Hoof Growth Rates of the European Roe Deer (Capreolus capreolus) for Dating the Hoof’s Isotopic Archive

Hooves preserve the isotopic information laid down during their growth and may be used for reconstruction of animal feeding history. To assign certain positions along hooves to corresponding times, growth rates are required. Hoof growth rates are known for domestic animals; however, they cannot be obtained easily in wild animals. We estimated the hoof growth rate of the European roe deer (Capreolus capreolus L.) by using the immediate drop in δ13C along the hoof as a tag that is assigned to the date of maize (Zea mays L.) harvest. Keratin samples were taken each mm along 17 hooves and analyzed for their δ13C. A linear regression between (1) time differences of expected maize harvest to animal death and (2) distances between the points of the δ13C drop to the periople yielded the growth rate. Mean hoof growth rate was 0.122 mm/day (95% CI 0.014 mm/day) and 0.365%/day (±0.026%/day) of the hoof length and within the range of domestic animals. The method may be applied to determine growth rates of other incrementally growing tissues. Our estimated growth rate fosters dating isotopic information in hooves, facilitating research on feed resources and space use of roe deer.