Fecal steroid analysis for monitoring reproduction in the sun bear ( Helarctos malayanus)

Abstract

Fecal steroid analyses were conducted on captive ( n=10) and free-ranging ( n=2) sun bears ( Helarctos malayanus) in order to establish a noninvasive technique for monitoring endocrine profiles during the estrous cycle and pregnancy. Secondly, the effect of the contraceptive porcine zona pellucida protein (PZP) on reproductive function was studied. Finally, we investigated whether the sun bear, naturally living in the aseasonal tropical forests of Southeast Asia, is a seasonal breeder. Fecal samples were collected over periods of 7–48 months in captive untreated ( n=8) and PZP-treated ( n=2) female sun bears. In addition samples were collected over a period of 12 months from radio-collared free-ranging females ( n=2) in their natural habitat in Indonesian Borneo. Androgens, precursors of estrogens, were found to be reliable indicators of the follicular phase, whereas estrogens were found unsuitable. Pregnanediol assay was found to be a reliable indicator of luteal function. Results indicate that sun bears are polyestrous, nonseasonal breeders. Interestrus intervals in nonpregnant animals ( n=2), which were monitored for 27 months, were between 140 and 216 days. Luteal phases (89.6±3.7 days; n=9) were preceded by androgen peaks of 15.2±1.0 days ( n=10). Hormonal profiles of two females treated with PZP indicated missing ovarian activity in one, and persistent follicular and luteal activity in another animal. However, extended periods of missing ovarian, and persistent follicular and luteal activity were also observed in other sun bears studied.