Return to 1616
western barred bandicoot is one of the animals that will be returned to Dirk Har
‘Return to 1616’ is a project that aims to
restore the vegetation and habitats of Dirk Hartog Island National Park to how
Dirk Hartog would have seen them in 1616.
The island has experienced significant changes
since Dirk Hartog landed there on 25 October 1616. Sheep and goats changed the
vegetation, their grazing habits and trampling reducing the food and shelter available
for native species. Efficient new predators, feral cats, added to the pressures
on native species, making it impossible for some to survive.
Ten species of small mammals and marsupials
did not survive the changes to the island’s ecology -
the western barred bandicoot, chuditch, mulgara, dibbler, greater
stick-nest rat, desert mouse, Shark
Bay mouse, heath mouse,
woylie and boodie. Find out more about some of these animals here.
But ‘Return to 1616’ brings hope. With the
sheep believed removed and most of the goats now gone, habitats are returning
to how they would have appeared to Dirk Hartog in 1616. A cat eradication
program is also underway to restore the natural balance of predators to how it
was in 1616. When the cats are gone, ten animals that couldn’t survive the
changes brought by introduced species since 1616 will be returned.
Two extra marsupials will join the
reintroduced species. No evidence has yet been found of
the rufous hare-wallaby
and banded hare-wallaby
previously occupying Dirk Hartog Island but, since they have become extinct on
the mainland and now only occur on other nearby islands, Dirk Hartog Island
will increase their chance of survival.
To help maintain successful shoots,
Judas collars have been fitted to female goats
Plants and habitats must be restored before
small mammals can be returned to Dirk
National Park. To do this
introduced herbivores, goats and sheep, must be removed.
Major destocking efforts began on the island
in 2007 when the pastoral leaseholders removed about 4,000 sheep and 750 goats
from the island by barge. This was in preparation for the change in tenure from
pastoral lease to national park. Teams of DEC staff then culled the remaining sheep
and most of the goats between 2008 and 2013.
To maintain successful shoots as numbers decrease,
DEC staff have fitted Judas collars to over 20 goats. Goats wearing these radio
collars can always be tracked during the collars’ four year battery life.
By collaring only females, the goat
eradication team makes the most of the female goats’ social nature. Female
goats spend time with other females and attract males. The males are more
solitary. The Judas collars are used to find the goats during culling
operations. Goats with Judas collars are not shot during these operations as
they must live to gather and betray another mob.
Although it was estimated that less than
100 goats remain on the island after the February 2013 shoot, the goat
eradication team cannot afford to become complacent. Goats have two breeding
seasons each year. In each season a goat can produce two or three young so the
population will quickly explode if there is a lessening of effort before all
goats are eradicated.
While over 10,000 goats and 5,000 sheep
have been removed from Dirk
since 2007, the last of the goats will be the most challenging to remove. In
2013 the eradication team will incorporate new methods into their operations.
These include luring goats to water points in summer and using aerial infrared
cameras to locate goats in winter.
When this project is complete, Dirk Hartog
Island will be the
largest island in the world from which goats have been eradicated.
Cats have a deva
stating impact on native animals.
Removing feral cats
Cats are efficient predators that have
devastating impacts on native animal populations. The ten species of small
mammals planned for reintroduction cannot be brought onto Dirk Hartog
Park while cats remain.
The cat eradication team has already
started work radio collaring cats, tracking their movements and researching the
effectiveness of baiting, the main control technique.
In 2013 the team is setting up temporary
camps and a network of sand pads and camera traps for monitoring cats before
and after baiting. This will be important for making sure all cats have been
eliminated. They will also construct a fence to divide the island into two
sections to make monitoring more efficient and effective.
Located at the northern end of Herald Bay
and extending nearly 13 km to the west coast, the 1.8 metre high
fence will be made of rabbit netting with an overhang at the top and three
electric wires. A gate will allow vehicles to continue travelling north-south
along the existing track.
The first baiting operation will be south
of the cat-proof fence in autumn 2014. It will be followed by monitoring in the
southern section to find and remove any surviving cats. The next baiting and
monitoring operations will be done north of the fence in 2015. Once each section is deemed cat-free,
success will be verified by an independent team with detector dogs. The dogs
will be trained to react only to cats. They will be muzzled and will follow
scents to cats, stopping and pointing if they find one. This will be followed by two years of
ance in both sections of the island for any sign of cat presence. If
there is no evidence of cats following the checks with dogs, and after two
years of surveillance, the island will be declared free of cats and safe for
the return of native mammals.
This map shows the location of the
cat-proof fence dividing the island and the network of monitoring sites and tracks.