Copulatory Behavior and Reproduction in the Binturong, Arctictis binturong

Abstract

Observations of binturongs (Arctictis binturong) in captivity revealed that copulation was usually arboreal and was characterized by repeated mounts with multiple bouts of intravaginal thrusting. Receptive females showed increased activity, a vaginal mucous discharge, and increased frequency of two vocalizations. Neck-biting was absent, but tail wrapping was unique to the female. Known-aged females first copulated at a mean age of 30.4 months (range = 12.9-47.9), and conceived for the first time at 30.0 months (range = 13-47.9). Males copulated for the first time at 27.7 months (range = 13-45.7). Both sexes can remain fertile until at least 15 years old. The maximum life-time productivity in captivity was estimated to be 23 young. Quantitative reproductive data obtained from a zoo survey revealed that binturongs breed year-round, but show a pronounced birth peak from January through March. Estrous cycles averaged 81.8 days and copulations were seen over a period of 1 to 15 days (X̄ = 6.1), suggesting a long period of estrus. Mean gestation was 91.1 days (range = 84-99), litter size ranged from one to six (X̄ = 1.98), and the sex ratio at birth was not significantly different from 1:1. The prenatal growth rate was approximately 3.5g/foetus/day; neonatal weight ranged from 283.8 to 340.5 g (X̄ = 319), or about 2.9% of the nonpreganant female's weight.