Associations Between Individuals and Classes in Groups of Different Size in a Population of Western Gray Kangaroos, Macropus-Fuliginosus

Abstract

Associations between different classes of animals, and between individuals, were analysed in a population of 150-170 western grey kangaroos living in a 300-ha remnant of wandoo woodland and adjacent farmland. The commonest group size was one, and 71% of groups were of three or fewer individuals. Females with juveniles at foot were seen in a significantly different distribution of group sizes than females without juveniles, or males. The associations between classes in groups of 2, 3 and 4 changed with the size of group. In groups of two, but not in groups of three and four, males were seen together more frequently than expected. Females without juveniles at foot associated with their peers more frequently than expected in groups of two and three, but those with juveniles at foot associated with their peers less frequently than expected. Other associations between classes were significantly different from expectation. About 70% of the sub-adult and adult animals were individually identifiable by numbered collars. The highest frequency of association of one individual with another was less than 40% of the times the two were seen on the same night. However, nearly all individuals had statistically significant associations with one or more individual in each year, and dissociations with others. The associations did not persist from year to year. The overall group social structure, as shown by single-linkage cluster analysis, was for individuals to associate with others of the same sex, although sub-adults were more generally associated with adult females. The overall level of association was lower in males than in females and juveniles.