Abstract
Wildlife population dynamics are modulated by abiotic and biotic
factors, typically climate, resource availability, density-dependent
effects, and predator-prey interactions. Understanding if human-caused
disturbances shape these processes is needed for the conservation and
management of ecological communtiies within increasingly human-dominated
landscapes. Garnering this understanding is difficult due to lack of
long-term longitudinal data on wildlife populations, human-mediated
disturbances, climate and predator density on ungulate population
dynamics has been under-studied. Using a 50-year time series (1962-2012)
on mule deer (Odocoileus hemionus) demographics, seasonal weather,
predator density, oil and gas development patterns from the North Dakota
Badlands to investigate long-term effects of landscape-level
disturbance. We aimed to evaluate if harsh weather conditions
in-combination with energy development and predators affected fall mule
deer recruitment. We found that density-dependent effects and harsh
seasonal weather primarily drove recruitment in the North Dakota
Badlands. Recruitment was further shaped by interacting effects of harsh
seasonal weather and predator presence in the form of high coyote
density. Additionally, we found that fall recruitment was subtly
modulated by interactions between seasonal weather and energy
development (i.e., lower recruitment when harsher weather was combined
with higher density of active oil and gas wells), and that the combined
effect of predator density and energy development was not interactive
but rather additive. Our analysis demonstrates the effect of energy
development by modulating mule deer recruitment fluctuations concurrent
with main recruitment drivers being biotic (density-dependency, habitat,
predation) and abiotic (harsh seasonal weather, woody vegetation
encroachment). A pattern emerges of density dependence, presumably due
to limited quality habitat, being the primary factor influencing fall
fawn recruitment in mule deer. Secondarily, stochastic weather events
periodically cause dramatic declines in recruitment. Finally, the
interactions between human disturbance and predation can be additive to
the aforementioned drivers of recruitment and subsequently cause further
declines.