Climate‐dependent allocation of resources to secondary sexual traits in red deer

Abstract

Fitness in highly polygynous male ungulates is related both to body size, weight and antler size. Males must therefore allocate resources both to growth of the body and growth of the antlers, which may lead to tradeoffs whenever resource levels are in limited supply. Several studies have reported how (absolute) growth of antlers and horns are related to environmental conditions, but few have looked for the relative allocation patterns (i.e. relative to body size and weight). We analyzed how the influence of variation in climate (the North Atlantic oscillations, NAO) and population density affected the allocation of resources to antlers, based on data from 2720 red deer stags two years or older harvested during 1965–2002 along the west coast of Norway. Number of antler tines increased up to six years of age, remained stable until 12 years of age, and then decreased significantly (>12 years, n=45). The NAO was positively related to number of antler tines in prime aged males (6–12 years, n=629), also after controlling for both body size and weight. Our study thus suggests that deer have a higher allocation of resources to antlers relative to body weight during favorable environmental conditions.