Social behaviour, population structure and reproductive potential in impala

Summary Impala in southern and eastern Africa differ in the proportion of the year during which adult males are effectively territorial, and consequently in the age at which young males are driven from the female herds. A comparable difference in the age at which male mortality accelerates, relative to female's, suggests that this differential mortality is a product of male‐imposed social organization. In theory this produces enhanced resource flow to females in the population, leading to a greater natality per unit of resource than would be possible without these effects of social organization. It seems that the impala's kind of social organization can not have a density‐dependent regulatory function.