By

 Melissa Griffiths

At this year's Veterinary Conservation Biology and Wildlife Health and Management Conference, held at Sydney’s Taronga Zoo in early July, speakers from around the world presented seminars on topics including the causes for declining frog populations, the control of feral animals, harvesting kangaroos, and other methods of improving the sustainability and survival of Australian wildlife.

Peter Brown from Deakin University in Melbourne presented an in-depth discussion on wildlife rehabilitation and relocation in Australia.     This topic has proven to be controversial one, with many animal welfare organisations disagreeing with the strategies behind rehabilitation and translocation of native Australian animals, mainly because of the many problems affiliated with long-term survival of the animals.     Yet thousands of people throughout Australia are involved in wildlife groups, therefore the motivations behind wildlife recovery programs stem from good intentions, which in turn inspire educational and conservation activities.

Across Australia, interaction between people and wildlife in urban environments continues to increase.     As human populations grow and expand into surrounding bushland on the urban fringe, native flora and fauna adapt to new habitats provided by urbanisation.     There are many positive outcomes associated with wildlife and human relationships, including tree-planting days, the construction of nest boxes for birds and possums, the provision of food for wildlife, and rescue organisations such as the Wildlife Information and Rescue Service (WIRES).     However, animals are also at risk from human intervention.

According to Brown, vehicle accidents, attacks by dogs and cats, collisions with human-made objects, poisoning, contamination, trapping and shooting are the main causes of wildlife injury and death within Australia.     The majority of these incidents involves birds and mammals (possums and Eastern Grey Kangaroos).     When an injured or orphaned animal is admitted to a shelter, the length of stay depends upon the severity of its injuries and its speed of recovery.     Lengthy periods in captivity may have important implications for the long-term survival of these animals upon release.     Brown's study indicates that wild caught animals have a higher chance of survival once relocated than do animals born in captivity.

Problems Associated With Relocation

The long-term survival of animals released back into the wild by carers is largely unknown¹.     A significant proportion (about 14 per cent) of captured injured wildlife die in captivity after five days due to stress.     A number of studies on common brushtail possums (Trichosurus vulpecula) and the common ringtail possums (Pseudocheirus peregrinus) found that most relocated (i.e., animals released back into the wild after rehabilitation), die soon after release¹.

The problems associated with relocating animals after rehabilitation vary according to the seriousness of injury, length of time spent in captivity and rehabilitation techniques.     Most problems arise from the amount stress endured by the animal, along with poor evaluation by carers of the relocation site.     For example, the relocation site may be already overpopulated and exceeding its carrying capacity or the amount of resources available to sustain existing populations. Releasing individuals into an already stressed site may push the site above its carrying capacity, which inevitably will cause a decline in population numbers until equilibrium is reached.

Genetic problems and disease are other factors associated with relocation.     If the re-released animals survive, they have the potential to breed and hybridise, and this can result in a population less well adapted to the environment¹.

Lack of survival skills is another common cause of death after relocation.     An animal spending a considerable time in captivity, especially a young animal, may not develop the essential survival skills required once relocated. Social skills and reproductive skills may diminish within captivity, along with the ability to recognise and avoid predators, causing the animal to be more susceptible to attack.    But such detrimental results may not necessarily be true for all species in all circumstance, and further research is clearly needed to determine the factors important to release success.

Benefits Associated With Relocation

Research into release techniques and the fates of released animals may not only lead to greater survival of rehabilitated wildlife, but may also help in the development of improved release protocols for threatened species translocations ¹.     Improved rehabilitation and release strategies employed by wildlife groups, along with additional research into post-released animals, the impact on resident populations, and promotion of continuing education, may make wildlife rehabilitation and release a desirable and effective part of wildlife conservation.

Melissa Griffiths is the Editorial Assistant for Today's Life Science, Lab News and LifeScience.com.au

Reference

¹ Tribe, Andrew and Brown, Peter (2000). “Well it sounded like a great idea at the time”: wildlife rehabilitation and relocation in Australia. Aussieprint, Australia.

This article was first published in ‘The Veterinarian’ in September 2001 and is reproduced with sincere thanks and appreciation to the Editor of that paper and to the Author.