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

Abstract

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 δ 13C and 13.8% 0 for δ 15N. This contrasts with the low range in data for individuals from nearby locations (1.8% 0 for δ 13C and 1.2% 0 for δ 15N). Most variability in δ 15N likely reflects inter-regional variations in soil δ 15N. However, deer tend to have low δ 15N possibly as a result of consuming leaves from plants with woody growth forms. Low δ 15N 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 δ 15N probably from direct effects of water stress on animal δ 15N. The δ 13C data indicate that most deer ate a normal diet of C 3 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 δ 13C and δ 15N 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 δ 13C and δ 15N values.