Longitudinal monitoring of fecal testosterone in male Malayan Sun bears (U. malayanus)

Abstract

Fecal steroid monitoring was applied as a non-invasive method to investigate testicular cycles and seasonality in the Malayan Sun bear (Ursus malayanus), an endangered ursid from South East Asia. Fecal testosterone was analyzed by radioimmunoassay in samples collected from male Sun bears (n=8) housed in zoological parks in North America and New Zealand, over periods of 0.05). All bears did, however, share a common pattern of annual excretion that suggests a potential role for non-photoperiodic seasonal influences on testicular cycles. Levels were generally lower early in the year with regular increases occurring at 3–4-month intervals. Grouped data suggest an association between cycles of testosterone production in males and months of peak reproductive activity in captivity. Zoo Biol 0:1–15, 2005. © 2005 Wiley-Liss, Inc.