Study of Urinary Estrogens Profile in Captive Female Sloth Bears Melursus ursinus And Influence of Proximity to Other Bear Gender Groups

Abstract

The sloth bear (Melursus ursinus) is one of the four bear species found in India with the widest distribution throughout the country, and is also one of the common bear species housed in the zoos in India. The sloth bear is currently categorised as vulnerable in the IUCN Red List, due to their reducing populations owing to shrinking of habitat, increasing conflict with humans and poaching. It is protected under Schedule I of Wildlife (Protection) Act, 1972 of India. Despite its threatened conservation status and wide distribution, sloth bear is still one of the least studied Ursids. Basic information about their biology and ecology such as reproductive physiology and behaviour, is still largely unknown. newlineIn this study, the estradiol profiling of the female sloth bears was carried out using non-invasive urine samples. Data were collected throughout the study period on the physiological changes in the vulva visibility and the changes in reproductive behaviours, especially during breeding season. The effects of age, estrus duration, and physical and non-physical proximity to males and females on the estradiol levels, vulva visibility changes and exhibition of reproductive behaviors were assessed. newlineIt was found that the general breeding season in sloth bears extended from May to July with the estradiol levels peaking in the month of June. Along with estradiol, the peak vulva visibility as well as the peak exhibition of reproductive behaviours were observed in the month of June. Age of the bear negatively affected the estradiol levels and the exhibition of increased vulva visibility. It did not influence the mounting receptivity, but did have negative effect on the scent-marking indicated by characteristic vulva rubbing behaviour. The changes in the social compositions and physical and non-physical proximity to males and other females had evident effects on the estradiol levels, changes in vulva visibility and the reproductive behaviours. newlineThe outcomes and results from this study provide a framework to sloth bear managers, conservationists and in case of captive facilities, the sloth bear keepers to non-invasively track the estrus status of the females during breeding season and thus prepare the efficient strategies for successful captive breeding programs. newline newline