FERAL DEER IN AUSTRALIA

Deer are among the world’s most successful invasive species and can have substantial negative impacts on natural and agricultural ecosystems. They are considered one of Australia’s worst emerging pest animal problems. 

Six species have established wild populations in Australia: the fallow, chital, red, rusa, sambar and hog deer. Numbers of all six are increasing, with populations expanding into new areas.

Most wild deer are currently in south-east Australia, which is where accidental and deliberate releases have occurred in the past. A recent study based on bioclimatic analysis, however, has suggested that most of the species already present in Australia are well-suited to the tropical and subtropical climates of northern Australia. Thus, they could potentially occupy most of the continent, including parts of the arid interior.

In Australia, deer are classified differently, depending on which state they are found. In Queensland, the Northern Territory, South Australia and Western Australia they are classified as a pest species.

But the south-eastern states have not. NSW has listed the damage caused by deer as a key threatening process. Yet under current laws in this state, deer are also protected as a hunting resource. NSW is not alone. Tasmania lists them as partly protected wildlife, and in Victoria they are essentially treated as a protected game species for recreational hunters despite also being listed as a key threat under Victorian threatened species legislation. 

In March 2016, an independent review by the Natural Resources Commission recommended NSW make deer a pest species. Such a move was not supported by the NSW Government, who are obviously too worried about the political repercussions from denying deer hunters their sport. 

Making feral deer a pest species would give land managers and governments the power to tackle this growing environmental and agricultural threat head on, rather than being constrained by current laws that protect feral deer. We also need to prevent further deer farm escapes and the deliberate ‘seeding’ of new areas by hunters. 

Because, to address this pest we need concerted efforts to prevent new populations; to eradicate small, isolated populations; and to contain other wild populations.

            - Janet Cavanaugh

This article was originally published in the VOICES FOR THE EARTH column in The Daily Examiner on September 4, 2017.  

CANE TOADS IN THE CLARENCE VALLEY

Cane toads  were introduced to the north Queensland sugar cane area in the 1930s in the mistaken belief that they would eradicate the cane beetle.  Since then they have been steadily spreading south and west. To the west they have moved across the Queensland savanna into top end of  the Northern Territory ( including into Kakadu National Park) and  further west  into the Kimberley region in the north of Western Australia. To the south they have moved as far as the northern coastal section of the Clarence Valley in the NSW Northern Rivers. There are large populations in and around Yamba and Brooms Head.

Cane toads (Rhinella marina) are poisonous through their life cycle. As these introduced pests advanced they brought devastation to native wildlife which sought to prey on them in the areas they have colonised.  Goannas, snakes, freshwater crocodiles, quolls and dingoes are some of the native species which have died as a result of the toad's poison.

Efforts to eradicate the cane toad have been under way in the Clarence Valley for a number of years.

A community group, Clarence Valley Conservation in Action (CVCIA) Landcare, has been collecting and disposing of cane toads in the Clarence.  The work of these volunteers has been assisted by the National Parks and Wildlife Service, North Coast Local Land Services and local ecologist Russell Jago.

From July 2015 to May 2016 25,000 cane toads have been removed from the Clarence Valley.  71% of these came from Yamba, 17% from Brooms Head, 7 % from Chatsworth Island and 5% from other areas.  In addition 120,000 cane toad tadpoles have been trapped in the same period.  Trapping of tadpoles is a recent development and one it is hoped will cut toad numbers breeding in farm dams.

For further information on the cane toad in Australia refer to the  Australian Museum

Photo: Clarence Valley Conservation in Action Landcare

SAVING NORTHERN TERRITORY QUOLLS FROM CANE TOADS

The Northern Quoll (Dasyuris hallucatus) , a carnivorous marsupial, is the smallest of the four Australian quoll species.  It is listed as endangered under the federal Environment Protection and Biodiversity (EPBC) Act.  In the Northern Territory it was listed as critically endangered in 2012.

 Photo: Australian Wildlife Conservancy

Northern Quolls, once very common in the northern part of the Northern Territory, became critically endangered as feral cane toads[1] spread across the north. Twelve years ago quolls from the Darwin and Kakadu areas were collected and relocated to two cane-toad free islands with suitable habitat off north-east Arnhem Land.  They have flourished there and now number in the thousands.

Some of these quolls are now to be returned to the mainland where they will be trained to leave cane toads alone. Initially they will be re-housed in the Territory Wildlife Park where they will be fed on cane toad sausages.  This food, which will smell like cane toad, will make the quolls ill.  The scientists conducting this conditioned taste aversion program expect that the quolls will learn to reject the toads as a food source. After the training they will be released in the Mary River district of Kakadu National Park which contains suitable quoll habitat.

The animals which are released will be closely monitored so that the success of the program can be gauged.

An earlier trial of this taste aversion in Kakadu led to the survival of some quolls and the passing on of the cane toad aversion to baby quolls – which gives the scientists hope that quolls can be successfully reintroduced to areas where cane toads are living.

There are also plans to use the cane toad sausages with wild quolls in the Kimberley area in the hope this will lead to their survival in spite of the toad invasion.

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[1] Cane toads (Bufo marinus), natives of Central and South America, were introduced to Queensland in 1935 in the mistaken belief that they would control pest beetle in sugar crops.  Since then they have moved south along the east coast with established populations as far south as the Clarence Valley (Yamba and Brooms Head) in NSW and west across the Queensland savanna into the Northern Territory and across into northern Western Australia. They have had a devastating impact on native wildlife which has eaten them  (e.g. goannas and quolls)