Body Mass Dynamics of Moose Calves in Relation to Winter Severity

We measured winter and spring loss of body mass among moose (Alces alces) calves in a population in southcentral Sweden (Grimso). The sample consisted of 522 calves of both sexes killed during October-May from 1973 to 1988. Males were consistently heavier than females (P<0.05). Body masses of moose calves were significantly associated with both winter severity (P<0.05) and the date of kill (P<0.001). Mean loss of body mass was highest in hard winters (13% from Nov to Feb-Mar). Conversely, average net gain in body mass from autumn (Nov) to spring (Apr-May) (20%) was highest in mild winters. Snow depth, but not temperature and precipitation, was significantly associated with loss of body masses during winter (P<0.02). During winter, small calves lost not only a larger proportion of their body mass, but also more kilograms than large calves