The Social Organization Of Koalas
thesis
posted on 2019-02-18, 01:09 authored by Peter John MitchellThe koala (Phascolarctos cinereus) is a marsupial arboreal folivore, able to survive on a diet of eucalypt leaves by having low energy requirements for maintenance, activity and growth. This thesis examined the social organization of koalas, and the constraints imposed on this social organization by their phylogeny and by their dietary and energetic strategies as arboreal folivores.
A population of koalas at Redhill Creek, French Island, Victoria, was studied between November 1982 and November 1985. All trees on the study site were marked and mapped, and all koalas on the site were ear-tagged, and their sex and age recorded. The locations of koalas during systematic searches of the site were recorded, with descriptions of behaviour. Manipulations were carried out to test hypotheses related to dominance among male koalas.
Koalas were removed from the study site in the late 1970's . The population structure during the study reflected the repopulation of the site, beginning with the immigration of animals, mainly young males, which resulted in an initial sex ratio 31:23 and a density of 8.9 animals/ha before the removal of some animals in March 1984. The numbers and age of females increased as a result of their philopatry and longevity. Rates of immigration were highest for 2 to 3 year old males, but most immigrants did not remain on the site, particularly when the population density was high. Rates of death or emigration were also greatest males of 2 to 3 years. Older males were philopatric, and the male population increased in age during the study.
Systematic sampling of koala sightings showed that koalas spent 84 . 9% of their time resting, 11.7% feeding, 2.7% moving and 0 . 6% in interactions with other koalas. Koalas remained in the same tree for long periods; animals were in the same tree for 12.1% of sightings made 24h apart. Koalas were more active at night, and during breeding seasons.[...]
A population of koalas at Redhill Creek, French Island, Victoria, was studied between November 1982 and November 1985. All trees on the study site were marked and mapped, and all koalas on the site were ear-tagged, and their sex and age recorded. The locations of koalas during systematic searches of the site were recorded, with descriptions of behaviour. Manipulations were carried out to test hypotheses related to dominance among male koalas.
Koalas were removed from the study site in the late 1970's . The population structure during the study reflected the repopulation of the site, beginning with the immigration of animals, mainly young males, which resulted in an initial sex ratio 31:23 and a density of 8.9 animals/ha before the removal of some animals in March 1984. The numbers and age of females increased as a result of their philopatry and longevity. Rates of immigration were highest for 2 to 3 year old males, but most immigrants did not remain on the site, particularly when the population density was high. Rates of death or emigration were also greatest males of 2 to 3 years. Older males were philopatric, and the male population increased in age during the study.
Systematic sampling of koala sightings showed that koalas spent 84 . 9% of their time resting, 11.7% feeding, 2.7% moving and 0 . 6% in interactions with other koalas. Koalas remained in the same tree for long periods; animals were in the same tree for 12.1% of sightings made 24h apart. Koalas were more active at night, and during breeding seasons.[...]
