The Rakali Project.
Rakali.
Scientific name:
Hydromys chrysogaster meaning Golden bellied water rat
Pronunciation:
hi-dro-mis, (hydor, water and mys, a rat)
kry-soh-gas-ter (chryso, golden and gaster, belly)
Common Name:
Rakali (RAH-KAH-LEE)
Rakali, Riparian and River Health Project is funded by a State Natural Resource Management Community Stewardship Grant
The River Conservation Society is undertaking research into the wild population of the Rakali, or 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 Rakali’s ancestors are believed to have arrived in Australia from Papua New Guinea approximately 5 – 10 million years ago.
The R.C.S. currently uses the name “Rakali” for these native rodents. This common name is now widely used across Australia and was adopted to try to lift the water rats profile by removing the negative connotations associated with the word “rat”. Rakali are known as Moyitj by the local Ballardong Noongar people.
Rakali have adapted to living with humans, unfortunately to its own detriment, due to being hunted to the point of extinction for its fur before becoming a protected species . Their survival, especially in the highly altered riverine environment of the Wheatbelt, is threatened by habitat alteration both past and present, a decline in water quality 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 waterproof fur coat. It can be identified relatively easily by its large body length, long and thick fur covered tail with a white tip at the end and webbed hind feet.
The Rakali’s 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 (midden) to consume it. Rakali are strong swimmers, allowing them to pursue their prey both on the surface and under water.
Its habitat is usually near permanent bodies of fresh or brackish water and it lives in burrows alongside riverbanks. It has been known to nest in hollow logs along riverbanks and on the edges of pools.
The Rakali 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.
Rakali are an important indicator of aquatic ecosystem health. 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, are they under serious threat of extinction in the Avon River system.
Updates.
Updates 2024
Tuesday 6th February: Photo-point photos were taken at the following Rakali Project pools: Parkers Reach, Mile, Blands, Railway, Gwambygine Park, Gwambygine and Oakover.
A drone survey of Oakover Pool was also conducted, revealing a high level of silt deposits and low water levels in what is left of the main pool. The riparian vegetation consists of a narrow band of Casuarina obesa, Melaleuca and several Eucalyptus rudis on both banks, with an understory of mostly invasive grass. A narrow well shaded channel runs into the upstream end of the pool. Oakover Pool does not represent good Rakali habitat and would not support a permanent Rakali population, only functions as a transit pool during times of higher water flow.
Sunday 7th January: R.C.S. volunteers carried out a ground survey to the upstream end of Oakover Pool and a photo-point was established. Water in the pool is quite shallow.
A drone survey of Little Pool was conducted. This is a very degraded pool with a very high level of silt deposits and low water level. A small well shaded billabong was observed downstream of the remnant pool about thirty metres to the right of the main channel. Although this looks like it would be a good fish and turtle refuge, it is not large enough to support Rakali. The Little Pool complex does not represent good Rakali habitat and would only act as a transit pool during times of higher water flow.
A drone survey of Church Pool was conducted, revealing a substantial body of water approx. 500m long and 20-30m wide, of varying depth with a good variety of submerged logs and snags. Both banks have good tree cover providing shade over the water’s edge, however there is little to no riparian understory except on the water’s edge. This pool appears to provide good Rakali habitat and should support an adequate food supply to sustain a small Rakali population.
Updates 2023
Friday 13th January: Retrieved the cameras from Tipperary Pool. Amongst approx. 35,000 photos of moving branches, rippling water, feral rats, foxes and a lot of native water birds, we captured a couple of photos of a large adult Rakali traveling downstream at 8:11pm on 9/12/2022. This was the only evidence of Rakali, suggesting that this pool does not support a permanent Rakali population.
Cameras were retrieved from Railway Pool. Photos from these cameras revealed a healthy population of water birds, however no Rakali were detected.
Sunday 17th December: Four cameras retrieved from Gwambygine Pool. One camera at the upstream end of the pool detected a Rakali foraging and carrying food on multiple occasions over a three-week period. This camera also captured a Brushtail Possum and a Bat. Multiple water birds were captured on the three other cameras.
Tuesday 12th December: Meares Pool was again surveyed by kayak and three wildlife cameras were retrieved. The water level had dropped considerably since our last visit and salinity was high.
No Rakali were detected in this pool and no evidence of their presents was observed. Meares Pool does not appear to provide suitable Rakali habitat, however, it does support a diverse water bird population and provides good turtle habitat.
Just downstream of Meares Pool, on the downstream side of the Mackie Crossing bridge, a large hole has eroded in the riverbed, creating a deep circular pool about 10-15m across and 3m deep with large boulders in the bottom. This pool is fed by a spring under the bridge and remains full all year round and is often inhabited by a large number of South-western snake-necked turtle (Chelodina colliei)
Gwambygine Park Pool was again surveyed by kayak and the two wildlife cameras were retrieved. Although the water level had droped about 300mm, water quality and clarity was still good. An adult Rakali was filmed foraging for food on two consecutive nights on one of the cameras. No other Rakali were detected over an almost seven-week period, suggesting this pool does not support a permanent Rakali population and as it is only about half a kilometre downstream from Gwambygine Pool, it is possible that Rakali from Gwambygine Pool visit this pool occasionally in search of food.
Monday 13th Tuesday 14th Wednesday 15th November: The Department of Water and Environmental Regulation (D.W.E.R.) deployed nets and monitoring equipment at Gwambygine Pool as part of their Healthy Rivers program.
The five wildlife cameras previously deployed on 2nd November were retrieved, but unfortunately, no Rakali were detected on any of the cameras.
Later in the day, as part of our Rakali, Riparian and River Health Project, D.W.E.R. staff gave a river health presentation to R.C.S. members at Gwambygine Pool and discussed how, as a group, we can make a difference at a local level. Later D.W.E.R. removed the nets and monitoring equipment from the river while showing us what had been found and what this meant in relation to the health of this river pool.
Four cameras were redeployed on Gwambygine Pool. Two close to the upstream end of the pool, and two approx. a kilometre downstream, at the other end of the pool. A feeding midden was found in a small cave just above the water level, where the remains of several gilgies could be seen.
Thursday 2nd November: Gwambygine Pool was surveyed by kayak and it was noticed that some sections of the riverbank had changed, logs and snags had shifted and sand deposits moved as a result of flooding. This altered some sites where Rakali had been detected in the past. Five wildlife cameras were deployed around the pool.
Friday 27th October: Gwambygine Park Pool was surveyed by kayak and two wildlife cameras were deployed. This is a narrow deep pool with steep banks, overhanging tree roots, good riparian vegetation and a good diversity of snags. It appears to be good Rakali habitat.
Meares Pool was surveyed by kayak and three wildlife cameras were deployed. This pool is surrounded by farmland with limited riparian vegetation on the right hand bank and good riparian vegetation on the left hand bank. The pool is moderately silted.
June to October: Due to continued strong river flows and unpredictable water levels, no cameras were deployed for several months. However, land based surveys of river pools and riparian vegetation continued. During a land base survey at Wilberforce pool several whole gilgie bodies, shell fragments and claws were found washed up on the riverbank. This would indicate a healthy gilgie population and good food source for Rakali.
Friday 13th June: The River Conservation Society hosted a meeting to establish an alliance between environmental groups researching Rakali along the Avon and Dale Rivers.
Sunday 26th March: Flash flooding occurred in the Avon River. Two cameras were retrieved from Gwambygine Pool on the 27th, the other two were retrieved several days later when the flooding had further receded. Rakali were detected on both cameras.
Friday 24th March: Gwambygine Pool was surveyed by kayak and four wildlife cameras were deployed. It was observed that sheep were accessing the river in an area that is not fenced. It was noted that severe damage had been done to the riparian vegetation and there was a large quantity of sheep manure on the riverbank, which subsequently washed into the river the following day because of heavy rain.
Tuesday 7th February: Blands Pool was surveyed by kayak and four wildlife cameras were deployed. No evidence of Rakali was found by the cameras
Parkers Reach was surveyed by kayak and four wildlife cameras were deployed. No evidence of Rakali found by these cameras
Updates 2022
Friday 13th January: Retrieved the cameras from Tipperary Pool. Amongst approx. 35,000 photos of moving branches, rippling water, feral rats, foxes and a lot of native water birds, we captured a couple of photos of a large adult Rakali traveling downstream at 8:11pm on 9/12/2022. This was the only evidence of Rakali, suggesting that this pool does not support a permanent Rakali population.
Cameras were retrieved from Railway Pool. Photos from these cameras revealed a healthy population of water birds, however no Rakali were detected.
Wednesday 14th December: Railway Pool was surveyed by kayak and on foot. This pool is heavily silted and has limited riparian vegetation with a high percentage of introduced weeds. Inspection of a downstream sand plug revealed a section of a Carters mussel shell, approx. 65mm long. This shell was old, living Carters mussels have not been recorded in this area since the River Training Scheme was completed in 1972. This pool does not appear to provide good Rakali habitat, however, it could serve as a good transit pool for Rakali traveling between other pools. Three wildlife cameras were deployed on Railway Pool.
Friday 9th December: R.C.S. volunteers kayaked upstream to the head of Tipperary Pool, surveying the pool and riparian vegetation along the way. Although a large section of this pool is heavily silted, there is a deeper section at the upstream end, with submerged logs, substantial riparian vegetation and braided channels entering the pool. Although there was no evidence of Rakali footprints or feeding middens, the pool looked promising as Rakali habitat. Six wildlife cameras were deployed on this pool.
Friday 2nd December: R.C.S. volunteers retrieved six cameras from Wilberforce pool, two from the lagoon and four from the main pool. It appears that we have photos of Rakali on at least four of the six cameras, as well as a great variety of water birds.
Some of the highlights of this outing were the large number of South-western snake-necked turtles (Chelodina colliei) that were seen amongst the fallen logs and snags at the upstream end of the main pool. Also an impressive sight was a juvenile Wedge-tail Eagle that swooped in over our kayak to hunt ducks on the pool.
One camera from Gwambygine Pool revealed two and possibly three different adult Rakali using a burrow over a seven-day period. Two other cameras located 600m and 700m downstream also detected the presents of adult Rakali on several separate occasions. However, it is not possible to say whether these are different Rakali or the same Rakali moving throughout the pool, as the times and date are different.
Thursday 24th November: retrieved the wildlife cameras that we had put out on the Gwambygine Pool a month before. Although we have not had time to go through all the several thousand photos and videos that were on the cameras, a quick skim through has revealed some good evidence of Rakali, with several short video clips of Rakali entering and leaving a burrow. Hopefully once all the camera footage has been examined, we will find more evidence of Rakali living and breeding in Gwambygine Pool.
Later in November a large lagoon just upstream of Wilberforce Crossing was surveyed by kayak and by a land-based inspection of parts of the riverbank. This permanent pool is about 200m long and 20-30m wide with large old Swamp Paperbark trees (Melaleuca rhaphiophylla) overhanging the water on the right-hand bank, providing good shelter and habitat. Fresh Rakali footprints and several feeding middens were found, including a large, freshly eaten, freshwater crayfish species. This was later confirmed by the Department of Water and Environmental Regulation (DWER) to be a gilgie displaying a typical Rakali feeding pattern.
In early November we kayaked down stream from Wilberforce Crossing to Wilberforce Pool which has not previously been surveyed for Rakali presence by the R.C.S. This large, deep, permanent pool is approx. 1km long and 40-50 metres wide and has potentially good habitat for Rakali. A set of large gilgie claws were found in a braided section of the river just upstream of the pool. Several footprints that strongly resembled Rakali tracks were observed, but it was not possible to make a positive identification of these tracks.
In late October following the flood, Gwambygine Pool was surveyed by kayak. We were very excited to discover several sets of Rakali tracks and a couple of feeding middens containing gilgie (Cherax quinquecarinatus) claws and shells. This is an encouraging sign as gilgies are an important source of Rakali food and a healthy gilgie population could be crucial to sustaining or possible growing the Rakali population in Gwambygine Pool.
July 2022 R.C.S. members commenced river pool surveys. Our enthusiasm was quickly dampened by rising flood waters and we had to wait for the river flow to drop enough to safely continue these surveys.
Update December 2021
We are thrilled to announce our “Rakali, Riparian & River Health Project” will be funded through a grant from the State Natural Resource Management Program WA. Our three year project will, amongst other things, monitor and report on the endangered Wheatbelt Rakali. The project is expected to commence in early 2022, keep up to date with our progress by reading our project updates under the “Projects” tab on our Homepage and following us on Facebook and Instagram.
Update May 2019
Bland’s Pool is being surveyed with three wildlife cameras deployed. Rakali were recorded at Gwambygine Pool with three photos taken of two separate animals. Footage was captured at dawn and dusk on three consecutive days indicating healthy water rat activity. Gwambygine Pool is full and has started flowing, Dale River catchment rainfall events are contributing to this. The video below shows two Rakali in another Avon River pool. One was very shy and kept away from us, you can see it swim across the pool at the beginning of the video, the other one swims down the right hand bank ending up very close to us, video was taken at approx 4:45pm, so lucky to see them!
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 riverbanks. 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 behaviours.
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!
Update 2017
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 disappeared 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 infra-red 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.
