Social affiliation among sub-adult male koalas in a high-density population

Koalas are generally considered to be a solitary species. However, during observations of free-ranging koalas in a high-density population, sub-adult males (3.5–5.5 years) were seen engaging in affiliative behaviours, including grooming, genital sniffing, and vocalising. These interactions were exclusive to males of this age group and are likely a result of the unusually high population density. In such populations, where home range overlap is common, these behaviours may help reduce stress, establish dominance hierarchies, and reduce conflict through familiarisation.