, Volume 12, Issue 1, pp 1–31

Estrous behavior of free-ranging rhesus monkeys (Macaca mulatta)

  • James Loy


The sexual behavior of a group of free-ranging rhesus monkeys (Macaca mulatta) was studied for 13 consecutive months in an attempt to determine whether or not sexual activity occurred year-round, and the importance of sexual attraction to rhesus monkey social organization.

Estrous behavior was seen both inter-menstrually and peri-menstrually, producing a shorter mean estrous cycle length than reported by other workers. New data was gathered on the interrelationships among age, dominance rank, and sexual activity; son-mother and brothersister matings; and sexual favoritism among free-ranging rhesus monkeys.

A few females who failed to conceive during the fall breeding season showed cyclic estrous behavior throughout the entire annual cycle. Hypotheses are given as to possible physiological bases for birth season sexual cycles.

Several forms of inter-animal bonding, including sexual bonding, are enumerated, and their importance to rhesus monkey social organization discussed.


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Copyright information

© Japan Monkey Centre 1971

Authors and Affiliations

  • James Loy
    • 1
  1. 1.Northwestern UniversityKnoxvilleUSA
  2. 2.Department of AnthropologyNorthwestern UniversityUSA

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