The Common Brushtail Possum (Trichosurus vulpecula, from the Greek for
"furry tailed" and the Latin for "little fox") is the largest possum, and the Australian marsupial most
often seen by city-dwellers, since it is one the very few that thrives in cities as well as a wide range of natural and
human-modified environments. Despite its resemblance to a fox's brush, the characteristic tail is prehensile and is naked on its lower underside.
Like most possums, the Common Brushtail is nocturnal. It is mainly a folivore, but supplements its usual diet of leaves with fruit, invertebrates, flowers, buds, and whatever else
is available. In most Australian habitats, leaves of Eucalyptus are a significant part of the diet but rarely the sole item
eaten. This is probably because of the tannins and other chemical defences present in eucalypt leaves. Around human habitations,
Common Brushtails are inventive and determined foragers with a liking for fruit trees, vegetable gardens, and kitchen raids.
Brushtail Possum in Brisbane, Queensland, Australia
Brushtail Possum in Sydney, New South Wales, Australia
They are highly inquisitive and live in troupes of about a dozen individuals with a complex social structure not dissimilar
from wolves and primates.
During the day, Common Brushtails sleep in a den in a hollow tree or any other convenient place, notably ceiling spaces that
are not securely sealed. Although primarily arboreal and not found in places without trees to provide refuge, they spend a good
deal of time on the ground. They are able to stand upright.
The very loud hissing, crackling territorial call of the male Common Brushtail has a harsh quality. They have a number of
other vocalizations, mainly consisting of pitched clicks. Most are also relatively quiet. Socially they may be solitary or they
may form small groups which share territory.
Keeping of Brushtail Possums is prohibited in many areas, and they do not make good pets. If hand reared they will become tame to
humans, but still keep an instinctive urge to explore their surrounding area which can bring them into contact with a number of
threats. Not the least of which is the wild possums in the area which will be highly territorial and aggressive to any new
possum. Feeding of hand reared possums is also involved, after weaning from a replacement possum milk formula they need a good
mixture of native leaves and flowers, as well as fruits and vegetables. A common mistake is to feed captive possums solely on
fruit and vegetables, which inhibits the correct development of gut microbes required for digestion, and can cause death.
New Zealand
European settlers aiming to establish a fur industry introduced the Common
Brushtail to New Zealand, where there are now about 60 million Common Brushtail Possums.
Their introduction has been ecologically damaging because the native vegetation has evolved in the absence of mammalian
herbivores. The possums do particular damage to broadleaved trees, notably Metrosideros species including rata, leading to
canopy collapse and potentially competing for food with native forest birds. They do not have so much impact on Southern Beech
(Nothofagus), but their presence tends to reduce the species diversity of Nothofagus forest
since they eat many of the other species that would naturally be present. They are said to prey on bird eggs and chicks by New
Zealand farm forestry interests[citation needed]. Possums are also said to be vectors of bovine
tuberculosis, which provides a major threat for cattle and farmed deer although the transmission path has not been
discovered nor proven to exist[citation needed]. Attempts to reduce numbers by trapping and poisoning have had only
short-term success, and the poisons used, usually sodium monofluoroacetate (1080)
or cyanide are environmental hazards in themselves[citation needed].
To prevent damage to young trees it seems to be necessary to keep numbers very low, perhaps 5% of the levels that would be
reached without interference. The possum is widely regarded in New Zealand as a major ecological threat, and some forestry
industry funded ecological organisations such as the Ecologic Foundation encourage
its elimination; however its impacts are compounded by those of other introduced species such as Red
Deer and goats, not to mention human activities such as agriculture, forestry, and mining.
The New Zealand Department of Conservation is the largest
single agency involved in possum control and much possum control is also carried by councils and regional authorities to combat
the threat of bovine tuberculosis.
A small fur industry was developed, and possum trapping and shooting continues to the present day, and the fur is often sold
as 'eco-fur'. The numbers of animals take for fur is significant in relation to the numbers killed in poisoning.
Environmentalists question whether the industry is compatible with the aim of drastically reducing or eliminating possums.
Auckland company Arex International is exporting possum carcasses to Taiwan, Hong Kong and Malaysia for human consumption, where
possum is known as the delicacy kiwi bear.
United States
The Common Brushtail Possum has also been introduced to North America and possibly the Eurasian continent. Environmental
effects have so far been relatively minor perhaps due to the presence of predators that prevent population densities from
becoming excessive.
Gallery
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Common Brushtail Possum eating leaves of a fruit tree
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Common Brushtail Possum - Grampians National Park, Victoria, Australia
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References
- Australasian Marsupial & Monotreme Specialist Group (1996). Trichosurus vulpecula.
2006 IUCN Red List of Threatened Species. IUCN 2006. Retrieved on 12 May 2006.
- Cowan, P. E., et al. (1997). Effects of possum browsing on northern rata, Orongorongo valley, Wellington, New Zealand.
Journal of the Royal Society of New Zealand, 27, 173-179.
- Marsh, K. J., Wallis, I. R., & Foley, W. J. (2003). The effect of inactivating tannins on the intake of Eucalyptus
foliage by a specialist Eucalyptus folivore (Pseudocheirus peregrinus) and a generalist herbivore (Trichosurus
vulpecula). Australian Journal of Zoology, 51, 41-42.
- Payton, I. J., et al. (1997). Response of selected tree species to culling of introduced Australian brushtail possums
Trichosurus vulpecula at Waipoua Forest, Northland, New Zealand. Biological Conservation, 81, 247-255.
- Rogers, G. M., & Leathwick, J. R. (1997). Factors predisposing forests to canopy collapse in the southern Ruahine Range,
New Zealand. Biological Conservation, 80, 325-338
- Groves, Colin (16 November 2005). in Wilson, D. E., and Reeder, D. M. (eds): Mammal Species of the World, 3rd edition, Johns
Hopkins University Press, 50. ISBN 0-801-88221-4.
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