Long-term data on basic reproductive parameters and evaluation of endocrine, morphological, and behavioral measures for monitoring reproductive status in a group of semifree-ranging Tonkean macaques (Macaca tonkeana)

Abstract

Cycle and gestation lengths, menstruation patterns, female genital swelling characteristics, and male-female consortship durations are reported in a semifree-ranging group of Tonkean macaques (Macaca tonkeana) studied over a 12 year period. In addition, profiles of urinary estrone conjugates (E1C) and immunoreactive pregnanediol glucuronide (PdG) throughout four complete menstrual cycles in two females and three full-term pregnancies are presented. Based on intermenstrual intervals, a mean cycle length of 37-41 days (n = 55 cycles in 10 females) was found. Gestation length averaged 173 days (n = 27 pregnancies in eight females). Measurement of PdG immunoreactivity in urine revealed a cyclic pattern with a 5-15-fold increase between follicular and luteal phase concentrations, suggesting that PdG is a reliable indicator of ovarian cyclicity and luteal function. In contrast to PdG, E1C excretion showed no clear pattern throughout the cycle; however, highest values of E1C were usually found shortly before the onset of the luteal phase PdG rise at the presumed time of ovulation. Levels of both hormones were elevated during the first half of gestation and showed a marked increase throughout the second half, with maximum E1C concentrations being up to 100-fold higher than nonpregnant levels. Consortships by the male and occurrence of female genital swelling were long lasting (on average 5-10 days and 13 days, respectively) and were restricted to the follicular phase of the cycle. The day of maximal swelling and day of detumescence as well as the end of male consortship were closely associated with the periovulatory period. Swellings and consortships were longer following lactational ammenorhea than for subsequent cycles. The evolutionary significance of the cyclical changes undergone by females upon their relations with males is discussed. © 1996 Wiley-Liss, Inc.

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