ALPHA-MALE SOOTY MANGABEYS DIFFERENTIATE BETWEEN FEMALES FERTILE AND THEIR POSTCONCEPTION MAXIMAL SWELLINGS

Alpha-male sooty mangabeys in four separate social groups discriminate d between a female's fertile and her postconception maximal swelling, confirming a previous finding that one alpha male, but not other males in the group, refrained from mounting females during the postconcepti on maximum swelling. During a 3-hr observation session, the males moun ted females an average of 22 +/- 0.3 times during the females' fertile maximal swelling, while there were no mounts by alpha males during th e females' postconception maximal swelling. Alpha males also showed hi gher durations of following and frequencies of genital inspection towa rd females during the fertile maximal swelling. Additionally, we colle cted blood samples from four females three times per week to monitor e stradiol (E2), progesterone (P4), and luteinizing hormone (LH) changes during both swelling phases. Peak E2 concentrations preceded the maxi mal swelling during both the conception and the postconception swellin g, though to a greater extent during the latter period. Although 3x-we ekly blood samples showed significantly greater E2 concentrations duri ng the postconception swelling, daily samples to confirm the results r evealed one instance of comparable concentrations of E2 during a ferti le swelling. Thus, peak E2 concentrations may not differ during the co nception and postconception swelling cycles, though the duration of th e E2 elevation is longer during the postconception swelling. LH concen trations, corresponding to the conception and postconception maximal s welling, were significantly different, while P4 concentrations were no t. The behavioral results indicate that alpha males discriminate betwe en a fertile swelling (associated with ovulation) and a nonfertile swe lling (occurring approximately 49 days postconception); however, wheth er this discrimination is tied to the difference in the hormonal patte rn has yet to be demonstrated.