Survival, Age-Determination and Population Age Structure of the Common Ringtail Possum, Pseudocheirus-Peregrinus, in a Eucalyptus Woodland and a Leptospermum Thicket in Southern Victoria

Juvenile ringtail possums in two populations were aged by comparison with growth curves based on head length and body weight, and adults were aged by comparing the degree of tooth wear with that of ringtails of known age. Survival to the end of pouch life, 3 months old, appeared high but dropped markedly thereafter. During years of 'average' rainfall, 26-80% of all offspring lived to the age of weaning (6 months), but as few as 6% survived to weaning in a year of drought. Approximately 30% survived to sexual maturity (1 year) during years of 'average' rainfall, compared with 2% during a drought. Survival of adult females was higher than that of adult males, and ringtails at Sandy Point (Leptospermum thicket) appeared to survive longer than ringtails at Lysterfield (Eucalyptus woodland). The lower survival of adult ringtails at Lysterfield was associated with higher rates of tooth wear, possibly due to their more abrasive diet, but may have also been influenced by the hotter climate at Lysterfield. The lower survival of ringtails at Lysterfield resulted in a population with a greater proportion of 1-year-old animals than in the Sandy Point population.