Control Programme of Little and Long Billed Corellas in Busselton

Background

The Corella species building up in numbers and flocking around the Busselton and Dunsborough Townsites are the Little Corella (Cacatua sanguine gymnopis) and the Eastern Long billed Corella (Cacatua tenuirostris). Little Corellas are native to the Gascoyne, Pilbara and Kimberley regions of Western Australia. Eastern Long-billed Corellas are native to south-central New South Wales, south-western Victoria and south-eastern South Australia.

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Flock of Corellas feeding on grass at Port Geographe.

These flocks are thought to be made up of birds previously held in captivity that have either escaped, or were released, and have subsequently bred in the wild.

These species pose a significant threat to native fauna by out-competing for nesting hollows of other native birds and interbreeding with West Australian sub-species of Corella. The Corellas also impact on public amenity and vegetation. Left uncontrolled, issues of noise nuisance and public health, such as faecal contamination of public eating areas, are likely to increase.

Decision

In September 2010 Council initiated a trial control program. The trial Control program determined an effective control method which involves establishment of a feed site where the Corellas are trapped with a net and then euthanised.  With one trapping, the Corella flock was reduced by a third. After running the trial program Council resolved in October 2011 to;

  • Support continuation of a trapping programme to manage Little and Eastern Long Billed Corella populations and that the appropriate approvals, staff training and assistance be obtained from the Department of Environment and Conservation to implement the control programme. 
  • Provide information on the control program via the City’s website and Council for Community Notices, and , 
  • Maintain involvement in the Exotic Corella Working Group (with other SW Councils) to improve coordination with Department of Environment and Conservation services and cost share Corella control activities with other Shires in the South West Region.

Methods

Advice has been sought from Department of Environment and Conservation on control methods. The most effective method for reducing numbers was found to be feeding and trapping. Corellas are attracted to a trapping site by free feeding with bird seed. When the flock is observed feeding at the site the trapping equipment, which essentially consists of a remotely triggered net, is placed on site. When the birds come to feed they are trapped with the net and euthanised either by gassing with CO2 or by shooting. Both euthanising methods are approved, humane methods for destruction of the birds, by the Ethics committee...

Corella numbers appear to decrease during the nesting season (July to November), as mating pairs disperse to inland areas. However, many birds remain in the town sites over the winter period. These are mostly younger, non-breeding, birds which will become fertile and mate in later seasons.

While the numbers of birds present during the nesting season are reduced, they still move about in flocks at various times of the day. During summer, when the breeding pairs and their young have returned, the flock size increases and the daily patterns tend to be more regular. Corellas can be controlled by the feeding and trapping method as long as they are flocking together to feed and therefore trapping can be undertaken at anytime of the year. 

Conditions

The DEC specifies the methods for control, the number of birds that can be taken, and considers the safety aspects of the proposed areas for control.

The person(s) undertaking the control work must also be approved, under license by DEC. The DEC license conditions include:

  • fixed term for control work to be undertaken
  • the number of birds that can be taken
  • requirement to notify the Police before and after each netting session;
  • requirement to report numbers taken to the Shire and DEC;
  • person(s) engaged to euthanise the birds by shooting must have the appropriate firearms licence .

Frequently asked questions in relation to Corellas and the Shire Control Program can be found in the City of Busselton's Bay to Bay article, and the attached document from the Department of Environment and Conservation.