How many feral cats are too many?
Healthy breeding populations of the threatened bilby exist in the marsupial’s last refuges, mostly on Aboriginal land, a groundbreaking program spearheaded by Indigenous rangers in central Australia has indicated.
A cross-border Bilby Blitz was held earlier this year to provide a snapshot of how the vulnerable mammal is faring in its last remaining habitats.
Bilby tracks, scats and burrows were found in 58 of 249 areas surveyed by rangers from 11 groups in the Northern Territory and Western Australia. A new tri-lingual app in English, Warlpiri and Warumunguwas used in the work.
The Central Land Council said the results of the blitz are good news, with Indigenous rangers reporting they found signs of bilbies where they expected them to be — and they appeared to be in reasonable numbers.
“This suggests there are healthy breeding populations in these last refuges, which are mostly on Aboriginal land,” Central Land Council land management manager Peter Donohoe said.
Mr Donohoe said the 249 areas of two hectares surveyed were in places bilbies were expected to be found, had been recorded in the past or where there was the greatest chance of finding them.
New bilby populations were found at Kiwirrkurra in WA and the northern Tanami in the NT. Mr Donohoe said the only area where rangers didn’t find any signs of bilbies — even though some had been sighted there before — was east of Barrow Creek.
“The rangers found old burrows but no fresh evidence, so more surveys will be needed,” he said.
Signs of the bilby’s main predators — cats and foxes were also recorded. The data raised questions about which feral animals posed a greater threat.
“Rangers found cat signs in 111 of the 249 track plots, including where many signs of bilbies were also found,” Mr Donohoe said.
“This means that bilbies can survive living side-by-side with cats, but we don’t know how many cats is too many.”
Rangers found evidence of foxes in only 50 of the track plots, but there were fewer or no signs of bilbies in the areas where foxes were present.
“We found more evidence of bilbies in the areas where there were cats,” Mr Donohue said.
“Perhaps that means that foxes have a greater impact on bilby numbers than cats and that a single fox is one too many.”
“We need to do more research about the dynamics of feral hunters, their relation with the dingo, and their combined impacts on the bilby.”
Data from the surveys will help the federal government’s upcoming bilby recovery plan.
“It’s the first time a Commonwealth threatened species recovery plan has been developed with the assistance of an Aboriginal subcommittee, and that rangers on that committee have had substantial input,” Mr Donohoe said.
By Wendy Caccetta