Abstract
Influence of a mother's dominance rank and her yearling's sex on the onset of the next reproductional cycle was studied in a free-ranging troop of Japanese macaques at Jigokudani Monkey Park, the Shiga Heights, Nagano Prefecture, Japan. Yearlings of lower ranking mothers were harassed more frequently by unrelated animals. No difference in the frequency of social interactions between a mother and her yearling was noted with regards to dominance rank or the offspring's sex. However, the onset of estrus in higher ranking mothers was earlier in the subsequent mating season. The present study suggests that local resource competition is not intense and aggression toward yearling macaques by unrelated animals does not affect interactions between a mother and her yearling. It is hypothesized that because higher ranking mothers were in good condition nutritionally, they exhibited estrus earlier.
