographic region. Vegetation communities were diverse (Strausbaugh and Core 1978), predominately oak ‐ hickory ( Carya spp.) with numerous Wildlife Management Areas, but the area was predominately privately owned. The spring hunting season was 31 days in Virginia and 24 days in West Virginia. The Virginia spring season opened on the second Saturday in April and lasted for the following 5 weeks, excluding Sundays. In West Virginia, the season opened on the fourth Monday in April and lasted for the following 4 weeks, excluding Sundays. Half ‐ day spring hunting occurred in both states. The annual bag limit was 3 in Virginia with no more than 2 bearded birds in the spring or 2 birds in the fall. The annual bag limit was 2 in West Virginia, with no more than one female in the fall. Turkey licenses included both fall and spring seasons in both states and neither were limited by quotas. METHO DS We captured juvenile (<1 year) and adult (>1 year) male wild turkeys during fall (August – November) and winter (January – April) 2004 – 2007, using rocket nets over bait. Sex and age (juvenile or adult) was determined using leg length and primary molt pattern (Healy and Nenno 1980). Adults were considered to be 2+ years of age. However, to further investigate the effects of age, we created known age 2 and 3+ year ‐ old classes by tracking survival of individual juvenile birds, beginning in 2004, which lived into the second and third years of the study. Birds were censored on August 31 and readmitted as either 2 or 3+ year ‐ old birds on September 1. We attached aluminum butt ‐ end leg bands and VHF transmitters (Advanced Telemetry Systems, Isanti, MN, USA) with each having an 8 ‐ hour mortality mode to the birds using marine grade shock cord (Norman et al. 1997). Birds were released where captured. We excluded turkeys dying within 14 days of capture from analyses. We evaluated survival and harvest rates in fall (October – January) and spring (April – May) periods. We monitored males weekly and quickly (~24 hr) recovered carcasses when a mortality mode was detected. We examined the carcass, transmitter, and area around the carcass to assign a cause of mortality. A field guide was developed based on existing literature and observations by staff from previous survival studies (Bumann and Stauffer 2002). Evidence of avian predation included the following: 1) feathers that were plucked and piled; 2) beak impressions on harness, transmitter, or bones; 3) transmitter antennae kinked; 4) whitewash present; 5) raptor pellets or nest nearby; and 6) bones largely intact. Mammal predation signs included: 1) feathers that had been crushed or chewed; 2) tooth marks in transmitter or bones; 3) scat or tracks present; and 4) carcass at den. Unknown predation was assigned where it appeared multiple predators or scavenging had taken place. We considered instances where the harness had been cut and the transmitters either hidden (e.g., under log), discarded (e.g., ponds, streams, dumpsters), or recovered from a poacher's residence, to be illegal kills. Birds that were shot and not recovered were considered crippling losses. Our crippling losses were considered minimal although some crippled birds could have been incorrectly classified as predation. Survival and harvest covariates Acorn production was monitored annually in Virginia (Fearer et al. 2008) and West Virginia (Pack and Igo 2003) from 2003 – 2007. Because the acorn monitoring methods differed between states, we standardized results using Z ‐ scores. In Virginia, acorn production was based on counts of acorns from 80 marked trees along 32 routes. The number of acorns were counted and then averaged on the last 60 cm of 10 randomly selected limbs on 40 marked red oak ( Q. rubra ) and 40 marked white oak species ‐ group trees per route (Sharp 1958). In contrast, a qualitative WILD TURKEY SURVIVAL | 5 of 17 23285540, 2022, 2, Downloaded from https://wildlife.onlinelibrary.wiley.com/doi/10.1002/wsb.1284 by University Of Florida, Wiley Online Library on [24/10/2023]. See the Terms and Conditions (https://onlinelibrary.wiley.com/terms-and-conditions) on Wiley Online Library for rules of use; OA articles are governed by the applicable Creative Commons License survey was conducted in West Virginia by assigning a subjective rating (0 ‐ failure, 1 ‐ poor, 2 ‐ fair, 3 ‐ good, 4 ‐ excellent) for acorn production to each oak species over a given management unit (e.g., wildlife management area, ranger district, or county) based on the observer's perception of acorn production while in the field during August and September. West Virginia used 4 classes (1 ‐ abundant, 2 ‐ common, 3 ‐ scarce, 4 ‐ species not present) in their survey and converted these ratings into an index of production by species and county by adding the percentage of observers in the county that rated production as abundant plus ½ the percentage of observers who said production was common. Gobbling rates (gobblers heard/hr) were determined for each region in similar Spring Gobbler Hunter Surveys conducted in both states from 2004 – 2007 (Norman 2003, Pack et al. 2004). Gobbling was monitored by volunteers that had been provided data forms and instructions. Gobbling was reported by county and the data were summarized based on the observations per hour. Relative gobbler density indices were based on the spring harvest/ km 2 of forest cover. Hunters were required to report their harvest at check stations in both states. We anticipated spring harvest risk would be greater in areas with higher densities based on gobbling rates and harvest rates. We investigated the potential role of spring green ‐ up on harvest rates and spring harvest risk. Elevation, longitude, and latitude were used to calculate a relative phenological index (RPI; growing degree days) value based on Hopkin's bioclimatic law. Hopkin's law states that phenological events are altered by about 4 days for each 5° change of latitude northward or longitude eastward; events are accelerated in spring and retreat in fall. Values were created for each bird on 1 April, 1 May, and 31 May based on a 30 ‐ x 30 ‐ m cell centered over each bird's trapping (and release) location. The home location for each turkey was based on land ownership (private or public) where it was trapped (Table 1). Statistical analyses We used Kaplan ‐ Meier (KM) survival curves with staggered entry (Pollock et al. 1989) to estimate annual and season survival rates using the survival package (Therneau 2020) in Program R (Version 3.4.4, R Core Team 2018). Cox proportional hazard (CPH) models were used to model the effects of covariates on survival across the 3 years of the study (Cox 1972). The predictor variables included age, year, acorn abundance (white oak, red oak), land ownership (public or private) where the turkey was trapped, RPI, presence or absence of fall hunting, the number of T A B L E 1 Wild turkey survival parameters estimated in Virginia and West Virginia, USA, 2004 – 2007. Parameter Description Age Age classes of 1, 2, 3 (know age) or 2+ (combine all adult captured and calculated ages). RPI Relative Phenology Index based on degree growing days. White acorns, red acorns Z ‐ score for white, red, and average oak acorn indices in Virginia and West Virginia. The mean of all 3 species was also included. Land Dummy variables for land ownership where the turkey was trapped (public or private). Year Years the study was conducted. Fall Hunt Dummy variables for region with no or some fall hunting. Hunt days Length of fall season (days). Gobble index Average number of gobblers heard/hr by region as reported by avid turkey hunters in the respective state Spring Gobbler Hunter Surveys. Density Spring gobbler kill/km 2 of forest in pooled counties where birds were monitored. 6 of 17 | NORMAN ET AL 23285540, 2022, 2, Downloaded from https://wildlife.onlinelibrary.wiley.com/doi/10.1002/wsb.1284 by University Of Florida, Wiley Online Library on [24/10/2023]. See the Terms and Conditions (https://onlinelibrary.wiley.com/terms-and-conditions) on Wiley Online Library for rules of use; OA articles are governed by the applicable Creative Commons License days in the fall season, gobbling index (heard/hr) for the county of harvest, and gobblers killed/km 2 of forest cover for the county of harvest. From these predictor variables, we constructed a priori models for annual, fall (October – January), and spring (April – May) seasons. We used univariate CHP analysis to qualify covariates for modeling ( P < 0.25) and further examined covariate proportionality ( P > 0.05). Annual cycles began October 14, 13, and 12 for 2004, 2005, and 2006, respectively. We used Akaike's Information Criterion adjusted for small sample size (AIC c ) for model selection (Burnham and Anderson 2002). We used Akaike weights ( w i ) to evaluate the strength of evidence among competing models and considered the most plausible models to be those ≤ 2 AIC c units from the top model (Burnham and Anderson 2002). We used model averaging when there were several competing models (Burnham and Anderson 2002). Harvest rates were estimated for fall and spring hunting seasons by considering harvest as the only mortality events while right censoring other mortality sources. R E S U L T S We tagged 401 males; 204 in Virginia and 197 in West Virginia (Table 2). Age ratios of trapped birds were similar between Virginia (52.9% adults) and West Virginia (54.8% adults). We censored 91 (22.7%) birds due to slipped harness (6), harness ‐ induced mortality (2), failing to survive a 2 ‐ weeks conditioning period (45), lost contact (24), lost contact – suspected battery failure (12), and lost contact – suspected poaching (2). We determined cause of death for 209 birds. The primary cause of death was hunting: 41.6% (n = 87) in the spring season, 3.8% ( n = 8) in the fall season, and 1.4% ( n = 3) to crippling losses. We identified 25.4% ( n = 53) of mortalities as predation (23 mammal, 15 avian, and 15 unknown). Predation and poaching peaked during the fall and spring hunting seasons (Table 3). Poachers killed thirty ‐ six birds (17.2%). Annual poaching losses were identical between Virginia and West Virginia ( n = 18, 8.6%); however, poaching was greater in the fall in Virginia, whereas poaching was greater in the spring in West Virginia. The balance of losses was attributed to other miscellaneous causes (5.7%, n = 12), accidents (3.8%, n = 8), and disease (1%, n = 2). Collisions with vehicles were the primary cause of accidental losses. There were 101 birds alive at the end of the study. Confidence intervals for annual survival of 2 and 3+ year ‐ old birds overlapped (Table 4); therefore, we combined all adults (2+). Annual survival of all adults was 0.63 (95% CI = 0.58 – 0.69). Likewise, confidence intervals for spring harvest rates for the 2 and 3+ year age classes overlapped. Spring harvest rate of all adults was 25% (95% CI = 20 – 29%; Table 4). Annual survival of juvenile birds (0.74; 95% CI = 0.68 – 0.79) was greater than adults (0.63; 95% CI = 0.58 – 0.68). Most mortality took place in April (Figure 2). Spring harvest mortality rates of juveniles (0.07; 95% CI = 0.03 – 0.11) were lower than adults (0.25; 95% CI = 0.20 – 0.29). Confidence intervals for annual survival and spring harvest mortality rate estimates overlapped for the 2 states (Table 4). T A B L E 2 Number of wild turkeys captured and marked in Virginia and West Virginia, USA, 2004 – 2007. Study areas 2004 – 2005 2005 – 2006 2006 – 2007 Total Virginia Number captured 111 68 25 204 Number reentered 53 77 130 West Virginia Number captured 102 36 59 197 Number reentered 57 58 115 Total 221 217 208 646 WILD TURKEY SURVIVAL | 7 of 17 23285540, 2022, 2, Downloaded from https://wildlife.onlinelibrary.wiley.com/doi/10.1002/wsb.1284 by University Of Florida, Wiley Online Library on [24/10/2023]. See the Terms and Conditions (https://onlinelibrary.wiley.com/terms-and-conditions) on Wiley Online Library for rules of use; OA articles are governed by the applicable Creative Commons License Spring harvest rate trends varied by state (Figure 3A, B). Spring harvest rates of both juveniles and adults in Virginia declined steadily through the study, whereas spring harvest rates of adults in West Virginia were stable and juvenile spring harvest rates increased. Overall, fall survival rates were high (0.90; 95% CI = 0.87 – 0.93) and fall harvest rates were low (3%; 95% CI = 1 – 4%; Table 5). Confidence intervals for fall survival overlapped for all 4 regions despite the wide range of season frameworks. Fall harvest rates ranged from 0 to 5% among the 4 regions of the study. T A B L E 3 Seasonal losses to predation and illegal poaching in male wild turkeys in Virginia and West Virginia, USA, 2004 – 2007. Season a 2004 – 2007 Fall Winter Spring Summer Total Mortality cause N % N % N % n % n % Predation Avian 7 31.8 3 60 3 15.8 2 28.6 15 28.3 Mammal 9 40.9 2 40 9 47.4 3 42.9 23 43.4 Unknown 6 27.3 0 0 7 36.8 2 28.6 15 28.3 Total 22 41.5 5 9.4 19 35.8 7 13.2 53 100 Illegal VA 8 66.7 2 50 5 35.7 3 50 18 50 WV 4 33.3 2 50 9 64.3 3 50 18 50 Total 12 33.3 4 11.1 14 38.9 6 16.7 36 100 a Season dates were as follows: Fall (Oct – Jan), Winter (Feb – Mar), Spring (Apr – May), and Summer (Jun – Sep). T A B L E 4 Annual survival (S ) and spring harvest ( H ) mortality rates for male wild turkeys in Virginia (VA) and West Virginia (WV), USA, 2004 – 2007. Known age birds (2, 3 years) were based on tracking survival of juvenile birds trapped in 2004 into the second and third years, respectively, of the study. Otherwise, all adults were included in the 2+ age class over the entire study period (2004 – 2007). Area Age class S 95% LCI ‐ 95% UCI H (%) 95% LCI ‐ 95% UCI n VA Juvenile 0.77 0.70 – 0.85 4 0 – 10 127 WV Juvenile 0.70 0.63 – 0.79 9 2 – 14 124 VA&WV Juvenile 0.74 0.68 – 0.79 7 3 – 11 251 VA&WV 2 0.64 0.59 – 0.70 25 19 – 31 274 VA&WV 3+ 0.58 0.47 – 0.73 23 13 – 31 57 VA&WV 2+ 0.63 0.58 – 0.68 25 20 – 29 331 VA 2+ 0.65 0.58 – 0.72 27 19 – 33 181 WV 2+ 0.62 0.55 – 0.70 23 15 – 29 150 VA Combined 0.70 0.65 – 0.75 20 14 – 25 308 WV Combined 0.66 0.60 – 0.72 17 12 – 22 274 8 of 17 | NORMAN ET AL 23285540, 2022, 2, Downloaded from https://wildlife.onlinelibrary.wiley.com/doi/10.1002/wsb.1284 by University Of Florida, Wiley Online Library on [24/10/2023]. See the Terms and Conditions (https://onlinelibrary.wiley.com/terms-and-conditions) on Wiley Online Library for rules of use; OA articles are governed by the applicable Creative Commons License There were 3 competing models for survival in the spring season (April – May; Table 6). Model averaging results suggested 3 significant covariates influenced spring survival: Age (2+), white oak acorn abundance, and RPI (Table 7). Survival was lower with older birds and was lower when white oak acorns were abundant the previous fall. Spring survival increased as RPI (spring green ‐ up) increased. There were 2 competing models for harvest risk (other mortality sources excluded) for the spring season; however, their model weights ( ≤ 0.40) were not compelling (Table 8). We therefore averaged the top 2 models (Table 9). Spring harvest risk increased with age, declined with RPI, and was lower in 2007. D I S C U S S I O N Fall harvest rates of male wild turkeys were low among the 4 regions, regardless of the fall season structure. Because fall hunting mortality was low, the effects of fall hunting on the male populations, even if additive, likely were minimal in the Virginias, because male annual survival rates were high. Furthermore, fall hunting has declined F I G U R E 2 Annual survival for adult (2+) and juvenile wild turkeys in Virginia and West Virginia, USA, 2004 – 2007. WILD TURKEY SURVIVAL | 9 of 17 23285540, 2022, 2, Downloaded from https://wildlife.onlinelibrary.wiley.com/doi/10.1002/wsb.1284 by University Of Florida, Wiley Online Library on [24/10/2023]. See the Terms and Conditions (https://onlinelibrary.wiley.com/terms-and-conditions) on Wiley Online Library for rules of use; OA articles are governed by the applicable Creative Commons License significantly in Virginia since the 2004 – 2007 study, in large part to reductions in the fall season length and separation from firearms deer hunting seasons. Trend analyses indicated fall harvest in Virginia has declined 4.3% ( P = 0.048) annually since 2008 and the number of fall turkey hunters has declined approximately 25% since 2001 (Virginia Department of Wildlife Resources, unpublished reports). Given this decline in hunter numbers and declining harvests, it appears fall hunting has minimal impact on male wild turkeys in Virginia. Annual survival rates of juveniles in our study were greater than many studies in the eastern U.S. (Table 10). Annual survival rates of adults were the highest reported in the region. The highest juvenile survival estimates were derived from banding studies, which may not be directly comparable because they did not capture mortalities from illegal or crippling losses (Diefenbach et al. 2012). In the current study, illegal losses equaled 36% of the total fall and spring legal harvest. Furthermore, our estimates included many birds that were trapped in September and October, and therefore annual survival estimates were based on 8 – 10 months of monitoring in the year those birds F I G U R E 3 Harvest rates of (A) juvenile and (B) adult (2+ years ‐ old) male wild turkeys in spring (April – May) in Virginia and West Virginia, USA, from 2004 – 2007. 10 of 17 | NORMAN ET AL 23285540, 2022, 2, Downloaded from https://wildlife.onlinelibrary.wiley.com/doi/10.1002/wsb.1284 by University Of Florida, Wiley Online Library on [24/10/2023]. See the Terms and Conditions (https://onlinelibrary.wiley.com/terms-and-conditions) on Wiley Online Library for rules of use; OA articles are governed by the applicable Creative Commons License were captured. Conversely, because most studies trapped only in winter, survival estimates were based on shorter periods of time (4 – 5 months). As an example of the potential effect of capture season, Conner et al. (2006) documented lower survival estimates of juvenile females captured in fall than those captured in winter. Perhaps the high survival rates in this study were due to low harvest rates, particularly low harvest rates of juvenile males. Juvenile harvest rates in other states are typically double what we observed (Table 10). Perhaps spring hunters in the Virginias pass on harvesting juvenile males more than hunters in some other states or regions. Harvest rates of adult males were also at the low end of the range observed in other studies. Anecdotally, demand and participation among resident and non ‐ resident spring hunters appeared high. Additionally, the impacts of the half ‐ day hunting in the spring season are unknown but may have contributed to lower harvest rates. Concern for low male survival and concern for the effects of fall harvest on male populations by Norman et al. (2004) led to the current study. Our results were reassuring that fall season effects on male survival were minimal in the Virginias. Notably, the findings of Norman et al. (2004) was based on band return models, whereas we used known fates of radio ‐ marked birds. Hence, the low survival rates reported in Norman et al. (2004) could be the result of band loss. Diefenbach et al. (2009) reported butt ‐ end band loss (the type used by Norman et al. [2004] and in this study) greater than 50% after 15 months and suggested low survival estimates could be the result of band loss. However, Butler et al. (2011) reported lower band loss rates (14%) at 15 months in another study of butt ‐ end T A B L E 5 Kaplan ‐ Meier (KM) survival ( S ) and hunting mortality ( H ) estimates for male wild turkeys during the legal fall hunting seasons (October – January) in Virginia (VA) and West Virginia (WV), USA, 2004 – 2007. Kaplan ‐ Meier hunting mortality estimates used legal fall harvest as the only mortality source. Fall days are the length of the fall season and overlap days are the days in the fall season that overlapped a firearms deer season. Region 1 was centered in eastern VA, Region 2 was in southwest VA, Region 3 was eastern WV, and Region 4 was in western WV. Only one juvenile bird was legally harvested in the study. Region Fall days (overlap days) Year n S rate 95% LCI ‐ 95% UCI H rate 95% LCI ‐ 95% UCI 1 25 (19) 2004 15 0.73 0.53 – 1 0 0 – 0 2005 20 0.79 0.63 – 1 0 0 – 0 2006 25 0.88 0.76 – 1 0 0 – 0 2004 – 2007 60 0.81 0.72 – 0.92 0 0 – 0 2 37 (25) 2004 46 0.84 0.74 – 0.96 5 0 – 12 2005 35 0.91 0.83 – 1 6 0 – 13 2006 53 0.88 0.81 – 0.98 4 0 – 9 2004 – 2007 134 0.89 0.83 – 0.94 5 1 – 9 3 24 (0) 2004 25 0.96 0.89 – 1 0 0 – 0 2005 23 0.96 0.88 – 1 0 0 – 0 2006 28 0.86 0.74 – 1 0 0 – 0 2004 – 2007 76 0.92 0.86 – 0.98 0 0 – 0 4 0 or 6 2004 39 0.95 0.88 – 1 3 0 – 8 (0) 2005 35 1 1 – 1 3 0 – 8 2006 47 0.93 0.87 – 1 2 0 – 7 2004 – 2007 121 0.96 0.92 – 0.99 3 0 – 6 All 0 – 37 2004 – 2007 309 0.90 0.87 – 0.93 3 1 – 4 WILD TURKEY SURVIVAL | 11 of 17 23285540, 2022, 2, Downloaded from https://wildlife.onlinelibrary.wiley.com/doi/10.1002/wsb.1284 by University Of Florida, Wiley Online Library on [24/10/2023]. See the Terms and Conditions (https://onlinelibrary.wiley.com/terms-and-conditions) on Wiley Online Library for rules of use; OA articles are governed by the applicable Creative Commons License band retention. Even if band losses increased with time and eventually become problematic for survival estimates, it is possible that harvest estimates based on band returns remain useful if most legal hunting mortalities occur prior to the time when significant band loss occurs. In our study, most turkeys that were harvested were killed within a year of trapping and band loss of fall harvested birds was low. It was surprising there was no difference in spring harvest or annual survival between the states given there were differences in timing and duration of the spring seasons. The spring season opened 7 – 13 days earlier and was 7 days longer in Virginia than West Virginia. The annual bag limit was also higher in Virginia (3) than West Virginia (2). Chamberlain et al. (2012) reported a 2 ‐ fold increase in annual survival of male wild turkeys in areas of conservative (2 ‐ bird limit) spring season compared to more liberal (3 ‐ bird) seasons in Louisiana. Perhaps effects of the timing and duration of the spring season and annual bag limits would have been detected in a longer (5 – 10 yr) study. Although spring harvest rates in Virginia and West Virginia were low at the beginning of the study, they steadily increased in the second and third years. Between 2008 and 2020, reported spring harvest increased 1.9% ( P = 0.02) annually in Virginia and 1.7% ( P = 0.04) annually in West Virginia, and estimated numbers of spring hunters T A B L E 6 Model selection for spring (April – May) season survival for male wild turkeys, using Akaike's Information Criterion corrected for small sample sizes (AIC c ) for candidate Cox proportional hazard models, in Virginia and West Virginia, USA, 2004 – 2007. Included are model rank, model name, number of parameters ( K ), log ‐ likelihood (LL), Akaike's Information Criterion adjusted for small sample size (AIC c ), model differences ( Δ AIC c ), and model weight ( w i ). Models 1 – 3 were considered competing ( Δ AIC c < 2). Rank Model K LL AIC c Δ AIC c w i 1 Age + RPI + White Oak 3 − 687.4 1381 0 0.37 2 Age + RPI + White Oak + Gobble Index 4 − 687.2 1383 1.65 0.16 3 Age + RPI + White Oak + Year 5 − 686.1 1383 1.74 0.15 4 Age + White Oak 2 − 689.8 1384 2.65 0.10 5 Age + White Oak + Gobble Index 3 − 688.8 1384 2.83 0.09 6 Age + RPI + Year + White Oak + Gobble Index 6 − 686.1 1385 3.96 0.05 7 Age + White Oak + Year 4 − 688.6 1386 4.43 0.04 8 Age + White Oak + Gobble Index + Year 5 − 688.2 1387 5.78 0.02 9 Age + RPI + Year 4 − 689.8 1388 6.89 0.01 10 Age + RPI 2 − 692 1388 7.13 0.01 T A B L E 7 Effect sizes for covariates affecting spring season survival of male wild turkeys in Virginia and West Virginia, USA (2004 – 2007). Estimates were obtained by averaging across 3 competing models ( Δ AIC c < 2.0) from a set of 10 a priori candidate models (Table 6). Hazard covariates Estimate SE Z value P (>| z |) Age (2+) 1.15 0.26 4.4 <0.001 White oak 0.23 0.08 2.92 0.004 RPI − 0.02 0.008 2.24 0.03 Year (2006) 0.24 0.32 0.74 0.46 Gobble index 0.008 0.01 0.70 0.49 Year (2007) − 0.15 0.26 0.57 0.57 12 of 17 | NORMAN ET AL 23285540, 2022, 2, Downloaded from https://wildlife.onlinelibrary.wiley.com/doi/10.1002/wsb.1284 by University Of Florida, Wiley Online Library on [24/10/2023]. See the Terms and Conditions (https://onlinelibrary.wiley.com/terms-and-conditions) on Wiley Online Library for rules of use; OA articles are governed by the applicable Creative Commons License in Virginia increased 23% between 2006 and 2015 (Virginia Department of Wildlife Resources, unpublished reports). We observed an age effect on survival, as have studies conducted in Georgia (Ielmini et al. 1992), Missouri (Hubbard and Vangilder 2005), Kentucky (Wright and Vangilder 2005), New Jersey (Eriksen et al. 2011), Ohio, Pennsylvania, and New York (Diefenbach et al. 2012), and Louisiana (Chamberlain et al. 2012). We therefore expected our oldest age group (known age 3 ‐ year ‐ old birds) would have great