Deer Oh Deer: Seasonal Diet Variation In Northeastern White-Tailed Deer

Abstract

In Princeton, New Jersey, lives a population of Odocoileus virginianus, or Northeastern white-tailed deer, a species which is currently negatively impacting North American ecosystems due to overabundance. The expansion of invasive species is another ecological concern, so we set out to address how these two processes interact, and their impacts on the environment. We performed a survey of Princeton residents to validate that deer overabundance is a locally relevant concern. The survey revealed that residents generally held a negative opinion about deer impacts locally, both on human and natural spaces. I then used DNA metabarcoding on 169 Northeastern white-tailed deer fecal samples to characterize the composition of deer diets and how they vary seasonally. I tested the hypothesis that deer diets primarily rely on native understory vegetation, including grasses and forbs, as a result of the abundance and nutritional quality, but would switch to eating non-native trees and shrubs in the winter. We found that deer diet components vary seasonally, and this variation entails changes in group size patterns and diet quality. From elemental composition of 50 deer dung samples, we found that C:N of deer dung increased in the winter, suggesting that deer diet quality declines in the winter in accordance with seasonal changes in diet composition. Additionally, individuals in larger groups had lower quality diets, though this was not as a result of intraspecific competition. This research worked with an accessible study system to provide insight about regional environmental and social concerns, with the goal of assessing overpopulation, invasive species, and climate change on these scales.