Possums & trees

Possums general

Many Australians share their homes and landscapes with possums because like people, possums are well suited to living in the suburbs. However, at times this contact can be noisy and messy – particularly if the possum takes up residence in the roof of your house or over-grazes a prized plant in the garden.
The most familiar and abundant of the many Australian possum species are the Brushtail possum (Trichosurus vulpecula) and the Common Ringtail possum (Pseudocheirus peregrinus). Depending on where you live, possums along with most native animals, are protected species. Consequently we have to learn to live with possums and manage their behaviour in order to minimise the negative aspects possums can on our properties.
Possums eat the leaves, flowers and fruits of a wide variety of native and exotic trees and shrubs. The Common Brushtail Possum may also eat grass, fungi, bird’s eggs and baby birds. Possums should not be fed human food as it can be dangerous to possums and cause serious dietary imbalance.

How far can a possum jump?

The bushy-tailed Brushtails are agile climbers and are able to leap significant distances as they traverse the urban forest. The distance they can jump is dependent on their take-off platform, whether they can get a run-up to it and also how far vertically they need to jump. The more vertical the distance they have to cover, the shorter the distance they can leap (Cavanagh, 2007).
An agile (young) possum can leap from a fixed, solid base, up to 2.5m horizontally or downwards, around 1.2m at an angle of nearly 50º to the horizontal (close to optimum of 45º) and with a run-up, 1.7 m upwards at an angle of around 18º. Vertical jumping appears to be less than 1m (Cavanagh, 2007).

Control measures

In the event that a tree is showing signs of excessive damage from possum grazing, the tree should be inspected and a suitable course of action determined to reduce further grazing. Listed below are appropriate actions to limit possum access to trees.

• Surveys could be conducted to determine the size of the possum population, the number of dens, whether the possums are local or live in properties surrounding the property, and access to artificial food sources, such as unsecured rubbish bins, food scraps or deliberate feeding.
• Installation of possum guards or bands around the trunks or major branches of the tree. These guards are typically constructed from sheet metal or clear polycarbonate and should be a minimum of 60cm wide. New products like Tree Logic Skin have been designed to provide more aesthetically pleasing possum guards. Where possible the guard will be placed above the first fork of the tree to provide refuge for possums if pursued by other animals, provided that it is not possible for the possum to access the remainder of the tree.
• Possum guards may also be placed on surrounding trees to restrict access to a combined tree canopy.
• The effected tree and surrounding trees may be pruned to reduce the crown away from structures or other trees, to prevent the development of ‘possum highways’. A clear distance of 2m should be created between the tree/s and surrounding structures.
• The ability to limit den sites in buildings and trees should be investigated. Tree hollows should not be filled as this can cause more damage to the tree.
• Strategies could be investigated for limiting possum movement along utility lines.
  Seasonal use of repellents to protect specific vegetation. Possum repellents may work through two chemical senses: smell and taste. Many substances have been used in the hope that they will stop possums eating garden plants. However, the Department of Sustainability and Environment (2007) is not aware of any definitively successful, universal repellent that will consistently deter possums from eating plants. The results of a Deakin University study (Cooney, 1998) suggested that five of the tested compounds may show some degree of repellence. These were:White King®, Keep Off®, Camphor, Naphthalene and Scat®. The other products tested in the olfactory trials were: D-Ter®, Stay Off®, Blood and Bone, Garlic and Quassia chips. Some systemic insecticides used on trees to control sap sucking and leaf grazing insects may also deter possum grazing.

Trapping and relocation may not be viable options. Studies undertaken by Deakin University (Pietsch, 1994) strongly indicate that relocation is not a humane way of dealing with the problem. If a possum is trapped and removed from the ceiling cavity it must be released back onto your property, as it will not survive if removed from the area. In some areas, wildlife rehabilitation groups will help you with this. Block all access points into the roof cavity and install nest boxes in trees to provide alternative nest sites for possums.
Check with authorities in each State or territory for possum protection and control measures:
New South Wales – National Parks:

Northern Territory – Natural Resources, Environment and The Arts

Queensland – Environmental Protection Agency/Queensland Parks and Wildlife Service

Victoria – Department of Sustainability and Environment

South Australia – Department of Environment and Heritage

Tasmania – Parks and Wildlife Service

Western Australia – Department of Environment and Conservation, Nature Base

References
Cavanagh, T. pers comm. 2007
Cooney, J. 1998. An evaluation of commonly used deterrents for urban Common Brushtail Possums Trichosurus vulpecula (Kerr, 1792). BSc (Hons) Thesis, School of Ecology and Environment, Deakin University.
Pietsch, R.S. 1994. The fate of urban Common Brushtail Possums translocated to sclerophyll forest. in Serena, M. (ed.) Reintroduction biology of Australian and New Zealand Fauna. Surrey Beatty & Sons, Chipping Norton.
Possums, 2007 Department of Sustainability and Environment, viewed 13/11/2007

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