A group of dedicated volunteers is helping to shed light on Platypus populations in the upper Murrumbidgee River.
In the chill of an August dawn, the upper Murrumbidgee River is mirror-like, reflecting the place where the shadows of Bredbo Gorge give way to the alluvial flats of Scottsdale Reserve. Twelve Bush Heritage volunteers wait in hides along the edge of the river, each silently scanning a 50-metre stretch of water for a glimpse of Platypus.
“It was sensational, absolutely sensational,” says Mario Russo, a regular volunteer and supporter of Scottsdale Reserve.
It was also minus 8 degrees.
“The Bush Heritage volunteers are a pretty tough breed,” laughs Antia Brademann, Cooma Region Waterwatch Coordinator.
This is the 6th year that volunteers have surveyed Platypus at Scottsdale as part of Waterwatch’s ‘Platypuswatch’ program. In the absence of any other long-term monitoring, the data collected by volunteers is essential to understanding the health of Platypus populations in the Upper Murrumbidgee.
“Everyone has this idea that the Platypus are there and they’re very common,” says Antia. “We’re really interested to see if that’s really the case, and without these surveys we wouldn’t be able to do this in our catchment.”
Each year, volunteers survey 12 sites at Scottsdale, twice a day, over three days using the group survey protocols developed by the Australian Platypus Conservancy. August is the time of year when volunteers are most likely to spot Platypus, as this is when they shrug off their natural wariness and prepare to breed.
This August, the survey team recorded only three Platypus at Scottsdale, compared with five or six in previous years. It’s likely this is due to low river flows this year; low flows can affect abundance of aquatic insects and other macroinvertebrates, which females need in large supply in order to build up their fat reserves prior to breeding. Studies of other Platypus populations have found that females are less likely to breed under these conditions. And when Platypus are not inclined to breed, they revert back to their skittish selves, wedging themselves under rocks on the riverbed for up to 10 minutes at a time, if frightened.
“Our sightings were down across the whole region,” says Antia.
Improving the health of the upper Murrumbidgee – and hence the quality of Platypus habitat – is a central focus of Bush Heritage’s conservation work at Scottsdale, and that of our neighbours all along the river. Willow trees that block waterflows have been removed, and river banks have been revegetated to prevent erosion.
Mario did spot a Platypus, but it was in the survey zone next to his. “Officially, no, I saw no Platypus. Unofficially, I saw one.”
The sub-zero mornings have not deterred Mario from participating in future Platypus surveys. He found the quiet time on the river meditative; a chance to become deeply immersed in the sounds of the bush around him.
“It only went for an hour each time, and for me that hour just didn’t happen. I was so transfixed by my surrounds and what I was doing.”