Platypus in Country Areas
Courtesy of: The Australian Platypus Conservancy
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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 Island.
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 numbers include:
* 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 Catchment Return to Platypus Page
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 Rio Tinto 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 activities.
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 issues.
* 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. 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.
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