Tell-tale testicles: observations of morphological abnormalities in small, spatially restricted mainland quokka (Setonix brachyurus) populations

Abstract

The quokka (Setonix brachyurus) exists in spatially restricted populations in the northern jarrah forest in south-west Western Australia. Observations were made of adult male quokkas exhibiting morphological anomalies (cryptorchidism and micropthalmia) that may be indicative of inbreeding within these populations. Despite the presence of males with abnormalities that could potentially affect their fertility, most females captured were carrying a pouch young or feeding a joey at foot. Field researchers and managers should routinely report abnormalities seen in wild captured animals. Reduced genetic diversity of quokka populations in the northern jarrah forest may not be the key threatening process and preservation of habitat may be more important to ensure persistence of populations. Future management of this species in the northern jarrah forest should include up-to-date occurrence mapping across their range using targeted camera trap surveys and management of habitat to improve connectivity between populations.