. Bulletin. Natural history; Science. with several adult males, and almost always becomes pregnant. Although a young male is capable of breeding at the age of two to three years, his horns are still small, and he dares not assert himself against an adult with much larger horns. Horn growth continues throughout life, which may be as long as twenty years. The major horn growth is, however, achieved by the age of seven or eight years. By that time the young adult male is challenging and defeating any older male whose horns do not match his own in size. Amongst sheep at least, older males with sma
. Bulletin. Natural history; Science. with several adult males, and almost always becomes pregnant. Although a young male is capable of breeding at the age of two to three years, his horns are still small, and he dares not assert himself against an adult with much larger horns. Horn growth continues throughout life, which may be as long as twenty years. The major horn growth is, however, achieved by the age of seven or eight years. By that time the young adult male is challenging and defeating any older male whose horns do not match his own in size. Amongst sheep at least, older males with smaller horns are subordinate to younger adults with larger horns; thus neither age nor adulthood is a guarantee of dominance and success in breeding. The evolutionary selection for larger-horned males is balanced in part by the fact that such "successful" males die younger than do smaller-horned adults, who may breed less frequently each season but live to breed over a longer life-span. There is thus a long adolescence for a male ram, almost a third of his life, during which time the females of his age-group are having a lamb each year. The young males, while capable and willing, are not necessary for the immediate reproductive success of the group, but are a kind of insurance, available if by some chance all adult males are killed. We should not over-generalize for the several species of Caprini since prolonged behavioral and demographic studies have been made only on the Alpine ibex (Capra Ibex) and the American bighorn {Ovis canadensis). and some behavioral studies have been made on the Barbary sheep. But for the latter, as for Hemltragus and Pseudois. as well as too often for many species of wild goats and sheep, the published accounts are predominantly those of successful hunters recounting their exploits. This kind of material adds little or nothing to our knowledge of an animal's behavior in infra-group. Male Nubian ibex sparring. Three photos by Uzi Pat. I/C Nat
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Keywords: ., bookcentury1900, booksubjectnaturalhistory, booksubjectscience
