Koalas are mammals that are only found in Australia. They look like a small bear with soft thick fur, a large nose, round ears and no tail. Koalas are a grey or brown colour all over except on the belly were it is white. They belong to the Marsupial family. Koalas live in Eucalyptus forests and rely on the forest for food and shelter, consuming about a kilogram of leaves per day. In fact, only a few species of eucalyptus are suitable for food and the koalas need a varied diet from their leaves. Most of the day, the koalas sleep in the fork of a tree. They move about and feed at night though most of their activity takes place just after sunset. Koalas are skillful climbers, getting up tree trunks by clasping them with the sharp claws of their 'hands' and then bringing the hindfeet up together in a bounding movement.When walking on a branch koalas grip with the first toe of the hindfoot and with the first two digits of the 'hand' opposed to the other three. Koalas may also move about covering quite some distances on the ground, bounding along merrily, using the hindlegs in much the same way as they climb or walk quadrupedally.
Koalas do have a tail, but it is so short that it is almost invisable. The pouch of the female encloses only two nipples and opens towards the rear. There is only one pair of lower incisors in the lower jaw and only one well-developed pair in the upper jaw. There are no canines.
Koalas in the forest live a solitary life, with their population well spread out. Breeding occurs in summer; most mature females produce only one young each year. This may weigh less than half a kilogram at birth and will remain in the pouch for seven months. After leaving the pouch, the koalas feed on a mixed diet of milk and leaves, grow fast and travel clinging to their mother's back. They are not fully weaned until they are 12 months old.
There is little reliable information about the lifespan of koalas. However, in captivity they have been observed to reach the age of 15 years.
Koalas were introduced to Kangaroo Island in the 1920's. The habitat was perfect for a Koala population and so they prospered. They were then relocated to other areas on the island, and are now found across much of the island. Today their numbers have increased to such levels that they are unsustainable causing tree loss and the degradation of riverine habitats. The estimated population of koalas on the island is about 3000 to 5000 koalas, with densities of up to 5.5 koalas per hectare.
Unless management strategies are implemented, the welfare of koalas on the island will worsen. It would lead to inhumane suffering of koalas from starvation, reduced health of koala population due to lack of food, continued tree loss and environmental problems.
As koalas were introduced to the island they must be managed with a view to restoring and maintaining the ecosystem's integrity for the sake of the plants and the other animals native to the island. If no action is taken, over browsing by koalas will not only kill the trees but it will also result in food shortage for the koala population leading to food shortages for other animals as well.
Koala numbers on Kangaroo Island have grown to such levels that they threaten the habitat in which the koalas and other animals depend.They are causing over browsing, tree deaths, degradation of riverine habitats and soil erosion.
Without any effective wild life management the koala population will suffer food shortage leading to starvation of koalas as well as other animals. The Department of Environmental and Natural Resources in South Australia have come up with 8 management options, Taking in to consideration
The cost of sustainability and community acceptance also had to be considered.
SolutionsThe option to do nothing does not address the need to protect and restore wildlife habitat. 'Doing nothing' may lead to large scale reduction in koala numbers on the island but it is cause by inevitable starvation and inhumane suffering of many animals. This option does not consider the animal welfare issues and is considered unacceptable.
This option involves protecting existing vegetation and re-establishing trees, shrubs and plants to provide food, shelter, and nesting requirements for native animals. Action would include fencing to promote natural regeneration, direct seeding and planting tubestock. This option does not address the need to reduce the koalas population, but it is useful for a long term strategy for wildlife conservation and therefore benefit the koalas in the future.
Fertility control is a recent concept in wildlife management and involves three main avenues of research:
None of these techniques have been used on koalas as yet.
Fertility control affects future birth rate only. It therefore can not address the immediate need to reduce koala populations on Kangaroo Island. However, once koala populations have reduced to sustainable levels, this option should be useful to maintain these levels
Translocation can be used to relieve overbrowsing at selected sites and re-establish koalas in their former range (ie lower South East). However, overbrowsing may continue on Kangaroo Island and may even become a problem in the release areas. It is therefore important that the extent of suitable habitat available is thoroughly assessed before translocations occur.
Based on information on potential habitat in the lower South East, translocation may provide some immediate relief but would not reduce koala impacts at all severely affected sites on Kangaroo Island and does not address the need to maintain low koala densities over the longterm.
Translocation combined with fertility control is potentially more effective. If translocated animals were unable to reproduce, more animlas could be moved from Kangaroo Island without risking overbrowsing of habitats in the South East.
Deliberate introduction of diseaseKoalas in South Australia are free from "chlamydiosis", a disease which causes chronic urogenital tract infections and conjunctivitis in koala populations in Queensland, New South Wales and parts of Victoria. Females can become infertile and both males and females with servere infections can suffer considerably and die.
Koalas on Kangaroo island have low levels of genetic variation due to the limit number of original stock and may therefore be more susceptible to the disease.
This option is unacceptable on animal welfare grounds.
Captive careKoalas could be caught and passed into zoos and private hands.
This option would not address the immediate need to reduce koala populations on Kangaroo Island as it would only involve a small number of animals. It also raises welfare issues associated with capture and confinement over long periods. However, sale of koala to recognised fauna parks and zoos using established practices to ensure the animals are well cared for could be used to help fund much needed wildlife management research.
CullingCulling is a recognised wildlife management strategy to control aniaml populations where their numbers exceed carrying capacity of the habitat.
Community educationResponses to this issues clearly show that the community has an interest in and commitmenttp conservation and wildlife mangagement. Further information on mangagement options and issues is needed by the community to enable them to take part in an informed debate on how to address this difficult and emotive issue. This option is part of a long term strategy that is valuable in vestment in encouraging wise wildlife management decisions in the future.