Information content of sexual swellings and fecal steroids in sooty mangabeys (Cercocebus torquatus atys).

The accuracy and precision of sexual swellings and fecal steroids as measures of ovarian function and the periovulatory period were compared in 4 sexually mature, individually housed, sooty mangabey females. Fecal samples were collected daily over a 10-week period during the normal breeding season. Serum was collected 3×/week, daily during peak swelling, and sex skin was rated 5×/week on a 0-5 relative scale. Both fecal estradiol (fE2) and progesterone (fP4) were significantly correlated with serum values in composite E2-aligned profiles and within the cycles of individual females with average correlations of rs = 0.6. Follicular phase means for fE2 and luteal phase means for fP4 were significantly correlated with the serum means across cycles, suggesting that fecal concentrations could be used to accurately evaluate cycle phases within and across females. In contrast, the timing of peak swelling relative to the periovulatory period varied considerably across the cycles of individual females. Although maximum tumescence appears to bracket the periovulatory period, individual differences in the duration of peak swelling and the timing of its onset and end tend to obscure the exact time of ovulation in relation to maximal tumescence. These data illustrate the utility of fecal steroid analysis as a tool for further evaluation of the signal value of sexual skin and its role in mating interactions. © 1996 Wiley-Liss, Inc.