Dusky Hopping-mouse populations contract due to dry conditions
The distribution of the threatened Dusky Hopping-mouse in northern South Australia appears to have contracted following an earlier population expansion in previous years.
Posted 20 June 2018.
Dusky Hopping-mice (Notomys fuscus) are found in the north of South Australia and adjoining states, and characteristically have long hind feet, large ears, dark eyes and a tufted tail tip.
A 2011 study found that the Dusky Hopping-mouse had significantly extended its southwesterly range to areas well inside the Dog Fence and in habitats where they had not previously been recorded.
Exceptional rainfall conditions in 2010 and 2011 and lower rabbit numbers since the introduction of rabbit caliciviris were thought to be contributing factors for the spread of the native rodent. Follow up monitoring in 2012 found fewer numbers of hopping-mice, with signs detected at less than half of the sites (43%) compared to 70% of those surveyed in 2011.
Last month a follow up survey was conducted revisiting sites surveyed in 2011 and 2012 and it was found that the expansion of the species was not sustained beyond the high-rainfall years. Hopping-mice signs were found at just 18% of surveyed sites, with the majority of those outside the Dog Fence. SA Arid Lands Region Community Ecologist Cat Lynch said it is thought the dry conditions over recent years has seen the Dusky-Hopping Mouse distribution reduce to pre-high rainfall areas.
“The results of all of the survey indicates that the Dusky-Hopping Mouse grows in numbers and expands the areas in which it lives in good seasons. With a reduction in vegetation cover and food resources resulting from drier conditions, the hopping-mouse populations reduce, along with the areas that it has previously expanded into,” Ms Lynch said.
Fourteen pastoral stations, mainly south of the Dog Fence were visited to look for signs of the species, with a number of techniques used in the survey including spotlighting, trapping and searching for hopping-mice tracks and burrows. Evidence of associated feral predators and herbivores was also recorded. The survey was led by the SA Arid Lands Natural Resources Management Board and funded through the National Landcare Program, and was supported by landholders and volunteers.
Dusky Hopping-mice are nocturnal and live in small groups in sandy habitats, where they construct and live in burrows which have a series of entrances leading to chambers and tunnels up to a metre below the surface. Ms Lynch said like many other native mammals, numbers of this species have declined greatly due to overgrazing by rabbits and in some areas, livestock. Other threats to the species include predation by cats and foxes, and habitat loss and degradation.