White‐Tailed deer population dynamics following Louisiana black bear recovery
Changing predator communities have been implicated in reduced survival of white‐tailed deer (Odocoileus virginianus) fawns. Few studies, however, have used field‐based age‐specific estimates for survival and fecundity to assess the relative importance of low fawn survival on population growth and harvest potential. We studied white‐tailed deer population dynamics on Tensas River National Wildlife Refuge (TRNWR) in Louisiana, USA, where the predator community included bobcats (Lynx rufus), coyotes (Canis latrans), and a restored population of Louisiana black bear (Ursus americanus luteolus). During 2013–2015, we radio‐collared and monitored 70 adult (≥2.5 yrs) and 21 yearling (1.5‐yr‐old) female deer. Annual survival averaged 0.815 (95% CI=0.734–0.904) for adults and 0.857 (95% CI=0.720–1.00) for yearlings. We combined these estimates with concurrently collected fawn survival estimates (0.27; 95% CI=0.185–0.398) to model population trajectories and elasticities. We used estimates of nonhunting survival (annual survival estimated excluding harvest mortality) to project population growth (λ) relative to 4 levels of harvest (0, 10%, 20%, 30%). Finally, we investigated effects of reduced fawn survival on population growth under current management and with elimination of female harvest. Despite substantial fawn predation, the deer population on TRNWR was increasing (λ=1.06) and could sustain additional female harvest; however, the population was expected to decline at 20% (λ=0.98) and 30% (λ=0.94) female harvest. With no female harvest, the population was projected to increase with observed (λ=1.15) and reduced fawn survival (λ=1.02), but the population could not sustain current female harvest (10%) if fawn survival declined (λ=0.90). For all scenarios, adult female survival was the most elastic parameter. Given the importance of adult female survival, the relative predictability in response of adult survival to harvest management, and the difficulty in altering fawn survival, reducing female harvest is likely the most efficient approach to compensate for low fawn survival. On highly productive sites such as ours, reduction, but not necessarily elimination, of harvest can mitigate effects of low fawn survival on population growth.