PERSPECTIVE ON THE MANAGEMENT OF ISOLATED/ISLAND KOALA POPULATIONS
Presented at the Australian Veterinary Association Conference in Perth
DEBORAH TABART, EXECUTIVE DIRECTOR
AUSTRALIAN KOALA FOUNDATION
"The translocation programs operating in southeastern Australia have established a rare series of wild koala populations that have undergone sequential founding events. Genetic analysis has shown a cumulative increase in inbreeding, and a loss of genetic variation in these populations."
Houlden goes on to say "Inbreeding results in a loss of fertility, reproductive success and survivorship (known as inbreeding depression) in many plants and animals. Inbreeding could ultimately pose a serious threat to the long-term survival of the koala. Preliminary studies have shown that morphological abnormalities including unilateral and bilateral testicular abnormalities and other defects are prevalent in populations in southeastern Australia (up to 30% in some populations). These physical abnormalities may be a consequence of inbreeding in koalas."
"We have assessed the consequences of inbreeding in koalas by quantifying reproductive parameters in populations with a range of bottleneck histories, levels of genetic variation and inbreeding coefficients, to determine whether these variables are correlated."
"Koalas are at an ideal point for intervention, as many of these issues could be addressed by management strategies, including the introduction of unrelated stock (or semen) into island populations." (Houlden et al, 1999)
"On the 6th November, I received into my shelter a male koala, approximately 12 months old, vasectomised, without an ear tag, weight being 1.5 kg - found at ....(a) camping ground. His condition was extremely poor, obviously starved, dehydrated (sunken eyes and no elasticity in skin) and showing signs of pneumonia. He died 7 November. The Autopsy revealed pneumonia and emphysema.
Since then I have admitted to this shelter three koalas - tag number 243 - vasectomised male, dehydrated and thin - Ear tag number 143...comatose, dehydrated, thin. Tag 206 - female, dehydrated and thin, arrived comatose, consequently all have died. Tags 137 and 84 both taken from dead koalas are in my possession - both of these koalas were debilitated, thin, dehydrated, starving/malnourished....One that survived for ten days went trough a toxic stage. Interesting to note that none of the stitches where they had been sterilized had dissolved. I now have tags 241, 218, 245, 256, 117 - all these animals are now dead. Koala 141 is still in the camping ground but unhealthy."