By their third year, hinds approach their asymptotic weight of over 300 kg. Conceptus weights and milk production increase markedly from first to second parities and slightly with age thereafter. During winter, free-ranging animals lose weight in the face of declining quality and availability of native forage. The impact in both absolute and relative terms is greatest for larger individuals. Weight loss occurs mainly in late winter as snow deepens and forage quality declines to critical levels.
Spring comes abruptly and weights, particularly of pregnant females, increase rapidly.
Even at peak lactation, weight gains are positive and small females are able to narrow the contrast in weight with large females over the summer. Weights of reproductive and non reproductive hinds on lightly supplemented pasture illustrating the demands of gestation and lactation. In reproductive adult females, rumen-fill threatens to constrain intake only in autumn. Particularly in large individuals, weight loss appears to be due to the logistic constraint operating in late winter. With snowmelt, intake increases rapidly in compensation.