The
common brushtail possum (
Trichosurus vulpecula, from the
Greek for "furry tailed" and the
Latin for "little fox", previously in the genus
Phalangista[4]) is a
nocturnal, semi-
arboreal marsupial of the family
Phalangeridae, native to
Australia, and the second-largest of the
possums.
Like most possums, the common brushtail possum is
nocturnal. It is mainly a
folivore, but has been known to eat small mammals such as rats. In most Australian habitats, leaves of
eucalyptus are a significant part of the diet, but rarely the sole item eaten. The tail is
prehensile and naked on its lower underside. The four colour variations are silver-grey, brown, black, and gold.
[5]
It is the
Australian marsupial
most often seen by city dwellers, as it is one of few that thrive in
cities and a wide range of natural and human-modified environments.
Around human habitations, common brushtails are inventive and determined
foragers with a liking for fruit trees, vegetable gardens, and kitchen
raids.
The common brushtail possum was introduced to New Zealand in the
1850s to establish a fur industry, but in the mild subtropical climate
of New Zealand, and with few to no natural predators, it thrived to the
extent that it became a
major agricultural and conservation pest.
Description
Skeleton of common brushtail possum
Skull of a common brushtail possum
The common brushtail possum has large and pointed ears. Its bushy tail (hence its name) is adapted to grasping branches,
prehensile at the end with a hairless ventral patch.
[6][7] Its fore feet have sharp claws and the first toe of each hind foot is clawless, but has a strong grasp.
[7] The possum grooms itself with the third and fourth toes which are fused together.
[7]
It has a thick and woolly pelage that varies in colour depending on the
subspecies. Colour patterns tend to be silver-grey, brown, black, red,
or cream. The ventral areas are typically lighter and the tail is
usually brown or black.
[6][7] The muzzle is marked with dark patches.
The common brushtail possum has a head and body length of 32–58 cm
[6] with a tail length of 24–40 cm.
[7] It weighs 1.2-4.5 kg.
[7]
Males are generally larger than females. In addition, the coat of the
male tends to be reddish at the shoulders. As with most marsupials, the
female brushtail possum has a forward-opening, well-developed pouch.
[6]
The chest of both sexes has a scent gland that emits a reddish
secretion which stains that fur around it. It marks its territory with
these secretions.
[8]
Biology and ecology
Range and habitat
The common brushtail possum is perhaps the most widespread marsupial
of Australia. It is found throughout the eastern and northern parts of
the continent, as well as some western regions,
[9] Tasmania
[10] and a number of offshore islands, such as
Kangaroo Island[11] and
Barrow Island.
[12][13]
It is also widespread in New Zealand since its introduction in 1850.
The common brushtail possum can be found in a variety of habitats, such
as forests, semi-arid areas and even cultivated or urban areas.
[6][7] It is mostly a forest inhabiting species, however it is also found in treeless areas.
[7] In New Zealand, possums favour broadleaf-podocarp near farmland pastures.
[14] In
southern beech forests and pine plantations, possums are less common.
[14] Overall, brushtail possums are more densely populated in New Zealand than in their native Australia.
[15] This may be because Australia has more fragmented
eucalypt forests and more predators. In Australia, brushtail possums are threatened by humans,
tiger quolls,
dogs,
foxes,
cats,
goannas,
carpet snakes, and
powerful owls. In New Zealand, brushtail possums are threatened only by humans and cats.
[15] The IUCN highlight the population trend in Australia as decreasing.
Food and foraging
Dentition of a common brushtail possum
The common brushtail possum can adapt to numerous kinds of vegetation.
[15] It prefers
Eucalyptus leaves, but also eats flowers, shoots, fruits, and seeds.
[15] It may also consume animal matter such as insects, birds' eggs and chicks, and other small vertebrates.
[16]
Brushtail possums may eat three or four different plant species during a
foraging trip, unlike some other arboreal marsupials, such as the
koala and the
greater glider, which focus on single species. The brushtail possum's rounded molars cannot cut
Eucalyptus
leaves as finely as more specialised feeders. They are more adapted to
crushing their food, which enables them to chew fruit or herbs more
effectively. The brushtail possums' caecum lacks internal ridges and
cannot separate coarse and fine particles as efficiently as some other
arboreal marsupials.
[15] The brushtail possum cannot rely on
Eucalyptus alone to provide sufficient protein.
[17] Its more generalised and mixed diet, however, does provide adequate nitrogen.
[18]
Brushtail possums feeding
Behaviour
Brushtail possum (brown form)
The common brushtail possum is largely arboreal and nocturnal. It has
a mostly solitary lifestyle, and individuals keep their distance with
scent markings (urinating) and vocalisations. They usually make their
dens in natural places such as tree hollows and caves, but also use
spaces in the roofs of houses. While they sometimes share dens,
brushtails normally sleep in separate dens. Individuals from New Zealand
use many more den sites than those from Australia.
[19]
Brushtail possums compete with each other and other animals for den
spaces, and this contributes to their mortality. This is likely another
reason why brushtail possum population densities are smaller in
Australia than in New Zealand.
[15] Brushtail possums are usually not aggressive towards each other and usually just stare with erect ears.
[15] They vocalise with clicks, grunts, hisses, alarm chatters, guttural coughs, and screeching.
[6][7]
Reproduction and life history
Brushtail possum with young
The common brushtail possum can breed at any time of the year, but
breeding tends to peak in spring, from September to November, and in
autumn, from March to May, in some areas. Mating is promiscuous and
random; some males can sire several young in a season, while over half
sire none.
[15] In one Queensland population, males apparently need a month of consorting with females before they can mate with them.
[20] Females have a gestation period of 16–18 days, after which they give birth to single young.
[6][7]
A newborn brushtail possum is only 1.5 cm long and weighs only 2 g. As
usual for marsupials, the newborn may climb, unaided, through the
female's fur and into the pouch and attach to a teat. The young develops
and remains inside the mother's pouch for another 4-5 months. When
older, the young is left in the den or rides on its mother's back until
it is 7-9 months old.
[6][7] Females reach sexual maturity when they are a year old, and males do so at the end of their second year.
[6][7]
Female young have a higher survival rate than their male counterparts
due to establishing their home ranges closer to their mothers, while
males travel farther in search of new nesting sites, encountering
established territories from which they may be forcibly ejected. In the
Orongorongo
population, female young have been found to continue to associate with
their mothers after weaning, and some inherit the prime den sites.
[21]
A possible competition exists between mothers and daughters for dens,
and daughters may be excluded from a den occupied by the mother.
[22]
In forests with shortages of den sites, females apparently produce more
sons, which do not compete directly for den sites, while in forests
with plentiful den sites, female young are greater in number.
[22] Brushtail possums can live up to 13 years in the wild.
[6][7]
Brushtail
possum exhibiting exudative dermatitis, a condition that often results
from stress associated with overcrowding, particularly in young males
attempting to assert territory
Relationship with humans
Abandoned baby possum with Fauna Rescue volunteer, Adelaide, South Australia
The common brushtail possum is considered a pest in some areas, as it
is known to cause damage to pine plantations, regenerative forest,
flowers, fruit trees, and buildings. Like other
possums,
it is rather tolerant of humans and can sometimes be hand fed, although
it is not encouraged, as their claws are quite sharp and can cause
infection or disease to humans if scratched. It is a traditional food
source for some indigenous Australians.
Australia
Its
fur has been considered valuable and has been harvested. Although once
hunted extensively for its fur in Australia, the common brushtail possum
is now protected in mainland states, but it has only been partially
protected in Tasmania, where an annual hunting season is used. In
addition, Tasmania gives crop-protection permits to landowners whose
property has been damaged.
[8]
While its populations are declining in some regions due to
habitat loss, urban populations indicate an adaptation to the presence
of humans.
[23]
In the mainland states, possum trapping is legal when attempting to
evict possums from human residences (e.g. roofs), but possums must be
released after dusk within 24 hours of capture, no more than 50 m from
the trapping site. In some states, e.g. Victoria, trapped possums may be
taken to registered veterinarians for euthanasia.
[24] In South Australia, they are fully protected and permits are required for trapping possums in human residences
[25] or for keeping or rescuing sick or injured wild possums and other native animals.
[26]
New Zealand
Since its
introduction
from Australia by European settlers in the 1850s, the common brushtail
possum has become a major threat to New Zealand native forests and
birds. It is also
a host for the highly contagious
bovine tuberculosis.
[8] (This is not an issue in Australia, where the disease has been eradicated).
[27]
By the 1980s, the peak population had reached an estimated 60-70
million, but is now down to an estimated 30 million due to control
measures. The New Zealand Department of Conservation controls possum
numbers in many areas via the aerial dropping of
1080-laced bait.
[28] Hunting is not restricted, but the population seems to be stable despite the annual killing thousands of the animals.
[8]
Binomial name
Trichosurus vulpecula
Common brushtail possum range
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