Update May 2018
The last few months have been very busy with our water rat surveys on the Avon River and the results have been very encouraging. Thankfully the weather has been very kind to us with participants surveying for water rat sign both on the water and along the river banks. Very welcome relief on hot days paddling around the pools.
Hydromys has been very busy this year and it is looking as if we have an active population of water rats (and quite possibly a breeding population) living in the Avon River system and its pools within the York Shire.
The more we learn about the movements and habits of this very shy rodent the more amazed we are due to their habits and behaviors.
These rodents can cover a fair bit of ground during the night on their food foraging trips and are amazingly fast swimmers. They can also become extremely aggressive to intruding feral rodents who happen to encroach on their territory or feeding middens to scrounge a few scraps!
The River Conservation Society is undertaking research into the wild population of the Water Rat (Hydromys chrysogaster) along the Avon River environs. This animal is well adapted to an aquatic life and is one of Australia’s largest rodents.
It was thought that the native water rat had disapeared from the Avon River due to poor water quality. dwindling food sources and the filling in of permanent pools along the Avon River due to sedimentation.
Pictures taken recently by the survey team have been confirmed by the Zoological Department of the University of Western Australia as that of the native water rat (Hydromys chrysogaster) and identified as that of a mature, healthy adult, possibly female. This native rodent appears to be actively foraging at night. Images were obtained using infrared technology located near feeding middens identified during the Society’s surveys of native water rat habitat.
This evidence provides new and interesting information concerning this native rodent’s distribution within Western Australia and is extremely important for the eastern wheat belt region of Western Australia as it was thought to have disappeared from this region in the last 10-15 years. With further research required it may well provide new insight into the genetic diversity of this species in inland regions.
The purpose of the project being undertaken by the River Conservation Society is to establish if there is a breeding population of Hydromys chrysogaster still active within the Avon River region. Should the water rat be deemed under threat then methods will be explored to increase numbers and provide habitat to help protect these native animals.
This is exciting news for River Conservation Society members, the York community and the University of Western Australia. It highlights the importance of the Avon River and the role it plays in protecting the diversity of native fauna and flora along the river and its surrounding riparian zones.
|Figure 1 – Healthy, mature Water rat (Hydromys chrysogaster).||Figure 2 – Typical feeding midden used by Water Rat|
(End of update.)
The River Conservation Society is undertaking research into the wild population of the Water Rat (Hydromys chrysogaster) in the Avon River environs. This animal is well adapted to an aquatic life and is one of Australia’s largest rodents. The water rats ancestors are believed to have arrived in Australia from Papua New Guinea approximately 5 – 10 million years ago.
It has adapted to living with humans, unfortunately to its own detriment, due to being hunted for its fur before becoming a protected species. However the species has become susceptible to potential threats such as habitat alteration due to flood mitigation and urbanisation and predation by introduced animals.
It is a distinctive rodent well adapted to an aquatic existence. A large animal between 23 – 40 cm in length (not including tail) with large webbed hind feet and a water proof fur coat. It can be identified relatively easily by its large body length, long and thick tail with a white tip at the end and webbed hind feet.
The water rats diet consists of large insects, fish and crustaceans and can even include frogs, small lizards and small mammals. Once it catches its prey it usually carries it back to a regular feeding site to consume it.
Its habitat is usually near permanent bodies of fresh or brackish water and lives in burrows alongside river banks. It has been known to nest in hollow logs along river banks or near water bodies and is a strong swimmer.
The water rat is most active around sunset and sunrise but can be seen foraging during the day. Males tend to be solitary animals and are very territorial. They will defend their patch vigorously against other males which intrude into their area.
The purpose of the project being undertaken by the River Conservation Society is to establish if there is a breeding population of Hydromys chrysogaster still active in the region. Are the animals present a unique sub species of Hydromys specially adapted to this inland area and are they under threat, or at worst, have they become extinct from the Avon River system. Should the water rat be deemed under threat in this area then a breeding program will be explored to increase numbers and reintroduce this unique animal back into the Avon River environment.