Scent marking koala

Adult male koalas scent mark with their chest gland and often they place their secretion, as shown in Figure 1, on the base of trees before they climb up the tree trunk. During this procedure, the chest is flattened against the trunk and rubbed up and down about six times (Smith, 1980). This behaviour is probably involved in the spatial separation of mature males and in their competition for mates (Martin Lee, 1984 Lee Martin, 1988). 

Smith, M.T.A. 1980. Behaviour of the Koala, Phascolarctos cinereus (Goldfuss), in captivity. IV. Scent-Marking. 

In a recent study of scent-marking behavior in the koala, cinereus (Thompson and Fadem, unpublished observations) a conspicuous sternal gland, seen only in adult males, was used in chest-marking (Fig, 4), In chest-marking, the male koala stood upright, lowered its forelimbs to the side, placed the gland over the area to be marked, and flexed and extended... 

Chest-marking in the koala occurred primarily upon introduction to an unfamiliar tree and declined thereafter. Females rarely chest-marked (only one chest mark was seen in over 20 15-min trials), and highest levels of chest-marking behavior were seen in males 5-10 years old males 1-2 years old marked less frequently (Fig. 5). This is probably related to the fact that puberty occurs at between 1 and 3 years of age and the sternal gland first appears at about 1 year of age in this species (Thompson, personal communication). Thus, age, sex, and time-related aspects of scent-marking in the koala were remarkably similar to those seen in the gray opossum (c.f.. Fig. 1). 

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