It was a routine, crisp Autumn night out in the field. Daniel Burton, Australian Wildlife Conservancy (AWC) Sanctuary Manager, was conducting feral predator control 10m outside the northern boundary of Scotia Wildlife Sanctuary's (on Barkandji country) 8,000 hectare fenced area when something small and unfamiliar sprinted by his vehicle. Blink once and he might have missed it.
Daniel pulled on the handbrake and hopped out of his 4WD. He carefully approached the nimble individual, making note of its unique appearance. The little critter looked like a mouse, Daniel was certain of that, but not any mouse he'd seen in the two years working and living at the south-west New South Wales sanctuary. Its eyes were wider, ears bigger, its tail longer, black and bushy. It was twice the size of a house mouse, and it wasn't running, it was hopping.
Back at Scotia's homestead, Daniel searched the mammal guide, hoping to identify the individual. He narrowed it down to four potential species - the Dusky Hopping Mouse, Spinifex Hopping Mouse, Fawn Hopping Mouse and Kultarr. He ran the options by Dr Laurence Berry former AWC Senior Ecologist who said, "we don't have any of these species at Scotia", to which Daniel responded, "well, we have one now!".
And the work to identify the species began.
AWC Following guidance from Laurence, Daniel set up camera traps in the discovery area. Just one image of the individual could help the team learn more about the critter and track its nightly whereabouts. Thousands of pictures were captured of multiple different individuals, as were dozens of pictures of feral cats.
"On the same cameras outside the fence that picked up the mouse, we also picked up several cats," Daniel explained. "I was worried about how this might impact the little guys, so we conducted feral predator control in the area and removed 15 of the predators."
With more cameras set up in targeted locations, and everyone keeping an eye out, a growing number of detections were being made both inside and outside the fenced area. However, it was three months before the team was able to capture one of the small individuals, after undertaking a couple of opportunistic trapping sessions.
AWC "We opportunistically set up Elliott Traps on a few occasions, and three months later we safely captured one mouse outside the fence,"
Trevor Bauer, AWC Field Ecologist, said. "We caught one individual in July 2022, a male that we nicknamed Patches. We took measurements of his head, tail, body, ears, his feet and pads. He had a throat pouch with fur pointing towards the centre. We had a good idea of the species but took fur clippings and tissue samples for genetic testing to be certain."
The sample was sent off to the Australian Museum in September 2022. By May 2023, eight months later and 12 months after the first sighting, the results came back. Thanks to the little guy, Daniel and the team were finally able to put the case of the mysterious mouse to bed.
Recorded for the first time at Scotia Wildlife Sanctuary and 100 km from its closest confirmed location was the vulnerable Dusky Hopping Mouse (Notomys fuscus).
Daniel Burton/AWC "We're really excited, to say the least," Daniel said. "It's a new species for Scotia and a significant extension for the Dusky Hopping Mouse's range which was last recorded around Broken Hill, over 100km away."
As a boom-and-bust species, the Dusky Hopping Mouse will increase in population when environmental conditions are good and food resources are plentiful and fall in number during times of drought and scarcity.
Dr Rachel Ladd, AWC Wildlife Ecologist, said the species' presence can be attributed to fantastic conditions following consistent rainfall over the last three years.
"We were surprised to find the species happily living and thriving in the area, and believe it is an indication of the good conditions we've recently experienced," Dr Ladd said.
Daniel Burton/AWC While the risk of drought may reduce the Dusky Hopping Mouse's numbers in future years, Dr Ladd said long-term data from Scotia and other sanctuaries with feral predator free fenced areas indicate that native species have higher densities where there's the reduced risk of predation by feral predators.
"The Dusky Hopping Mouse's range has contracted significantly since European colonisation and the introduction of predators such as cats and foxes," Dr Ladd explained. "We are hoping that the reduced threat of predators inside the fenced area will be key to the species persisting at Scotia during drier years."
