Nature & Conservation

Return to 1616

Western barred bandicoot

The western barred bandicoot is one of the animals that will be returned to Dirk Hartog Island

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 underway to restore the natural balance of predators. When the cats are gone, ten native animal species and two extra marsupials will be returned.


Removing goats

Collaring a goat

Plants and habitats must be restored before small mammals can be returned to Dirk Hartog Island 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 Parks and Wildlife staff then culled the remaining sheep and most of the goats between 2008 and 2013.

To maintain successful shoots as numbers decrease, Parks and Wildlife staff fitted Judas collars to some female goats in order to track their whereabouts on the island. Female goats spend time with other females and attract males which are more solitary. The Judas collars are used to find the goats and their mobs during monitoring and culling operations.

While over 10,000 goats and 5,000 sheep have been removed from Dirk Hartog Island since 2007, the last of the goats will be the most challenging to remove. It is estimated that less than 50 goats remain on the island in 2015.

When this project is complete, Dirk Hartog Island will be the largest island in the world from which goats have been eradicated.


  Removing cats

Collared cat

Cats have a devastating impact on native animals.

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 Island National Park while cats remain.

The cat eradication team started work by radio collaring cats, tracking their movements and researching the effectiveness of baiting, the main control technique.

In 2014 the cat team constructed 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 is made of rabbit netting with an overhang at the top and three electric wires. A gate allows vehicles to continue travelling north-south along the existing track. 

The southern area was then intensively monitored after baiting in May 2014 until July 2015. Four types of traps were used: automated camera traps, sand pads, soft leghold traps and cage traps. All traps used scent lures to attract cats as food lures were more likely to attract other animal species.  Final checks south of the fence were done using detector dogs after no feral cat sign had been found for more than six months. While the dogs were doing final checks south of the cat-proof fence, monitoring for cats north of the fence was in full swing and the cat team hope to be ready to have dogs checking the northern part of the island in 2017.

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.

Cat fence and padsThis map shows the location of the cat-proof fence dividing the island and the network of monitoring sites and tracks.


Weed management

Invasive weeds threaten natural ecosystems by displacing native species. When weeds displace native plants, animals are left without their natural homes and food. Consequently managing weeds is an important part of land management and ecological restoration.

High risk species are those that are most likely to adversely affect an area so priority is given to managing high risk species. The Dirk Hartog Island Weed Management Plan recommends management of the following weed species on Dirk Hartog Island:

Scientific Name

Common Name

Ecological Impact

Objective

Cynodon dactylon

Couch

High

Eradicate

Ricinus communis

Castor oil plant

Moderate

Eradicate

Schinus terebinthifolius

Japanese pepper

High

Eradicate

Lupinus cosentinii

Lupin

Moderate

Eradicate

Raphanus raphanistrum

Wild Radish

High

Eradicate

Mesembryanthemum crystallinum

Ice plant

High

Control

Polycarpon tetraphyllum

Fourleaf allseed

Low

Control

Reichardia tingitana

False sowthistle

High

Control

The ‘high risk alert species’ listed below have been recorded in Shark Bay but are not currently known on Dirk Hartog Island. It is important that any sightings of these species on the island are reported so they can be checked and dealt with promptly.

Family

Scientific Name

Common Name

Polygonaceae

Acetosa vesicaria

Ruby dock

Amaranthaceae

Aerva javanica

Kapok bush

Papaveraceae

Argemone ochroleuca

Mexican poppy

Solanaceae

Lycium ferocissimum

African boxthorn

Asteraceae

Verbesina encelioides

Crownbeard

Keeping exotic plants and animals off Dirk Hartog Island is crucial to the success of the Return to 1616 project. All visitors to Dirk Hartog Island are encouraged to follow the example of Parks & Wildlife in making sure their vehicles, trailers, boats and equipment are clean and free from soil, weeds and animals. See Island protection for more about how you can help keep the island free of pests.


Gorgon Barrow Island Net Conservation Benefits Fund

The Dirk Hartog Island Ecological Restoration Project is funded by the Gorgon Barrow Island Net Conservation Benefits Fund with additional funding from the Department of Parks and Wildlife. 

The Fund is administered by the Department of Parks and Wildlife and approved by the Minister for Environment after considering advice from the Gorgon Barrow Island Net Conservation Benefits Advisory Board.


Publications

DHI visitor guide Return to 1616 - Island protection brochure  Wrens of DHI brochure See the Current Update
Dirk Hartog Island
National Park
Visitor Guide
(3.6MB)
Return to 1616
Island protection
(3MB)

Wrens of
Dirk Hartog Island
(1MB)
 

Reports

Biosecurity Implementation Plan, June 2015

A pilot study for the proposed eradication of feral cats on Dirk Hartog Island, Western Australia. Algar et al.

A bait efficacy trial for the management of feral cats on Dirk Hartog Island. Johnston et al.

Field efficacy of the Curiosity feral cat bait on three Australian islands. Johnston et al.

Population Structure and Management of Invasive Cats on an Australian Island. Koch et al.

Interim report A survey for black rats (Rattus rattus) in the Shark Bay communities of Denham, Monkey Mia and Useless Loop. Palmer, R & Morris, K. 


Media Releases

Dirk Hartog Island close to full pest eradication, ahead of 400th anniversary (ABC Rural)

Cats' days are numbered as island returns to the call of the wild (Weekend Australian)

Program to restore historic WA Island (Northern Guardian)

Turning back the clock on feral island (Australian)

Clock turned back 400 years on Dirk Hartog Island (Ministerial media statement)