PECULIAR ANTLER CAST BY MOOSE ON THE COPPER RIVER DELTA, ALASKA

Abstract

Forty percent of cast moose (Alces alces gigas) antlers (n = 25) collected from the west Copper River Delta, Alaska had from 2.0-7.6 cm of assumed pedicle bone beyond the normal abscission point at the coronet. We examined the hypothesis that high levels of iron (Fe) in aquatic plants eaten by moose formed an insoluble complex with phosphorous (P), resulting in weak pedicles. Significant differences (MANOVA F_6,42 = 2.53, P = 0.035) among antler samples were due to greater concentrations of P and Fe in pedicle samples than in shaft material of antlers with or without extra pedicle. Calcium:P ratios were equal for all sampled. However, the P:Fe ratio was smaller for pedicle material than shaft material from both antler types, but the pedicle material was composed entirely of cancellous bone. Our results confirmed the assumption than an extreme amount of pedicle material was being cast in some antlers. Mineral imbalances associated with aquatic foraging may be responsible for this unusual antler casting. However, alternative explanations include a genetic or hormonal anomaly, as well as an extreme convex seal in prime animals in high quality habitat. Examination of these alternatives leads to the conclusion that the ultimate factor is genetic, but the actual physiological mechanism producing the abnormal antlers is unknown.