Platypus live-trapping surveys are physically quite
demanding and require specialised knowledge and equipment to carry out properly.
In consequence, our understanding of the distribution of platypus in most
country areas is very sketchy, derived mainly from anecdotal information
gleaned from reports of platypus sightings.
In New South Wales, platypus are believed to survive
in all of the rivers flowing east from the Great Dividing Range, and at least
in the upper reaches of 13 of the state's 16 west-flowing rivers.
In Queensland, the species has recently been reported
in many of the east-flowing rivers between Cooktown and the New South Wales
border, and the headwaters of three of the five river systems draining into
the Murray-Darling Basin. While the animals are still common in parts of
the Atherton Tablelands, they do not appear to occupy any of the waterways
flowing into the Gulf of Carpentaria.
Platypus are believed to be widespread in Tasmanian
waterways, including some streams passing through cave systems. The animals
are also found on King Island, though they appear to be absent from the
islands of the Furneaux group.
In South Australia, platypus are reported only rarely
from the Riverland area of the Murray River and have not been encountered
in the lower reaches of the Murray since 1960. They are believed to be
extinct in the Mount Lofty Ranges. A population descended from introduced
animals (originating in Victoria and possibly Tasmania) survives on Kangaroo
In Victoria, platypus are thought to occupy at least
26 of the state's 31 river systems. The species still seems to be common
in many places, especially parts of the Goulburn and Ovens River catchments
and waterways in the Otway Ranges and East Gippsland. Along the Murray
River, there are few recent reports of platypus downstream of Echuca. The
species may have disappeared from Tidal River on Wilson's Promontory and
rivers along the Portland Coast.
Because so little is known about the status of platypus,
it is impossible to say in most cases whether local populations are secure
or declining. However, based on the results of the Australian Platypus
Conservancy's studies along the Wimmera River, platypus are probably facing
severe problems in some rural catchments.
Factors which can have a serious impact on platypus
* Reduced or seasonally altered river and stream flows.
* Declining water quality.
* Loss of native vegetation along waterways.
* Increased erosion along banks and channels.
As well, predation by foxes and feral cats, deaths caused
by illegal fishing nets and traps, and injuries due to rubbish may all hurt
platypus numbers, while misuse of chemicals (such as pesticides, herbicides,
surfactants and fertilizers) near waterways can disrupt the aquatic food
chain, greatly reducing the platypus food supply.
Case study - Platypus in the Wimmera
In 1997, the Australian Platypus Conservancy began a
major study in the upper catchment of the Wimmera River in western Victoria.
The research was designed to provide baseline information to a coalition
of eleven local Landcare groups, banded together under the title Project Platypus, which was working
to address environmental problems, including severe erosion and increasing
dryland salinity. In particular, it was considered important to determine
precisely where platypus still occurred in the catchment, and what actions would contribute
most effectively to improving their habitat. Given the dearth of information
on the factors which primarily limit platypus populations in farming areas,
it was expected that the program's outcomes would also be of value in helping
to shape waterway management programs in other catchments supporting agricultural
The ongoing research program includes four main elements:
* Wimmera Platypus Watch. Creating a database of local platypus sightings has been
useful in helping to map the animals' distribution in the catchment. Associated
publicity has also helped to improve community awareness of platypus conservation
* Platypus surveys. Live-trapping surveys are providing reliable information
on the status of platypus populations in different parts of the catchment,
and establishing the basis for longer-term monitoring.
* Landholder interviews. Interviews with landholders on properties along the main river
channel and selected tributary streams in the study area are being undertaken
to help define the animals' former distribution, establish when they disappeared
from specific areas, and canvass local opinion as to the factors which have
been primarily responsible for the species' decline.
* Studies of platypus ecology
and behaviour. By tracking the movements of
radio-tagged platypus and describing their burrows and feeding sites, key
habitat attributes of the channel and bank in relation to the animals are
being identified across different seasons.
In the period September 1997 to November 1999 the Conservancy
conducted ten major fieldwork expeditions to the Wimmera. Over 125 sites
were surveyed along more than 140 kilometres of the main river channel and
all its major tributaries in the upper catchment. Platypus were found to
occur in moderately high numbers in the uppermost part of the catchment
near the Pyrenees Range, with more than 90 individuals found near the townships
of Elmhurst and Warrak. Elsewhere, very few platypus were encountered -
in all, over 80% of the platypus caught were found in only 25% of the area
surveyed - confirming observations by local landowners that the species had
declined over much of its traditional range.
The animals generally appeared to be healthy, although
a high rate of scarring was observed on the bill, head, front feet and tail,
probably due to encounters with barbed wire fencing in the water. Unfortunately,
very few platypus were encountered elsewhere in the catchment. These results
were supported by local anecdotal accounts that platypus have declined in
the region over the past two or three decades in response to accelerating
land and water degradation. The results of the first phase of radio-tracking
studies along the Wimmera showed that in winter the animals significantly
prefer using parts of the waterway shaded by trees and having substantial
amounts of woody debris (logs and branches) in the water.
Because the platypus is such a popular "flagship" for
freshwater conservation, this research project continues to have an important
role in motivating landowners to improve the environmental quality of their
local waterways and since 1999 the Conservancy has developed an on-going
survey program to monitor the core platypus population areas. Community
interest in the outcome of the platypus survey program has been very keen
from the outset, with many landholders joining researchers at dawn to see
animals being released back to the wild. These occasions have provided an
ideal forum for researchers to answer questions about platypus and also provide
feedback on how best to manage riparian habitats with respect to wildlife.
Updates on the APC's work in the Wimmera
and other country areas are given from time to time in the APC newsletter