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Reducing cockatoo damage to crops | LC0009 |
Ian Temby and Di Marshall, Flora and Fauna Branch
September, 2003 |  |
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This Landcare note gives general advice on reducing crop damage caused by Sulphur-crested Cockatoos, Long-billed Corellas and Galahs. It also includes some practical case studies from farmers who are dealing with the problem. The birds are referred to collectively as ‘cockatoos.’
Background
When large areas of Victoria were cleared for farming, the numbers of cockatoos, particularly the Long-billed Corella, were severely reduced due to loss of major natural foods like Native Yam. Exotic grain crops and introduced weeds like Onion Grass then became their food. The birds adjusted well to this change of diet, but competition with rabbits kept their numbers low.
Figure 1: The Long-billed Corella (Photograph: Ian Temby)
The birds are no longer competing with large numbers of rabbits, (mainly due to the introduction of myxomatosis in the 1950s) and food is readily available. As a result, cockatoo numbers have been increasing in recent times. Long-billed Corellas have now recolonised their traditional range whilst Galahs are spreading further and further south.
They flock in large numbers, descending on paddocks including those with emerging crops and causing significant damage.
In 1995 The Environment and Natural Resources Committee conducted an inquiry into the problems caused by cockatoos. The information contained in this Landcare Note is based on the committee’s report.
The problem
When large flocks of cockatoos form they can cause severe damage to crops. However, it’s important not to assume that crops have been damaged just because birds have been sighted in or near crop paddocks. The crops should be checked for signs of visible damage. Cockatoos are attracted to cereal crops (wheat, oats and barley) and oilseed crops ( sunflower and safflower).
Cockatoo behaviour
Understanding cockatoo ecology and behaviour is the first step in reducing damage.
Cockatoo damage is seasonal
They feed on different crops at different times as they germinate and ripen. Most damage is done to germinating cereal crops in the autumn. In cropping areas, plan your cockatoo campaign in the 3-4 months leading up to sowing. Work with your neighbours and the local Landcare group. Over summer, cockatoos suffer food shortages and the survival of young birds is threatened. Farmers can help in further decreasing population numbers over summer by reducing the availability of food. Reduce access to grain put out for sheep by feeding at or after dusk. Minimise grain residue in the stubble.
Cockatoos are sociable
They flock and roost together. Flocks form through a process known as ‘local enhancement.’ Birds in the air see birds feeding below and join them. The pattern continues until a large flock forms at a favourable food source. Monitor crops regularly. Act as soon as the first birds arrive to prevent a large flock forming.
Cockatoos develop habits
They use regular flight paths and return to good feeding areas repeatedly. Deter the birds early before regular feeding patterns develop.
Cockatoos have seasonal feeding patterns
During summer cockatoos feed early in the morning and late in the afternoon. In winter they can feed all day. Concentrate action at the time it is most needed. Feed stock when the birds are not around.
Cockatoos target specific plants and crops
The birds have adapted well to feeding on commercial crops but their preferred food is a weed: onion grass. Some farmers have ploughed up an area of onion grass away from the crop to expose the corms and create a decoy during sowing. Cockatoos are attracted to onion grass corms in freshly ploughed paddocks. Consider scarifying an area away from the crop as a diversion. Cockatoos are attracted to germinating cereal crops and ripening sunflower and safflower. Monitor crops closely. Be prepared for periods of peak cockatoo activity.
Cockatoos are scared of birds of prey
Kites that simulate birds of prey can work on small paddocks.
Action
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- Sow at the recommended rate.
- Thoroughly cover all grain, avoid and clean up spillage.
- Minimise residual grain in the stubble.
- Direct drill to avoid exposing onion grass corms.
- Sow at the same time as your neighbours.
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- Scare early in the season and early in the day.
- Monitor bird activity regularly and scare often.
- Shift the scare gun regularly. The birds will quickly learn where it is.
- Back up with use of a registered firearm.
- Try broadcasting recorded alarm calls
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Kites, scarecrows, hides and vehicles
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- Combine several methods of scaring.
- Scaring must be unpredictable- shift scarers often.
- Kites that simulate birds of prey, such as eagles and peregrine falcons, may work on small paddocks.
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- Decoy feed as far away as possible from crop.
- Use seconds seed, or plough onion grass to expose corms.
- Continue scaring at crop.
- Extra food will not increase population numbers, it only diverts existing birds from the crop. Food is abundant during cropping time in autumn.
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Planning a cockatoo campaign
Co-operating with your neighbours and the local Landcare group spreads the effort and gives better results.
Work together to monitor bird numbers and whereabouts.
Plan the grain feeding of sheep away from paddocks to be cropped. Or feed at, or after, dusk.
Plant as many paddocks as possible at the same time.
Where practical, sow at the same time as your neighbours.
Develop a schedule of scaring activities. Move scare guns from farm to farm. Visit paddocks to shoot frequently and at different times.
Share the work of monitoring crops. Ensure all paddocks are visited each day during the first few weeks of early growth.
Establish decoy-feeding sites across the district, share the costs of providing and transporting decoy feed. Agree not to disturb birds at decoy feed sites.
Figure 2: Cockatoo damage to a maize crop east of Colac. (Photograph: Ian Temby)
Case studies
Decoy Feeding
Oats seconds
In a South Australian trial of decoy feeding, up to 4,000 Long-billed Corellas were fed 20 tonnes of oats over a ten-week period, during the main sowing and germination phase of winter cereal crops. Taking into account the value of the grain, wages and on-costs, there was an estimated 10-15 fold benefit in increased production. This doesn’t include the lower costs to farmers of reduced scaring activities.
Ploughing onion grass
In Victoria, a grain farmer west of Stawell has had some success with giving Long-billed Corellas and Sulphur-crested Cockatoos ‘free feed’ to distract them during sowing.
He ploughed-up four hectares of Onion Grass 800 m away from the paddock he was sowing. The ploughing was effective in distracting the birds away from the crop but didn’t work when he repeated the activity the next year.
Rice hulls
Two farmers from Picola in northeast Victoria reported greatly reduced damage to their germinating crops when rice hulls were dumped near their properties. The rice hulls were not intended as a decoy, they were simply being disposed of. The hulls provided a very effective decoy at no cost.
Bird of prey kites
A farmer at Telangatuk, near Horsham uses kites that simulate birds of prey to reduce Long-billed Corella damage to his grain crops. The kites are constructed from heavy black plastic and dowel. The crossbars are light wood. When made the kite is around two metres across with the approximate shape of a Kite (the bird) except with a tail.
The kite needs to be launched each morning and is then fixed to a fence into the prevailing wind on 3-400 metres of baling twine. The kites work best on light breezy days. They won’t fly when it’s still, or too windy. The farmer reports that the kites have halved his use of the scare gun. He also shoots with a rifle at peak periods. Whilst this method is used to protect grain crops it is only effective on paddocks of 40 hectares or less.
Figure 3: Bird of prey kite used near Telangatuk. (Photograph:Zoe Elliott)
Patrolling and shooting
A farmer from the Joel Joel area in the northwest of the State protected his wheat and oat crops from corellas with a daily program of patrolling and shooting. With 500 acres of crops sown adjacent to a corella roost site on the Wimmera River the farm is in a high-risk area for corella damage. As soon as the crops were sown the farmer started patrolling the crops on a motor bike with a single shot .22 rifle. He patrolled all day, every day for a ten-week period until the crops were out of danger from the birds.
Legal Controls
Sulphur-crested Cockatoos, Galahs and Long-billed Corellas are classified as “Unprotected Wildlife” under the Wildlife Act 1975.
Shooting and trapping and gassing are allowed under an Order in Council of the Wildlife Act 1975.
The Order states:
“(1) The species of wildlife listed in paragraph (a) above, (Sulphur-crested Cockatoos, Galahs and Long-billed Corellas) may be taken or destroyed by-
(a) landowners or occupiers, their employees and members of their families; or
(b) in the case of recreational reserves, members of committees of management-
only where serious damage is being done to trees, vineyards, orchards, recreational reserves or commercial crops…
“(2) Persons specified in paragraph (1) may take or destroy these species by-
(a) the use of firearms in accordance with the Firearms Act 1958; or
(b) using trapping and gassing equipment approved by the Department of Natural Resources and Environment—only on the freehold or leasehold property on which the damage is occurring.”
Poisons
There are currently no chemicals registered for poisoning cockatoos and poisoning of Long-billed Corellas, Sulphur-crested Cockatoos and Galahs (and all other native birds) is strictly illegal.
Contamination of crops by poisons threatens export markets for all farmers.
Figure 4: Sulphur-crested Cockatoos digging for Onion Grass corms. (Photograph: Ian Temby)
Health and safety
Firearms must be registered and used in accordance with the Firearms Act 1996. The Act prohibits the use of firearms in a town or populous place or on a street, road, thoroughfare or place open to or used by the public. Shooters must be licensed. Cockatoos can carry the disease psittacosis, also known as chlamydiosis or ornithosis. Handling of live or dead birds should be minimised. Care should be taken not to breathe in feather dust. Skin and clothing must be washed after handling cockatoos, or other wild birds.
Further information
Contact the DSE Customer Service Centre on 136 186 for further information.
Services and equipment
Gas guns
E.E. Muir, 542 Foostcray Road FOOTSCRAY 3011 Phone: (03) 9687 6836;
Rural hardware or farm machinery outlets
Bird Frite cartridges
Ask your local ammunition dealer. Cost: $75.00 (approx)/ box of 25.
Trapping and gassing
Trapping and gassing teams may be provided by DSE on request to destroy cockatoos on your property. Contact the DSE Customer Service Centre on 136 186 for further information.
Further reading
ENRC (1995) Report on Problems in Victoria Caused by Long-billed Corellas, Sulphur-crested Cockatoos and Galahs. Parliament of Victoria, Environment and Natural Resources Committee.
The advice provided in this publication is intended as a source of information only. Always read the label before using any of the products mentioned. The State of Victoria and its employees do not guarantee that the publication is without flaw of any kind or is wholly appropriate for your particular purposes and therefore disclaims all liability for any error, loss or other consequence which may arise from you relying on any information in this publication.
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