Modelling Koala Populations and Management Strategies
Modelling Koala Populations and Management Strategies
In Australia we have many species that we consider pests. Most people don’t consider the koala (Phascolarctus cinereus) to be one of them. Unfortunately in the late 1800’s and the early 1900’s millions of koalas were killed for their thick reddish brown to grey fur making them extinct in the state of South Australia and endangered across the rest of the country. In a bid to reverse this disturbing trend and conserve this clearly vulnerable animal a group of 18 koalas and a number of young were introduced onto Kangaroo Island in South Australia. These koalas had no natural predators and humans were forbidden from hunting the animals for their fur (Masters etal, 2004).
Unfortunately with none of these pressures that mainland koalas experienced the population quickly rocketed to unsustainable numbers reaching well over 20,000 individuals by 2001. Koalas selective breeding habits have seen significant negative impacts on many habitats that contain their preferred trees. Since 1997 a management program which involves sterilisation of female koalas and translocation of koalas to mainland habitat has been in place to reduce the amount of koalas on the island (Masters etal, 2004).
Unfortunately the number of koalas present on the island was underestimated and therefore management targets were set to low. It is for this reason that we have been employed by the South Australian government to provide an indication of what management is needed to continue to reduce the koala population to a sustainable level. The management strategies available to us as pest management experts are sterilisation of koalas and release back onto the island or translocation of sterilised individuals(Masters etal, 2004).
In order to complete this task and set a management strategy for the area in question we will be using a logistical growth model. This is simply a mathematical model that will provide an indication of the
In Australia we have many species that we consider pests. Most people don’t consider the koala (Phascolarctus cinereus) to be one of them. Unfortunately in the late 1800’s and the early 1900’s millions of koalas were killed for their thick reddish brown to grey fur making them extinct in the state of South Australia and endangered across the rest of the country. In a bid to reverse this disturbing trend and conserve this clearly vulnerable animal a group of 18 koalas and a number of young were introduced onto Kangaroo Island in South Australia. These koalas had no natural predators and humans were forbidden from hunting the animals for their fur (Masters etal, 2004).
Unfortunately with none of these pressures that mainland koalas experienced the population quickly rocketed to unsustainable numbers reaching well over 20,000 individuals by 2001. Koalas selective breeding habits have seen significant negative impacts on many habitats that contain their preferred trees. Since 1997 a management program which involves sterilisation of female koalas and translocation of koalas to mainland habitat has been in place to reduce the amount of koalas on the island (Masters etal, 2004).
Unfortunately the number of koalas present on the island was underestimated and therefore management targets were set to low. It is for this reason that we have been employed by the South Australian government to provide an indication of what management is needed to continue to reduce the koala population to a sustainable level. The management strategies available to us as pest management experts are sterilisation of koalas and release back onto the island or translocation of sterilised individuals(Masters etal, 2004).
In order to complete this task and set a management strategy for the area in question we will be using a logistical growth model. This is simply a mathematical model that will provide an indication of the
References: • ANZECC (1998) National Koala Conservation Strategy. Australian and New Zealand Environment and Conservation Council. http://www.environment.gov.au/biodiversity/publications/koala-strategy/ (accessed 1 May 2008) • Masters, P., T. Duka, S. Berris, and G. Moss. (2004) Koalas on Kangaroo Island: from introduction to pest status in less than a century. Wildlife Research 31, 267–272. • A, Tsoularis; J, Wallace; (2002) Analysis of logistics growth models. Mathematical Biosciences, 1, 27 - 55 •