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Observations of male-on-male agression among Queensland koalas (Pascolarctos Cinereus) from Central Queensland.

A. Melzer

W.A. Ellis

F. Bercovitch

Koala Research Centre of Central Queensland, CQUniversity, Rockhampton, Qld 4702.

San Diego Zoo’s Institute for Conservation Research, Zoological Society of San Diego, 15600 San Pasqual Valley Road, Escondido, CA, USA 92027. 

Primate Research Institute & Wildlife Research Centre, Kyoto University Inuyama, Aichi, 484-8506 Japan 



Agonistic behaviour (Scott and Fredericson 1951) includes behaviour related to attack, fight, defence, flight or submission. Such behaviour among macropods has been well studied (e.g. Glanslosser 1989) probably because such behaviour is overt and relatively easily observed. In contrast, the predominantly arboreal and largely nocturnal activity of koalas makes behavioural studies difficult. Given that koalas are only active for about 1 to 4 hours every 24 hour period (Martin and Handasyde, 1999), the probability of observing any type of social behaviour is quite small.

Koalas are considered to be solitary animals (Martin and Handasyde 1999). Males, in particular are considered to be highly territorial and to expend a considerable amount of energy in interacting with other males (Martin and Handasyde 1999). The most systematic studies of male-male aggression have been pursued by Smith (1980a, 1980b), observing captive animals, and Mitchell (1990), studying wild southern koalas (Phascolarctos cinereus) at Redbill Creek, French Island, Victoria. Most importantly Smith categorised the vocalisations associated with antagonistic behaviour while Mitchell categorised behavioural patterns associated with malemale aggressive behaviour. These provide a systematic approach to the description of observed wild encounters. Mitchell (1990) records 169 cases of male-male interaction. However, Mitchell manipulated some encounters by introducing males to trees occupied by other male koalas. These, modified from Mitchell (1990) included: (1) attack/chase interactions that encompassed:  Attack-flee described as short, violent interactions;  Chase-flee where the chasing male does not make contact with the other animal,  Attack-rapid retreat where the retreating animal reaches the end of a branch before the attacking animal can catch it and the attacking animal does not follow the retreating animal to the end of the branch