Water rats like high-iron areas

CHRIS THOMAS, SCIENCENETWORK WA 31 AUG 2011



"Little is known about the Australian water rat..."

Image:0ystercatcher, Flickr CC-licensed

Working in collaboration with the City of Cockburn, UWA animal biology honours graduate Claire Smart designed her thesis to provide vital information on the ecology of the Australian water rat and valuable conservation information about Cockburn wetlands.



“Little is known about the Australian water rat, they are severely under-researched all over Australia with most research occurring in the 1950s—this just comprised of vague habitat descriptions or animal sightings.”



Ms Smart’s thesis was one of the first projects to accurately determine the specific habitat requirements of the species in WA.



She surveyed numerous lakes and wetlands in the greater Perth metropolitan area to determine the urban distribution of the Australian water rat and whether its distribution had been affected.



“A large amount of wetlands on the Swan Coastal Plain have been destroyed and, of those remaining, many are degraded, polluted, contaminated or drying out,” Ms Smart says.



“We wanted to see the effect these changes have had on wildlife in those areas.



“Given the drying trend of many South West lakes and rivers, and the declining number of sightings of water rats by the public and DEC, efforts should be implemented to increase local populations.



“The research could help determine suitable translocation sites to set up new populations, or identify other sites in the South West that may be home to water rat populations, to better identify the true range of the species,” she says.



While none of the wetlands investigated by Ms Smart had high levels of toxicants she found water rats were more likely to be found where lead levels are low and iron levels high.



“This is due to the toxicity of lead and, because iron levels are known to increase the productivity of water systems, they indirectly affect water rats by providing greater food sources and habitat health,” she says.



Research results indicated in urban Perth water rats prefer large lake systems with dense fringing habitats, steep and stable bank slopes to create nests in, offshore islands or reed beds for concealment and greater habitat diversity to complement their varied diet.



“It would also be interesting to expand the work to the eastern states to see if the habitat is different, especially given some papers suggest the eastern and western populations may in fact be different sub-species.



“There are also opportunities to try translocations to possibly create new, successful populations, or trying to rehabilitate currently existing populations,” Ms Smart says.



She hopes to expand on her research, increasing the study site to include more of southern WA where populations are known to persist, and trying different trapping techniques.