: s s e r t S l a n io it r t u N Why Some Bucks Fail to Reach Their Potential By John Ozoga Photo by Dustin Reid
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hitetail deer exhibit something scientists call sexual dimorphism. That simply means the sexes differ in secondary and primary sexual characteristics. The fact that males grow antlers and females normally don’t is one obvious difference. The sexes also differ in other physiological and behavioral ways. Bucks prefer different habitats, have higher nutritional requirements for growth and have different seasonal fat-storage cycles. They also take longer to attain maximum body size and typically don’t live as long as females.
52 WHITETAIL NEWS
/ Vol. 30, No. 1
When well-nourished, mature bucks are considerably larger than does of similar age. However, as quality of life declines, sex differences in body size diminish, because males tend to suffer more from poor nutrition. Among the many indicators of deer range quality, there is probably none better than the physical size of young male deer. When poorly nourished, autumn-harvested male fawns will be only slightly heavier than female fawns. In fact, on very poor range, that weight relationship between the sexes will also exist among 1-1/2-year-old deer.
Why Bigger is Better Large body size and large antlers tend to go together. Generally, the larger the buck, the larger the antlers. Large, physically superior bucks will dominate others and do most of the breeding. Although seemingly handicapped in winter because of their scant fat stores, the buck’s large body size also contributes to greater metabolic efficiency and ability to withstand greater cold stress. The size of the rumen in relation to body size will determine the quality of forage that can be digested. The larger the body size, the lower the basal metabolic rate per unit of body weight. This difference in body size between males and females lets bucks subsist on lowquality foods when nutritious ones are scarce — a real benefit during winter.
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