Mechanical analysis of bovid horns and cervid antlers: a possible ultimate cause for antler casting

Context Cervids and bovids have antlers and horns respectively, which serve important functions. Bovids horns grow continuously, while almost all cervids cast antlers annually. Aims We compared some measurements of the cervid antlers with the bovid horns to show the possible morphological and mechanical reasons for antler casting. Methods We measured the weight and the length of 59 cervid antlers and 35 bovid horns. Then, we calculated the ratio of antler (or horn) weight to bodyweight, as well as the torque of the antler and horns. We used general linear model to test the difference of these four variables between cervids and bovids. Key results Our results showed that (1) the weight of cervid antlers was significantly higher than that of bovid horns, (2) the ratio of antler (or horn) weight to bodyweight showed no significant difference between cervids and bovids, (3) the distance from the centre of gravity to the base of the antler or horn differed significantly between bovids and cervids, and (4) the torque of cervid antlers was significantly greater than that of bovid horns. Conclusions We assumed that the antlers exert more burden on the head of cervids than do horns on the head of bovids. Antler casting could be the evolutionary strategy of deer to relieve the burden of antlers. Implications Unpacking the burden of antler could be one of the ultimate causes for antler casting in cervids.