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Reducing cockatoo damage to fruit, nuts, grapes and flowers | LC0013 |
Ian Temby, Flora and Fauna Branch
September, 2003 |  |
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This Landcare Note discusses options available for controlling cockatoo damage
Introduction
Long-billed Corellas, Sulphur-crested Cockatoos and Galahs (referred to collectively as ‘cockatoos’ and illustrated in Figure 1) are well known for damaging germinating cereal crops. They can also cause damage to:
- commercial fruit and nut trees;
- grape vines;
- commercial flower crops.
In some cases, these problems are merely a nuisance; in others, serious damage can be caused. Many of the damage control measures suggested here can be used to deter other bird species.
Figure 1
1. Long-billed Corella Cacatua tenuirostris
2. Sulphur-crested Cockatoo Cacatua galerita
3. Galah Cacatua roseicapilla
Why do cockatoos cause damage?
Cockatoos cause damage by eating and by chewing non-food items. Chewing maintains their beaks at the correct length and condition. Almost all problems caused by cockatoos relate to their eating or chewing behaviour. The severity of many cockatoo problems is due to the social nature of cockatoos - they do most things in flocks.
Cockatoos always flock together to roost.
At night the noisy roosting behaviour of cockatoos can be a problem for nearby residents. Day roosts, used sometimes for several hours between feeding bouts, are often used repeatedly. Day roosts may also be casual or short-term rest stops. Wherever cockatoos land either feeding or beak maintenance chewing usually occurs, and damage may be caused.
Specific problems
Commercial fruit and nut trees
Cockatoos cause damage to fruit and nut trees by pruning growth and feeding on fruits and nuts. It is important not to allow the birds to develop a pattern of feeding at the crop. Bird hides made of hessian or other material can be used for shooting. Vehicles left at the crop site can also serve as hides.
Concealed gas guns should be used in combination with Bird Frite® cartridges and shooting. The gas guns should be moved every two days, turned off at night and have the firing interval changed frequently. It is important to deflect the birds as they approach the crop.
Providing an alternative, low-cost food source such as rice hulls or almond processing residue can assist in deflecting birds. The decoy food source should be at least 500 m away from the crop so the birds are not disturbed by scaring activities at the crop site. Do not disturb the birds at the decoy site. Decoy sites are more effective when they are close to the flight path of the birds and to trees that can be used as perches or roost sites. Decoy model cockatoos in the feeding posture can be used to lure birds to the decoy feed site. Commercial growers should assess and record losses caused by cockatoos so they can determine whether major exclusion projects like netting will be cost-effective.
Grape vines
Cockatoos damage vines through pruning and snipping off grape bunches. Limiting nearby food sources, or moving the birds from local roost sites may help to reduce losses. If the birds are discouraged from roosting nearby their pruning and snipping behaviour (for beak maintenance) may be directed elsewhere. To move birds from a roost site use a combination of Bird Frite® cartridges and taped alarm calls, reinforced by some shooting. Concentrate the action when the birds are returning to the roost.
If birds must be moved from a night roosting site, then a similar strategy should be used, along with scaring at night with spotlights and Bird Frite® cartridges. The birds will generally move to another site within a week of starting the program, but it could take longer. Deterring birds at a new roost site is easier than at a site where they are well established. At the crop site a combination of scaring and shooting, using bird hides, Bird Frite® cartridges, taped alarm calls and gas guns, may be effective.
Visual screens made from shade cloth or other material 2-2.5m high can also deter cockatoos from entering the crop. If only a small number of birds are involved destruction may be useful and cost-effective, provided there are no food or roosting attractions in the area that continue to draw more birds in. Grape growers should record and assess all losses caused by cockatoos and other birds to determine whether major exclusion projects like netting will be cost-effective.
Commercial flower crops
Cockatoos can damage commercial flower crops by pruning bushes and removing flowers. Limiting nearby food sources, or moving the birds from local roost sites may help to reduce losses. If the birds are discouraged from roosting nearby their pruning behaviour may be directed elsewhere. The scaring and shooting program outlined above can be used for moving birds from a roost site. Visual screens made from shade cloth or other material 2-2.5 m high can be used to deter cockatoos from entering the crop. Screens can be especially effective for protecting seedlings.
At the crop site a combination of scaring and shooting, using bird hides, Bird Frite® cartridges, taped alarm calls and gas guns, may be effective. If only a small number of birds are involved destruction may be useful and cost-effective, provided there are no food or roosting attractions in the area that continue to draw more birds in. Flower growers should record and assess all losses caused by cockatoos and other birds to determine whether major exclusion projects like netting will be cost-effective.
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.”
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.
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.
Successful damage control programs
Not all of the damage control measures outlined in this note will be effective in all situations. Cockatoos are highly intelligent. However, a control program that:
- is carefully planned;
- is based on an understanding of cockatoo behaviour;
- is varied frequently;
- reinforces scaring stimuli with some killing;
- integrates a number of different measures; and
- is persistent;
has great potential for success.
The role of bird destruction
There is no evidence to support the view that a substantial reduction in the general population of Long-billed Corellas, Sulphur-crested Cockatoos and Galahs in Victoria would be effective in controlling localised damage.
Control of specific flocks as part of a larger, integrated strategy with diverse, mutually reinforcing bird damage control measures, may be appropriate where individuals have severe damage problems.
Several things need to be considered before killing birds:
- killing birds is pointless if it does not lead to a reduction in the damage being caused;
- killing birds should not be undertaken if it costs more than the damage being caused;
- killing birds is usually only a short-term measure, and is unlikely to have much impact on the overall population size or its ability to recover to former numbers: its main aim is to affect behaviour by causing large flocks to disperse;
- some destruction methods bring people into close contact with cockatoos. These people risk catching the disease chlamydiosis (psittacosis) if they inhale feather dust. Protective measures should be taken.
Destruction of birds may result in a short-term change in behaviour. But this can also be achieved at less expense by other means, such as using decoy food, scaring, or making visual barriers.
Further information
- Contact the DSE Customer Service Centre on 136 186 for further information.
Services and equipment
Gas guns
E.E. Muir,
542 Footscray Road
FOOTSCRAY 3011
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.
Taped alarm calls
E. Thomson
03 9846 1173
Tapes and CDs of Sulphur-crested Cockatoo and Long-billed Corella calls available. $15.00 plus p&p.
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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