Faecal stable isotope analysis in white-tailed deer ( Odocoileus virginianus ), an alternative method for alimentary ecology studies

Abstract

Stable isotope analysis of tissues offers an alternative to study the alimentary ecology in wild animal populations. However, estimating the difference between diet and tissue isotope values (trophic shifts) is essential because it is not consistent for all tissues and species. Trophic shifts for white-tailed deer ( Odocoileus virginianus ) antler, hair and blood, have been determined and allow for dietary reconstructions. Nevertheless, these tissues are difficult to obtain in areas where deer occur at low densities and their collection may involve unwanted manipulation of wild animals. Alternatively, faecal isotope analyses are advantageous because samples are easy to obtain in the field, their isotopic composition is related to the food ingested and allow for documenting short-term diet variability. Therefore, we estimated diet-faeces trophic shifts in white-tailed deer fed on a constant diet. The observed diet-faeces trophic shifts (0.81‰ for δ13C and 2.13‰ for δ15N) were different to the trophic shifts reported for other herbivores. However, our estimates proved to be useful when applied to a mixing model to quantify the contributions of multiple food sources to the deer’s diet. Our diet-faeces trophic shift estimates are reliable measurements which can be used to expand the potential of stable isotope analyses in white-tailed deer.