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Your search keyword '"DeVivo, Melia T."' showing total 10 results
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2. White‐tailed deer population dynamics in a multipredator landscape shaped by humans.

Author

Ganz, Taylor R., Bassing, Sarah B., DeVivo, Melia T., Gardner, Beth, Kertson, Brian N., Satterfield, Lauren C., Shipley, Lisa A., Turnock, Benjamin Y., Walker, Savanah L., Abrahamson, Derek, Wirsing, Aaron J., and Prugh, Laura R.

Subjects
DEER populations, WHITE-tailed deer, POPULATION dynamics, WOLVES, TOP predators, BOBCAT, LOGGING
Abstract

Large terrestrial mammals increasingly rely on human‐modified landscapes as anthropogenic footprints expand. Land management activities such as timber harvest, agriculture, and roads can influence prey population dynamics by altering forage resources and predation risk via changes in habitat, but these effects are not well understood in regions with diverse and changing predator guilds. In northeastern Washington state, USA, white‐tailed deer (Odocoileus virginianus) are vulnerable to multiple carnivores, including recently returned gray wolves (Canis lupus), within a highly human‐modified landscape. To understand the factors governing predator–prey dynamics in a human context, we radio‐collared 280 white‐tailed deer, 33 bobcats (Lynx rufus), 50 cougars (Puma concolor), 28 coyotes (C. latrans), and 14 wolves between 2016 and 2021. We first estimated deer vital rates and used a stage‐structured matrix model to estimate their population growth rate. During the study, we observed a stable to declining deer population (lambda = 0.97, 95% confidence interval: 0.88, 1.05), with 74% of Monte Carlo simulations indicating population decrease and 26% of simulations indicating population increase. We then fit Cox proportional hazard models to evaluate how predator exposure, use of human‐modified landscapes, and winter severity influenced deer survival and used these relationships to evaluate impacts on overall population growth. We found that the population growth rate was dually influenced by a negative direct effect of apex predators and a positive effect of timber harvest and agricultural areas. Cougars had a stronger effect on deer population dynamics than wolves, and mesopredators had little influence on the deer population growth rate. Areas of recent timber harvest had 55% more forage biomass than older forests, but horizontal visibility did not differ, suggesting that timber harvest did not influence predation risk. Although proximity to roads did not affect the overall population growth rate, vehicle collisions caused a substantial proportion of deer mortalities, and reducing these collisions could be a win–win for deer and humans. The influence of apex predators and forage indicates a dual limitation by top‐down and bottom‐up factors in this highly human‐modified system, suggesting that a reduction in apex predators would intensify density‐dependent regulation of the deer population owing to limited forage availability. [ABSTRACT FROM AUTHOR]

Published
2024
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7. Wildlife whodunnit: forensic identification of predators to inform wildlife management and conservation.

Author

Ganz, Taylor R., DeVivo, Melia T., Reese, Ellen M., and Prugh, Laura R.

Subjects
*WILDLIFE conservation, *PUMAS, *WILDLIFE management, *IDENTIFICATION of the dead, *ELK, *BOBCAT
Abstract

Genetic evidence at predation sites is rapidly improving predator‐prey interaction studies and can provide information beyond field‐based investigations. However, factors contributing to the retention of genetic evidence have received limited investigation in a field setting, and researchers have yet to leverage genetic evidence to improve traditional field investigations. Using data from 61 mortality investigations of mule deer (Odocoileus hemionus), white‐tailed deer (O. virginianus), and elk (Cervus canadensis), we evaluated factors influencing predator DNA amplification success and misidentification of predators in field investigations. We found that predator DNA was detected more for prey with higher body mass (18.5% increase per standard deviation [23.1 kg] in carcass body mass above the mean [32.8 kg]). Predator DNA was also 27.0% more likely to amplify when collected from kill sites that had not undergone a freeze‐thaw cycle between the mortality and the investigation. The delay between the kill and the investigation, the swabbing surface, and the amount of precipitation did not influence amplification of predator DNA. Misidentifications of the predator based on the field ID were not influenced by the investigation delay or investigator confidence level, suggesting that investigators should collect genetic evidence even when they feel certain about the predator. Errors in identifying the predator during the field investigation increased for prey with smaller body mass, and the predator was actually more likely to be misidentified than correctly identified for fawns and calves < ~21 kg. Black bears (Ursus americanus), bobcats (Lynx rufus), cougars (Puma concolor), coyotes (Canis latrans), and wolves (C. lupus) were equally likely to be missed in a field investigation, but bobcats tended to be falsely assigned more than expected and cougars were falsely assigned as the predator less than expected. Using genetic evidence as validation, we showed how patterns of predation and the field signs left by predators differed for some species depending on the size of the prey. Our findings should help researchers and managers to optimize their use of genetics to enhance field investigations. [ABSTRACT FROM AUTHOR]

Published
2023
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