Sir Edward Pellew Islands Feral Cat Project

Feral Cats in the Northern Territory

Feral cats have existed for over 100 years in the Northern Territory with distribution rapidly expanding from their very first introduction. With their voracious appetite and ability to adapt to inhospitable conditions, feral cats are a major concern. Some researchers estimate feral cat numbers exceed 100 000 individuals within the Northern Territory alone. This number of cats amounts to millions of small native animals being preyed upon by feral cats each year.

Predation by feral cats is listed as a Key Threatening Process under the Commonwealth Environment Protection and Biodiversity Conservation (EPBC) Act. In particular, feral cats have had substantial impacts on islands where it has been shown they have caused the decline and even the extinction of a large number of native Australian animals.

It has been recognised that the Top End of the Northern Territory is one of the three most important places within Australia where a variety of existing native species are most at risk from feral cat predation. One area particularly under threat is the Sir Edward Pellew group of Islands.

Sir Edward Pellew Islands

Located in the south-west corner of the Gulf of Carpentaria off the coast of the township of Borroloola, the Sir Edward Pellew Islands consists of five large islands and 25 smaller islets and rocky outcrops. The larger islands include West, South West, Centre, North and Vanderlin Islands and they belong to the Yanyuwa, or Saltwater People.

West Island, Sir Edward Pellow Islands	Centre Island, Sir Edward Pellew Islands

With five Northern Territory listed threatened mammal species recorded from the island group, the Sir Edward Pellew Islands are considered to be a particularly important area for mammal conservation. These islands have been found to contain Brush-tailed Rabbit-rats, Northern Phascogales, Canefield Rats, Carpentarian Antechinus and Northern Quolls along with Pale-field Rats, Delicate Mice and Western Chestnut Mice. Other species living on the islands include Northern Brown Bandicoots and Common Rock Rats. There are also 36 significant turtle (Flatback and Green)  nesting areas and 24 significant seabird colonies that have been identified on the islands. The islands are  recognised as an area of National biodiversity significance in the Northern Territory Parks and Conservation Masterplan.

Carpentarian Antechinus	Northern Quoll	Brush-tailed Rabbit-rat
Northern Brush-tailed Phascogale

Feral Cats on the Islands

Fauna surveys carried out in recent years on each of the five large islands have discovered conclusive evidence of cat populations existing on Vanderlin, South West and West. There has been inconclusive evidence of cats living on Centre Island. Locals say that cats have been living on South West and West Islands for 15 to 20 years while Vanderlin Island has had a feral cat population for even longer.

Cat footprints in the sand, West Island

During these fauna surveys it was noted that there was a substantial drop in the trapping success of small mammals generally in the island group. Only one of the five threatened mammal species, the Carpentarian antechinus, was caught during the surveys. This drop in small mammal numbers can be seen to coincide with the introduction of feral cats to the islands.

Some of the Pellew Islands are also home to cane toads, goats, pigs, dogs, cattle, donkeys and horses. The Mabunji Aboriginal Resource Associations li-Anthawirriyarra Sea Ranger Unit, is currently undertaking consultation and planning with the Traditional Owners of the islands to identify what islands, and which feral animals will be removed.

Northern Brown Bandicoot being measured	Common Rock-rat being measured

The Feral Cat Project

In 2008, funding was secured from WWF-Australia, the Natural Heritage Trust, now known as 'Caring for Our Country', (through the Australian Government) and the NT Government to develop a cat eradication project for two of the Pellew Islands, West and Centre Islands. The project involves WWF-Australia, the NT Government, the li-Anthawirriyarra Sea Ranger Unit via the Working on Country program and Charles Darwin University.

The main aims of the project are to, wherever possible, eradicate cats from the Sir Edward Pellew group of Islands, improve our knowledge of the impacts of feral cats on the islands and increase capacity within the NT Indigenous community and Government for cat control.

In June and August of 2008 two 2-week survey trips were carried out on West and Centre Islands. The purpose of these trips was to establish if there is a feral cat population living on Centre Island and to discover the locations and density of feral cat numbers on West Island. Native mammal surveys were integrated into the program to establish which animal species were living in the area. A variety of cat trapping techniques were also trialled.

li-Anthawirriyarra Sea Ranger Involvement

Yanyuwa traditional owners established li-Anthawirriyarra (people of the sea) Sea Ranger Unit to help manage the local Indigenous owned lands. This includes the Sir Edward Pellew Islands. The Sea Rangers are involved in monitoring and managing heritage sites, monitoring and managing turtle and dugong populations as well as surveying, mapping and eradicating feral animals.

li-Anthawirriyarra Stabi-craft boat

An important aspect of the feral cat trapping project is the involvement of the li-Anthawirriyarra Sea Ranger Unit. The project was designed to increase awareness in the Indigenous community of the devastating affect feral cats can have on islands and to provide skills, knowledge and opportunities for the community to continue managing cats in the future. A ‘Feral Cat Storybook’ is currently being developed to assist with community understanding on the importance of managing feral cats.

During the June survey, Sea Rangers assisted with feral cat trapping and were trained in setting up cat trapping lines. The Rangers were taught why it is important to wear gloves and other personal safety equipment when handling cat trapping equipment. Feral cats are extremely wary of anything new in their territory and cat trapping equipment with human scent on it is likely to deter cats from approaching the area. Sea Rangers were shown techniques in trap placement and how to disguise the traps with soil, leaves and branches. Traps were set and baited each day and checked every morning for any captures.

At the completion of the feral cat funded project the Sea Rangers will be given cat trapping equipment so they can continue to carry out the eradication program when working on the islands.

Northern Territory Government Scientists training Indigenous locals in feral cat trapping at Centre Island (Sir Edward Pellew Islands)

 

Setting up a cage trap	A disguised cage trap

 

This feral cat is the first to be trapped on West Island, Sir Edward Pellew Islands. The li-Anthawirriyarra Sea Rangers have been working hard in recent months trapping for feral cats and their efforts have finally paid off.

Results of the Surveys

To date, the results show West Island has quite a number of feral cats roaming its sandy shores. The majority of these cats are living along the outer edges of the island, near coastal waters and presumably close to a remaining prey item, sea bird populations.
West Island appears to have very few, if any, native mammal populations remaining. No native mammals have been trapped or sighted on the island for around 20 years. This corresponds with local information that cats were first introduced between 15 and 20 years ago. As West Island was known as a home for the Northern Brush-tailed Phascogale, this is a disturbing result.

The good news is that after extensive surveys it appears that Centre Island is cat free. The island still contains populations of Northern Brown Bandicoot, Common Rock-rats, Grassland Melomys and Delicate Mice. No Carpentarian Antechinus were captured during fauna surveys and further specific surveys would need to be carried out to discover whether the species still remains on the island.

Please do not take cats to our islands in the Northern Territory.