Monitoring reproduction in the critically endangered marsupial, Gilbert's potoroo (Potorous gilbertii): Preliminary analysis of faecal oestradiol-17 beta, cortisol and progestagens

Gilbert's potoroo (Potorous gilbertii) was rediscovered in 1994 after having been presumed extinct for 120 years. Estimates indicate fewer than 40 individuals remain at Two Peoples Bay Nature Reserve on the south coast of Western Australia although a translocated population of approximately 20 animals has recently been established on nearby Bald Island. A captive breeding facility has been established adjacent to the mainland population but few young have been produced (8 since 1995). Faecal levels of oestradiol-17 beta (E(2)) were monitored over a 2-year period in an effort to determine cyclic reproductive activity, and faecal cortisol levels were also monitored to gauge whether chronic stress may be a factor limiting breeding in captivity. Faecal steroids were monitored in six captive females, and four captive male potoroos, and four wild females. The only captive births recorded after 1998 were one in August 1999 and one in February 2001, both to the same female. Peaks in E(2) concentration, up to 10 ng g(-1) of dried faecal mass were measured and results to date suggest the main breeding period to be November-December based on elevated E(2) levels at this time. Clear patterns of reproductive activity in the captive females, however, were not evident. Analysis of epithelial cell counts from urinogenital swabs and faecal E(2) and progestagen (PM) levels from a single female kept at the Perth Zoo, suggest that Gilbert's potoroo has an oestrous cycle of approximately 39 days. Faecal cortisol levels in captive females were significantly lower than those in wild-caught individuals and thus there is no indication that elevated cortisol levels per se inhibited reproduction in captive females. (C) 2009 Elsevier Inc. All rights reserved.