A skiers guide to the small mammals of the alpine and subalpine region. 

By Garry Mayo. School of Botany and Zoology, Australian National University. 

Illustrations from original pencil drawings (not to scale) by Melinda Perrin (with permission from NSW National Parks and Wildlife Service)

Just occasionally while x-country skiing you might see a small brownish animal on the snow. These animals are the small mammals that live through out the year in our alpine and sub alpine zones. They have adapted to life in the snow and many make use of the space between the ground and the snow called the subnivian space. This space is relatively warm and the temperature is mostly around zero, where there is a reasonable snow cover. Bad snow years are not only a problem for skiers but it can be disastrous for many of the small mammals. Deprived of this insulating layer of snow the animals can succumb to the sub zero temperatures that accompany winter. Ground temperatures approaching minus 30 degrees are not uncommon in the frost hollows of the mountains. 

Locally, the more common small mammal species are the, Mountain Pygmy-possum, Broad-toothed Rat, Bush Rat, Dusky Antechinus and Agile Antechinus. There are some other small mammals, you are very unlikely to see, and these include Smoky Mouse and Eastern Pygmy-possum both of which occur at lower elevations. It is possible that other species may be resident with in the park, such as the Common Dunnart, but as yet have not been found. I have not included the Water Rat, which is significantly larger, but does occur in the park as do a number of bats species. All of these animals are mostly nocturnal however some do forage in the daytime and the most commonly sighted animals during winter are Bush Rats, Broad-toothed Rats and the Dusky Antechinus. There are also non-native animals such as the House Mouse and the Black Rat in the park. 

Identification of the small mammals is generally difficult for those without experience. However some animals do leave tell tail signs and there are several excellent publications with good pictures which will aid identification (see attached list). There are a few things you can do to help identify the animals, but note you must not attempt to capture them. This will stress the animal, you may also destroy its home and it is also illegal. Some of the animals can also inflict painful bites. Glimpses of mammals above the snow are mostly fleeting, if you do see one then stay still and quiet. These animals have relatively poor eyesight, which is more adapted to their nocturnal life, but they can easily pick up movement. They do have excellent hearing and sense of smell. 

  • If you get the opportunity then try to get an idea of its size but note that immature animals will obviously be smaller. 

  • Estimate the relative length of the tail to body. 

  • Is the tail prehensile, i.e. is it able to curl and grasp? This is a characteristic of both species of possum. 

  • Look at the fur (grey, brown or greenish tinge) and tail colour and also note the belly colour if you can see it. 

  • Shape of the head, is it pointed? 

  • Has it left any droppings? Note that the red to orange patches on the snow is the concentrated urine produced by rabbits and hares. 

Bush Rat Rattus fuscipes  

Is a common species and can weigh up to 150 grams. Tail is 90% of the body length. Fur is a grizzled grey to brown. Likes scrubby areas with a lot of ground cover. Ranges more widely in winter into the alpine herbfields when snow covers the ground. Mainly nocturnal. Lives in extensive subnivian tunnel systems. Also lives in burrows in the soil and their winter workings can be seen after the thaw as a trails of soil mixed with the grass. Active throughout the year. These are often mistaken as the introduced black rat in mountain huts. 

 

Broad-toothed Rat Mastacomys fuscus Listed as vulnerable.

 Weighs up to 150g. Tail is around 72% of the body length. Similar in colour to the bush rat but often has a green tinge (particularly in summer) when there is algae growing on the fur as a result of the damp conditions they live in. It can be distinguished from the bush rat by its rounded and compact shape and relatively short tail. Found in larger numbers in wet heaths along watercourses. Produces masses of fecal pellets which are bright green drying to straw colour. Other animals produce droppings that are mostly a dark black colour. They build grass nests and extensive networks of tunnels under the snow that are revealed in the thaw. Active through out the year. 

 

 

Mountain Pygmy-possum Burramys parvus Listed as endangered.

 Was only known from a fossil until the 1960s, however, it was a frequent visitor to some of the chalets in the Victorian Alps which lead to the capture of the first live specimen. Weighs up to 80 grams. Tail is 120% of the body length. Can be distinguished from the Eastern Pygmy-possum by the thickened and fur covered base of its tail. This thickened section is about a centimetre long. The two species of pygmy-possums do not overlap in their distribution. Pale grey in colour lighter underneath with some fawn colouration. 

Mountain Pygmy-possums are generally restricted to boulder fields and need this cool environment in the summer. They have difficulty coping with temperatures over 28 degrees Celsius. Males and females mostly live apart with the females occupying the most productive habitat. The boulder fields are often associated with the mountain plum pine and the while the possums rely extensively on insects for their food that also eat a number of seeds including seeds from this plant. Interestingly the possum has a specialised tooth that is adapted to cracking the hard cases of beetles and seeds. In cracking open the seeds of the plum pine it is the only small mammal that can crack the seeds laterally, rather than along, the length of the seed. In winter they frequently go into torpor (hibernation) for up to 6 days at a time when they can lower their body temperature to just above the freezing point. This saves them a lot of energy. The process of waking from torpor is extremely costly for them energetically yet they need to do this to feed and excrete. They rely on food caches and fat deposits, built up in summer, to see them through the winter.  Some do move around under the snow but it's thought that their movements are limited. Their numbers are declining and although not confirmed it is thought the warmer summers, longer periods with out the snow cover and possibly the noise from machinery (waking the animals from torpor) all affect their survival.

Eastern Pygmy-possum Cercartetus nanus  

Up to 40 grams, fawn in colour and pale to white underneath. Large dark eyes. Eastern Pygmy-possum tail is just shorter than the body Has a thicker and more gradually tapering tail. Not usually found above snow. Is restricted to forests and woodlands and feeds on nectar and pollen as well as insects. Spends most of the winter in torpor. Like the Mountain Pygmy-possum the animal curls into a ball while in torpor to conserve heat. 

Dusky Antechinus Antechinus swainsonii  

Weighs up to 45 grams. The tail is around 80% of the body length. Brown grey in colour and lighter underneath. It is darker and larger than Agile Antechinus, has a pointed face and long curved claws. Typical of both Antechinus species, who are insectivorous (eat insects) and have a very pointed nose and jaw. Found anywhere there is sufficient ground cover but prefers moister sites. As with other Antechinus the males all die after the mating season. That means any animals you see in late September, and for the next few months, will all be females. They mainly eat insects and they live in burrows and hollow logs. Is active throughout winter. 

 

 

 

Agile Antechinus Antechinus agilis (formerly A. stuartii)  

At around 25 grams is much smaller and paler than the Dusky. The tail is around 80% of the body length. It is less common at the higher altitudes around 2000m, prefers woodlands and rocky areas. Its numbers increase with the tree cover. Similar diet to the Dusky but exploits trees more extensively to hunt for beetles. 

 

Smoky Mouse Pseudomys fumeus Listed as endangered. 

Only a few specimens of this animal have been recorded within the park. Weigh up to 70 grams. Tail is 155% of the body length and is distinctly bicoloured, pale to dark grey above and lighter underneath and lightly furred. Feet pink with white fur. Their distribution is restricted to heath where there is a diversity of legumes, epacrids seeds, insects and fungi. Lives in burrows and is tolerant of the cold and active throughout the winter. May not live above the usual snow line and not usually found above snow. 

House Mouse Mus musculus Up to 20 grams. House Mouse tail is a bit shorter than the body. Colours are variable across Australia but generally grey in the park. Identify can be confirmed by a notch behind the tip of the upper incisors. They used to inhabit a number of huts above the snow line although numbers are small and more likely occur in ski resorts. 

 

 

 

Black Rat Rattus rattus Is known from some Victorian resorts and has been recorded in the bush at Kosciuszko may now have established in some resort areas of the park. Weighs up to 280 grams. Has not been able to displace native rats but does get a foothold in areas disturbed by man. You would be unlikely to see one of these at any time outside of the resorts. 

 

 

 

Conservation measures.  

By applying the general rules of conservation you have a good chance of having a minimal effect on any of the native species. 
A few points for special consideration are: 

  • Trampling, particularly in areas where the snow cover is thin, can break through damaging the tunnel networks and allowing cold air to enter their subnivian world. 
  • Attempting to catch the animals is very stressful and can cause their death. 
  • Skiing on and close to drainage lines increases the risk that you will cross areas used by a number of the small mammals and possibility damaging their habitat. 
  • You should not leave food or food scraps anywhere and keeping huts clean reduces the possibility of introduced species getting a hold in the area. 
  • The removal of firewood has a direct impact on home sites and food availability.
  • If "rats" become a problem in ski lodges it is probable that they are native rats or possums. Contact the NPWS and they will trap the animals and release them safely back into their habitat. It is preferable to try to "rat-proof" buildings and storerooms if possible, as the trauma of trapping and releasing a native rat or possum in a strange location may be fatal to the animal.

During winter 2002 and 2003 Glenn Sanecki from the Centre for Resource and Environmental Studies at the Australian National University will research the activity and location of small animals. To do this he is fitting radio transmitters to some animals. Monitoring pipes (90mm stormwater pipe) have been installed in groups of three in  various habitats in the Perisher Range area and are designed to identify animals from hair samples collected. 

There is a lot of good reading about mammals which include: 

  • Wildlife of the Australian Snow Country by Green and Osborne ISBN 0 7301 0461 3. 
  • The Mountain Pygmy Possum of the Australian Alps by Mansergh and Broome ISBN 0 86840 085 8. 
  • The Mammals of Australia Ed by Strahan ISBN 1 87633 4010 
  • Tracks, Scats and other Traces. A field guide to the Australian Mammals by Barbara Triggs ISBN 0 19 553643 6. 
  • The Rodents of Australia. Watts and Aslin ISBN  0 207 14235 1.

 

Rare sighting of  a bird at Perisher.

The Nankeen Night Heron pictured, was observed in a tree at Perisher Valley on the 20th January 2002 and according to Dave Woods, ranger with the NPWS, it is a rare sighting at this altitude and in this area. The bird stayed in the same tree for three days and was timid and if approached too closely it would fly away. It is not known if it built the nest observed in the tree. The bird was not to be seen when NPWS checked a month later.

The Nankeen Night Heron will be nominated as the mascot for the Smiggin Holes Olympics in 2010.

The NPWS is always interested to receive reports of any sighting of birds, animals and plants and can help with identification.

For more information go to footprints, feral animals.