Factors influencing cyclicity and reproductive success of female elephants in European zoos

Abstract

The capture of wild elephants is prohibited under the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES). However, since elephants (particularly Asian elephants) are endangered in the wild, maintenance of a healthy captive population is considered an essential measure for safeguarding the species; in turn, an active and successful breeding program is an essential requirement for maintaining a healthy captive population (Hermes et al, 2004). Recent surveys have indicated that captive elephants commonly suffer from poor fertility as a result of intermittent cyclicity or acyclicity among female elephants, and as a result of high rates of perinatal and infant mortality (Freeman et al, 2009).

The aim of the current study was to retrospectively examine the incidences of gestational and perinatal mortality and of disrupted cyclicity in elephants housed in European zoos and to try to identify husbandry or management associated risk factors that predispose to either failure of cyclicity or failure to produce a live calf. In order to gather the required data a questionnaire was sent out to all European zoos that house elephants and progesterone/pregnanetriol concentrations were gathered when made available.

Fifteen zoos completed the questionnaire, yielding a survey population of 50 elephants. Reproductive status monitoring data (progesterone/pregnanetriol profiles) were available for only 18 elephants. Since there were only 2 elephants that showed abnormal cyclicity, it was not possible to further examine factors that might influence cyclicity in captive female elephants. A significant difference (p<0.05) was found in the successful completion of pregnancy between Asian and African elephants. Asian elephants suffered a significantly higher risk of abortion, stillbirth or death of the calf within the first day after birth. There was also a significant lower likelihood (p<0.05) of the first (as opposed to subsequent) pregnancy of an Asian elephants in captivity leading to a surviving calf.