SOCIOSEXUAL BEHAVIOR AND THE OVULATORY CYCLE OF PONIES (EQUUS-CABALLUS) OBSERVED IN HAREM GROUPS

Observations of sociosexual behavior of adult ponies, made on 2 harem groups (each comprised of 1 vasectomized male and 3 females), were correlated with follicular development and ovulation for a total of 15 cycles (minimum of 2 cycles/female). Mean cycle length (interovulatory interval) was 19.7 days, with behavioral estrus lasting 7-8 days (5.5 days preovulatory; 2.3 days postovulatory). Estrous females typically showed increased frequencies of approaching and following the stallion, urinating, presenting, clitoral winking and tail raising. Approaching and following the stallion appeared earlier and persisted longer than other estrous responses. Deviations from the modal estrous pattern included cycles with subestrus, continual estrus, behavioral estrus in the absence of ovulation and displays of female mounting. Dominance tests revealed that a mare''s status was unaffected by the phases of the estrous cycle. The presence of more than 1 estrous female affected the copulatory performance of both stallions, most notably in reduced latencies to 1st mount, intromission and ejaculation, in spite of differences between the stallions in sexual vigor. Each stallion usually selected the dominant mare for copulation when there were multiple estrous females present, but mounts were not displayed exclusively to 1 female/test. The social testing situation made apparent the importance of use of space in sociosexual communication in this species, particularly in avoidance of the stallion by diestrous mares and standing alone or in proximity to him by estrous mares.