Hunting and Nesting Phenology Influence Gobbling of Wild Turkeys

Abstract

Wild turkeys (Meleagris gallopavo) use a polygynous mating system whereby males engage in multiple courtship behaviors, including vocalizations (gobbling) to attract females and compete with other males for breeding opportunities. Males must balance the risk of courtship behaviors with the reproductive potential of each courtship behavior. Male turkeys are primarily hunted during the reproductive period, so the associated risk of courtship behaviors is increased. Many state agencies attempt to set hunting season frameworks that maximize hunter satisfaction by allowing hunting when gobbling activity is greatest and most females are theoretically incubating nests, but the relationship between gobbling activity and nesting phenology is unclear. We used autonomous recording units and global positioning system transmitters to monitor gobbling activity by male turkeys and reproductive behaviors of female turkeys in the Piedmont region of Georgia, USA. We used 13,177 gobbles, behavioral data from 82 females during the reproductive season, and daily estimates of harvest of males by hunters to examine relationships between daily gobbling activity, cumulative removal of males, and reproductive behaviors (laying, incubating) of females during 2017–2018. We observed a weak negative relationship between daily gobbling activity and gobbling activity the following day. As the reproductive season progressed, gobbling activity decreased. As the proportion of females engaged in laying or incubating behaviors increased, expected daily gobbling activity increased. Conversely, we observed that hunting and removal of males had a negative effect on daily gobbling activity, and this effect was disproportionately greater than the positive effect of female reproductive behaviors. Our findings suggest that hunting and removal of males are important determinants of gobbling activity, and that corresponding reductions in gobbling activity may have mediating effects on the mating system of wild turkeys. © 2019 The Wildlife Society.

Hunting Activity Effects on Roost Selection by Male Wild Turkeys

“…Hunting activity influences male turkey space use, movements, and calling (Kienzler et al 1995, Lehman et al 2005, Wightman et al 2019, Wakefield et al 2020, and can alter habitat selection in other species (Lone et al 2015, Padié et al 2015. Males selected pines less after the onset of hunting season.…”

“…We used 1 March as a start date so that we could monitor space use and roost selection when gobbling activity increases during early portions of the reproductive period (Chamberlain et al , Wightman et al ). Likewise, we used 17 April as an end date because gobbling activity essentially ceased on our study sites by this date (Wakefield et al ). Using these start and end dates also allowed us to analyze roost selection by males within 2 comparable temporal periods (i.e., same number of days) before and after the onset of hunting.…”

“…We used the Euclidean distance tool in ArcMap 10.3 (Esri, Redlands, CA, USA) to measure distance (m) to each vegetation type from each roost and random location. We buffered both known and random roost locations by 250 m because that distance approximates the known distance at which autonomous recording units used in other portions of our research (Wakefield et al ) can record gobbling activity at roost sites (see Colbert et al ). We then extracted the average NDVI value within each buffer as a measure of vegetation density.…”

“…) and surrounding privately owned properties in the Piedmont region of Georgia during 2017–2018. For a detailed description of the study sites, please see Wakefield et al ().…”

“…Gobbling is the most prominent auditory signal used by male turkeys, and is a loud vocalization that presumably conveys fitness potential to females and hierarchical dominance to other males (Bevill , Miller et al , Healy and Powell , Weir et al ). Gobbling activity across the reproductive season is variable, and is influenced by female receptivity (Scott and Boeker , Bevill , Norman et al , Chamberlain et al ), and hunting activity (Kienzler et al , Lehman et al , Wightman et al , Wakefield et al ). Daily gobbling activity is focused at or immediately following sunrise when males are perched on or located close to their nighttime roost (Bevill , Hoffman , Wightman et al ).…”