Platypus live only in Australia, inhabiting a wide range
of flowing and still freshwater bodies from sea level up to an elevation
of more than 1600 metres near the top of the Great Dividing Range. The
species resides along the eastern and southeastern coast of mainland Australia
from the Glenelg River catchment in western Victoria to about as far north as
Cooktown in Queensland. In broad terms, populations still occur in about 80%
of the river basins in Victoria, all of the east-flowing river systems and
about 80% of the west-flowing systems in New South Wales, and around a third
of reliably flowing river basins in Queensland. Predation by salt water crocodiles
and the severe flooding that often occurs along Australian
tropical rivers in the wet season may both potentially contribute to the
platypus’s northern distributional limit.
Platypus is widely distributed in Tasmania, occupying
lakes, ponds and glacial tarns as well as rivers and streams. The species
also occurs in the rivers of King Island, which has been isolated from
Victoria and Tasmania by the waters of Bass Strait for 10,000 or more years.
Only a few platypus specimens were ever collected in
South Australia. Most originated along the Murray River (to as far
downstream as Lake Alexandrina), although some were obtained along the
Torrens and Onkaparinga Rivers before 1900. It is generally accepted that
platypus no longer occur in the wild on the South Australian mainland,
although vagrants moving downstream along the Murray River may occasionally
enter the state. An introduced population is found near the South Australian
mainland on Kangaroo Island, where animals were released in Flinders Chase
National Park between 1928 and 1946. The absence of platypus populations
to the north and west of South Australia undoubtedly reflects the rarity
of reliable surface water in these areas.
The IUCN lists the conservation status of the platypus
as of “least concern” and the Australian commonwealth and relevant state
governments do not consider the species to be threatened (apart from South
Australia, where it is listed as endangered). Nonetheless, there is ample
evidence that platypus populations have declined precipitously in many parts
of their range.
For example, a reasonable (though conservative) estimate
for the number of platypus occupying the Wimmera River basin in western
Victoria at the time of European settlement would have been in the order
of 1500 animals. Mark-recapture studies carried out by the Australian Platypus
Conservancy confirmed that this had declined to less than 200 animals by the
1990s, with animals mainly found in the Wimmera River upstream of Glenorchy
and the Mackenzie River downstream of Lake Wartook. Habitat degradation, channel
sedimentation, use of drum nets that drowned platypus as by-catch, and regulation
of natural flows by the Wimmera Mallee Stock and Domestic System (which by the
1980s exported about half of the annual flow of the upper catchment to storage
reservoirs) would all have contributed to reduced population size.
Further catastrophic losses occurred in the summer of 2006/2007,
when exceptionally dry weather resulted in at least 95% of the Wimmera River channel
upstream of Glenorchy drying out for an extended period of time. Along the Mackenzie
River, a few animals presumably survived this drought in habitats maintained by a
small environmental flow from Lake Wartook, but population size would have been
strictly limited by the small amount of stream channel (c. 12 kilometres)
Similarly, platypus has not to the best of our knowledge
been seen at any location in the neighbouring Avoca River basin since the mid-2000s.
In the Bass River catchment in West Gippsland (where platypus appear to have
been widespread until at least the 1980s), the most recent reliable sighting
dates from 2003.
Factors contributing to the platypus’s vulnerability to
predicted longer-term patterns of climate change include the animals’ complete
dependence on adequate surface water for survival, their characteristically low
population density and low reproductive rate, and the fact that female platypus are
likely to be out-competed for food by larger (and more aggressive) males and therefore
suffer disproportionately high mortality rates when surface water is severely limited.
Grant, T.R. (1998).
The historical and current distribution of the platypus, Ornithorhynchus anatinus,
in Australia. Pp. 232-254 in Platypus and Echidnas (edited by M.L. Augee). The Royal
Zoological Society of NSW, Sydney.
Captive maintenance and breeding at zoos
Platypus is currently maintained at a number of zoos or aquaria,
but are not (as of 2010) on public display anywhere outside Australia.
Platypus appear to have been first displayed to the Australian
public in 1910 by Harry Burrell at the Sydney Zoological Garden, which was then
located at Moore Park. One animal was successfully maintained in a system of tanks
and tunnels for three months, eating a mixed diet of freshwater shrimps, earthworms,
beetle grubs and pond snails. The animal was eventually released into a pond at
another urban park, when the approaching winter created difficulties in providing
it with an adequate supply of food.
Contemporary protocols governing the husbandry of captive platypus
are fundamentally similar to those adopted by Burrell. Animals occupy facilities
which provide feeding tanks or pools linked to nest boxes by narrower tunnels.
They are fed live invertebrate food, mainly comprising freshwater crayfish or
yabbies (Cherax sp.), fly pupae, mealworms and earthworms. Tubifex worms, fly-maggots
and crickets may also be provided. Uneaten food is removed from tanks each day, and
feeding tanks are emptied and scrubbed regularly. The cost of purchasing substantial
quantities of crayfish, along with the large amount of staff time devoted to keeping
tanks and their surrounds clean, means that platypus are one of the most expensive
native mammals to be kept in Australian zoos.
Platypus was bred in captivity for the first time by David Fleay
at Healesville Sanctuary in Victoria. The mother (named Jill) was originally brought
to the Sanctuary in 1938, after being rescued by two men who found her trudging along
a road. The father (named Jack) was captured by Fleay as a young juvenile in 1939,
after being spotted swimming in a local creek. The pair was recorded mating for
the first time in October 1943 and produced a juvenile female (christened Corrie)
who was successfully raised to adulthood. Platypus did not reproduce in captivity
again until the summer of 1998/1999, when two juvenile males hatched at Healesville
Sanctuary, with one surviving to maturity. Since that time, platypus have also
been bred successfully at Taronga Zoo in Sydney. Second generation breeding (i.e.
by a pair of animals who had themselves been zoo-bred) occurred for the first
time at Healesville Sanctuary in 2008/2009.
1944. We Breed the Platypus. Robertson and Mullens, Melbourne. Krueger, B., Hunter, S.
and Serena, M. (1992). Husbandry, diet and behaviour of Platypus Ornithorhynchus
anatinus at Healesville Sanctuary. International Zoo Yearbook 31: 64-71.