Synchronization of ovarian cycles within and between social groups in golden lion tamarins (Leontopithecus rosalia)

Synchronization of ovarian events has been reported in a number of primate species, with the temporal resolution of synchrony ranging from the occurrence of seasonal breeding within the annual cycle to a close matching of ovarian events within a single ovarian cycle. However, ovarian synchrony has not been reported in a New World primate. The temporal association of ovarian events was examined in female golden lion tamarins (Leontopithecus rosalia) living in the same or different social groups. Ovarian cyclicity was monitored by measuring the excretion of urinary estrogen metabolites. There was a high degree of synchronization in the occurrence of urinary estrogen peaks for females in different social groups (mean peak discrepancy = 2.1 days) and in females housed in the same social group (mean peak discrepancy = 1.3 days). Contrary to previous reports on callitrichid primates, daughters housed in their natal family group exhibited cyclic patterns of urinary estrogen excretion. These findings represent the first explicit demonstration of ovarian synchrony in a New World primate, and the tight coupling of ovarian cycles in female tamarins resembles the nature of menstrual synchrony in human females.