Understanding the stress responses of the Koala Phascolarctos cinereus using non-invasive endocrine technology – a collaborative EFC and Dreamworld Australia Project
By: A. Prof Jean-Marc Hero and Dr Edward Narayan
Koalas (Phascolarctos cinereus), Australia’s unique marsupials, belong to the family Phascolarctidae, order Diprotodontia. They are the only extant representatives of the family Phascolartidae. Koalas are listed by the IUCN as a vulnerable species (even considered rare in New South Wales and South Australia). Causes of mortality are diverse, although disease (essentially chlamydiosis), collisions with cars and loss of habitat represent the principal reasons for the species continuous decrease.
Among various conservation approaches, conservation centers have been created that aim at simultaneously protecting the koala habitat, and instructing the public about Koala conservation such as Dreamworld Koala Breeding Facility. Due to their popularity, koalas are a good educational tool for increasing public awareness of conservation for both young and adults. Koalas at Dreamworld can be ambassadors for conservation, particularly as the major factors affecting the long-term survival of wild Koalas, and many other species, is the availability of suitable habitat. Furthermore, research within zoos can contribute to conservation of the Koala through an increased understanding of animal behaviour, reproduction, physiology, nutrition and disease.
Ultimately, this research will enable stress hormones to be measured non-invasively in Koalas and the measurements can inform on animal welfare and thus the suitability of captive environments.
Photography: Dr Edward Narayan
Unfortunately, there are no published data on faecal cortisol concentrations in captive and wild Koalas. While blood glucocorticoid concentrations are acceptedindices of stress, their usefulness in long-term studies with intractablewildlife species is limited due to the circadian rhythmand pulsatile nature of glucocorticoid secretion and the possible induction of a stress responseduring sampling procedures. Conversely, the excretion of metabolized blood steroidsinto faeces permitsthe monitoring of physiological functions without disturbanceto animal subjects.
Overall, the ability to track adrenal activity is essential for understanding the fundamentals of stress physiology. Fecal glucocorticoid metabolite monitoring are now well-established tools for evaluating stress responses in diverse vertebrate species. Because of its enormous utility and non-invasive nature, excreted hormone metabolite monitoring has become one of the most powerful tools available in wildlife research today.
A team of enthusiastic scientists from the Environmental Futures Centre, Griffith University, led by Associate Professor Jean-Marc Hero and Research Fellow Dr. Edward Narayan are aiming to develop non-invasive monitoring of the stress hormones to track the physiological responses of Koalas to routine husbandry in order to improve captive management and breeding. Faecal sampling has already been completed in adult male and adult female Koalas at Dreamworld with help from the Koala keepers and student volunteers from Griffith University. Faecal samples are currently being grinded and extracted at the EFC for stress hormonal assays later this year. Ultimately, this research will enable stress hormones to be measured non-invasively in Koalas and the measurements can inform on animal welfare and thus the suitability of captive environments.