Observations of interference competition between the introduced black rat and native marsupial gliders in Australia

Introduced rodents, particularly the black rat (Rattus rattus), have caused serious ecological impacts due to their ability to interact with native species as both predators, and by eliciting competitive pressure. However, impacts of black rats upon many Australian mammals have yet to be determined, particularly when those mammals are arboreal. Here, we present novel observations in the form of camera trap footage and photographs of interspecific competition between the introduced black rat and two species of arboreal gliding marsupial (sugar gliders (Petaurus breviceps) and squirrel gliders (Petaurus norfolcensis)) in urban bushland reserves in New South Wales, Australia. Gliders were found to flee or were prevented from exploiting food resources due to antagonistic posturing and physical attacks by black rats. While interspecific aggression and interference competition between black rats and native mammal species has been demonstrated previously, this appears to be the first observation of such interactions for Australian gliders. Our findings may have implications for the future management of glider populations in urban bushland where they co-occur with rats; however, further research needs to be undertaken to determine the extent of this potential threat.