Gobbling chronology of eastern wild turkeys in South Carolina

Abstract

Eastern wild turkeys (Meleagris gallopavo silvestris) use a polygynous-promiscuous mating system, wherein males compete for mating opportunities and communicate with females via courtship behaviors. One courtship behavior is vocalization (gobbling), which attracts females and signals dominance to other males. However, temporal variation in gobbling activity may be influenced by external stimuli, environmental variation, and hunter activity. Gobbling activity is a key determinant of hunter satisfaction, and gobbling chronology is often used by state agencies to inform regulatory processes. To identify factors influencing gobbling activity, we evaluated daily gobbling chronology on 3 sites in South Carolina, USA (Webb Wildlife Management Area [WMA] Complex, Savannah River Site, Crackerneck WMA) with different levels of hunter activity. We used autonomous recording units (ARUs; n ¼ 45) across 8,280 days to collect 53,937 hours of ambient sound recordings and identified 68,426 gobbles. Gobbling activity varied daily and site interacting with minutes since sunrise best predicted daily gobbling activity. We noted distinct differences in predicted numbers of gobbles between hunted sites and an unhunted site, suggesting that hunting may be an important determinant of gobbling activity. Across our study sites, we observed that !72% of gobbling activity occurred between 30 minutes before and 60 minutes after sunrise. We found no clear evidence of well-defined unimodal or bimodal peaks in daily or weekly gobbling activity. Across sites, <44% of gobbling activity occurred during legal hunting seasons in South Carolina, with between 30% and 48% of gobbling activity occurring after legal hunting seasons. Because hunter satisfaction is primarily influenced by gobbling activity, wildlife managers in South Carolina may consider adjusting dates of turkey hunting seasons to correspond hunting with periods when most gobbling occurs. Ó 2018 The Wildlife Society.

Hunting and Nesting Phenology Influence Gobbling of Wild Turkeys

“…Male wild turkeys are the only gamebird in the conterminous United States hunted specifically during peaks in reproductive activities (Chamberlain et al , Isabelle et al ), and hunting is generally timed to expose hunters to periods when gobbling activity is greatest (Miller et al , Lehman et al ). Gobbling not only attracts females but also serves to maintain established male dominance hierarchies (Healy , Kienzler et al , Wightman et al ). We offer that hunting potentially removes a segment of vocal males from the landscape while also prompting remaining males to reduce gobbling (Lehman et al , Chamberlain et al ), and in our study, cease gobbling well before the end of the reproductive season.…”

“…We placed microphones at a height of approximately 10 m in pine trees to reduce interference associated with understory and midstory vegetation (Colbert et al ). We set ARUs to collect data from 0500 hours to 1100 hours, which encompasses >85% of daily gobbling activity (Wightman et al ).…”

“…We searched audio files for gobbles using the call recognition software (CRS) Raven Pro versions 1.4 and 1.5 (Cornell Laboratory of Ornithology, Ithaca, NY, USA; Chamberlain et al , Wightman et al ). The CRS allowed gobbles to be assessed auditorily and visually.…”

“…Because of expected high false positive rates (Colbert ), we visually and auditorily verified all potential gobbles. We stored gobbles in a selection table, which included date and time (Chamberlain et al , Wightman et al ).…”

“…We placed microphones at a height of approximately 10 m in pine trees to reduce interference associated with understory and midstory vegetation (Colbert et al 2015). We set ARUs to collect data from 0500 hours to 1100 hours, which encompasses >85% of daily gobbling activity (Wightman et al 2019). We searched audio files for gobbles using the call recognition software (CRS) Raven Pro versions 1.4 and 1.5 (Cornell Laboratory of Ornithology, Ithaca, NY, USA; Chamberlain et al 2018, Wightman et al 2019.…”