Population management and bone structural effects in composition and radio-opacity of Iberian red deer (<Emphasis Type="Italic">Cervus elaphus hispanicus</Emphasis>) antlers

Antlers are costly bone structures whose size and external characteristics are influenced by nutrition, climatic variability, and other factors. In this study, we examined the effects of a well-managed captive population vs unmanaged free-ranging herds (greatly differing in food availability and energetic and immunological expenditures) on antler structural characteristics of Iberian red deer. We assessed the effect of management and sample position in the antler on cortical bone depth, bone mineral and protein content, and radiographic bone opacity. Cortical bone depth and mineral percent was greater in captive animals on greater food availability and lower energetic and immunological expenditures. After removing the inverse relationship with mineral content in the model, protein percent was also higher in antlers from captive than in those from free-ranging deer. Management system also influenced radio-opacity indirectly as interaction with other factors and cortical bone depth effects. Structural properties also differed between antler points that are very close in the antler and seem to differ only in the role they play. In conclusion, captive management can affect antler structure and composition, possibly as a result of different availability of food and immunological costs.