Stable isotopes of nitrogen and carbon of North American white-tailed deer and implications for paleodietary and other food web studies

The carbon and nitrogen isotopic ratios of bone collagen from freshly killed specimens of North American white-tailed deer (Odocoileus virginianus) show large, inter-regional ranges of 9.7%0 for δ13C and 13.8%0 for δ15N. This contrasts with the low range in data for individuals from nearby locations (1.8%0 for δ13C and 1.2%0 for δ15N).Most variability in δ15N likely reflects inter-regional variations in soil δ15N. However, deer tend to have low δ15N possibly as a result of consuming leaves from plants with woody growth forms. Low δ15N also result from consumption of agricultural plants in areas where legumes are grown or fertilizers used. In contrast, deer from dry areas can have high δ15N probably from direct effects of water stress on animal δ15N.The δ13C data indicate that most deer ate a normal diet of C3 plants. However, some deer from agricultural areas likely ate corn while others from dry areas may have consumed some grasses during times of population stress and starvation.A large range in the δ13C and δ15N data remains even after agricultural effects are accounted for. Such variation for a single species of non-migratory, browsing herbivore indicates that human paleodietary or other food web studies should include baseline estimates of local dietary plant and animal δ13C and δ15N values.