The effect of animal density on metacarpus development in captive fallow deer

During the development of mammals, skeletal growth is an informative measure of homeostasis between environmental conditions and individual anabolism. Young animals are more sensitive to adverse conditions than adults because they invest the majority of their resources in somatic growth. Here, by means of a manipulative experience, we aim to explore the effect of density oscillations on skeletal development as measured by the age of ossification and the total length of the metacarpus in juvenile fallow deer (Dama dama Linneaus, 1758) inhabiting an enclosure (south-western France). Our results show that, for animals born at high density, the total length of the metacarpus was lower on average by about 11.2 mm for females and 9 mm for males compared to animals born in low-density conditions. Furthermore, we observed that the age of ossification of both sexes was earlier in animals that experienced high density during early growth (5.8 months for females and 7.7 months for males at high density versus 12 and 12.8 months, respectively at low density). The total length of metacarpi and the age of ossification did not differ between the sexes in both high- and low-density periods. We conclude that the length of bones and the age at which animals achieve total ossification is sensitive to changes in animal's density, probably because of density-dependent competition for resources.