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through an annual aerial baiting and targeted trapping program – less than
20 per cent of the cat population remains from before controls started in
2004. Foxes, meanwhile, are almost non-existent at Lorna Glen.
Before European settlement, Lorna Glen could have been the habitat for
up to 37 terrestrial mammal species. Recent fauna surveys have confirmed
that only 15 of these, mainly small rodents and small carnivorous
(dasyurid) marsupials, presently occur.
In 2006, surveys uncovered remains of nine species of native
rodents, six dasyurid species, several species of wallaby and the pelvis
and scats of brushtail possums. Non-skeletal evidence of other animals
was also present, such as the many large, mounded warrens created by
boodies on calcrete ridges throughout the area, and remains of stick-nest
rat nests in breakaways.
These historical fauna records were used to select a fauna community
for reintroduction at Lorna Glen. Having virtually eliminated foxes
and reduced cat density by more than 80 per cent, initial releases were
staged in order of perceived vulnerability to predation by feral cats,
with the most resilient established first, including brushtail possums
(Trichosurus vulpecula) and bilbies (Macrotis lagotis) in 2007. Both are
important ecosystem engineers – by digging and burrowing they disturb
the soil, which helps recycle water and nutrients through the earth. Mala
(Lagorchestes hirstus), a species extinct in the wild on the mainland and
known to be more susceptible to predation, were released in 2008.
Boodies and golden bandicoots have also recently been reintroduced
from Barrow Island as part of a Gorgon Gas project environmental offset
program. These were the first animals to be released into a 1100ha fenced
enclosure designed to prevent any predation by feral cats (and foxes)
while the animals acclimatised to their new environment. In October
2010, boodies were taken from the enclosure and released into some of the
old boodie warrens on Lorna Glen and these animals are currently being
closely monitored. In 2011, wild-caught Shark Bay mice and mala from the
Montebello Islands will be released.
About half the animals released were fitted with mortality-sensing
radio transmitters and were intensively monitored for up to five months.
Following the animals to their daytime refuges provided data on
movements and microhabitat selection by free-ranging animals in an arid
environment. It also enabled scientists to target mortality events as soon as
possible after they occurred, to best determine cause of death.
The brushtail possums were either wild-caught animals from Wheatbelt
reserves or from the Australian Wildlife Conservancy’s Karakamia Wildlife
Sanctuary, near Perth. Despite having come from moister climates, the
possums have established well and are living in the large river red gum
(Eucalyptus camaldulensis) hollows, which line the creeks and extend
across the floodplains at Lorna Glen. Recent trapping surveys recorded
new adults, which probably arrived as small pouch young, as well as
females with new pouch young conceived on site.
The bilbies originated from two of DEC’s captive breeding programs
– Peron Captive Breeding Centre in Shark Bay, and the Return to
Dryandra (Barna Mia) facility in the Dryandra Woodland reserve near
Narrogin. Bilbies were also taken from a large wild population, which
was introduced to Thistle Island, off Port Lincoln, South Australia, in the
1990s. Of the three source sites, the Peron Captive Breeding Centre is the
closest in habitat and climate to Lorna Glen and Thistle Island differs the
most. The Thistle Island animals, however, were from a wild, free-ranging
population, an advantage for survival in the new environment.
Fewer bilbies from the wild Thistle Island population were predated by
feral cats or native predators, which is not surprising given that they were
TOP A boodie of the kind
reintroduced from Barrow Island.
LEFT Feral cat numbers were
thinned by an aerial baiting program.
Breakaway country at Lorna Glen.
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