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Reducing cockatoo damage to trees, fixtures, houses, sports grounds and the environment | LC0012 |
Ian Temby, Flora and Fauna Branch
September, 2003 |  |
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This Landcare Note discusses options available for damage control and noise control.
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:
roost trees
planted tree seedlings
fixtures - aerials, light fittings, power lines, etc.
soft timber on houses and outdoor furniture
bowling greens, ovals, golf courses, etc.
In some cases, these problems are merely a nuisance; in others, serious damage can be caused.
This Landcare Note also covers cockatoo noise problems and cockatoos and biodiversity. 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
Roost trees
Cockatoos damage roost trees through excessive pruning. Roost trees can be protected by reducing the amount of time cockatoos spend in them. Roost tree damage is more common at day roosting sites than night roosts. The best results come from a combination of Bird Frite® cartridges and taped alarm calls, reinforced by some shooting, as the birds return 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. It should be noted that tree damage can have many causes, other than cockatoos. These include defoliating and sap-sucking insects; raised nitrogen content of soils, (especially where stock camp under trees); altered soil hydrology through soil compaction, or rising watertables; browsing by possums; fungal attack; and damage to roots by hoofed stock or machinery. Tree pruning by cockatoos, while visually obvious does not always result in long-term damage.
Planted tree seedlings
Cockatoos uproot or snip off newly planted tree seedlings. Visual screens can be used to reduce cockatoo damage to tree seedlings. One form of visual screen is to plant or leave strips of vegetation such as long grass on either side of the tree seedlings, and across it at intervals.
The screens should be 0.6 to 1 m high before the tree seedlings are planted. For small area plantings, fences of hessian or shade cloth can be used. The effect of these screens can be enhanced by some patrolling combined with shooting if necessary. Effective weed control is important when using this system.
Direct seeding is another way of reducing cockatoo damage, as is natural regeneration. Advice on direct seeding and natural regeneration is available from the Department of Natural Resources and Environment.
Aerials, light fittings, power lines and other fixtures.
Cockatoos perch on fixtures, where their chewing can cause significant damage. Powerlines to farm buildings can be run underground to avoid damage to insulation. Light fittings can be protected by building perches above them. Use 50 mm lengths of black poly pipe to encase the perches. When the birds land the pipe sections roll under their feet so they are unable to balance. To be effective the rolling perches should be the only perch sites on the fixture and should prevent birds from perching on the fixture itself. Commercially produced ‘spike clusters’ can also be used to prevent perching.
Black poly pipe can be used to prevent perching on the cross-sections of aerials. Sheathing communications cables in PVC or metal conduit reduces bird perching and damage. Loose roof nails should be replaced with roofing screws. Cockatoos are attracted to loose nails, the roofing screws remain firm.
Damage to fixtures can also be reduced by removing nearby food sources that are attracting the birds, or by scaring them from their roost sites and moving them on to other areas. In some cases bird damage can be avoided through the design and placing of fittings. Even existing fittings can be altered to provide better protection. Fine wires are difficult for birds to perch on. When they are stretched above a roosting structure fine wires can be an effective deterrent. In some cases using poly pipe 'rolling perches' provides the best protection.
Soft timber on houses and outdoor furniture
Cockatoos can damage timber fittings and furniture through chewing. This problem often occurs when someone is providing food for the birds and attracting them into the area. Try to find out who is feeding the birds and explain your problem. Removing the food source may be enough to move them on to another area.
Start a scaring strategy using alarm calls and loud noises. This can be difficult in built-up areas where you may also be disturbing neighbours. Timber can be protected with metal sheathing, or by hanging netting or shade cloth from the eaves on rollers. Roll it up, out of the way when you are home. When replacing western red cedar window frames and door frames use hardwood or metal. Consider excluding birds from very attractive areas with permanent protective screens or netting. Where damage is severe notify your local office of the Department of Sustainability and Environment (DSE) or the DSE Customer Service Centre on 136 186. You can also apply to DSE for an Authority to Control Wildlife (ATCW) to allow the trapping and humane destruction of the birds causing the damage.
A Licensed Wildlife Controller can be employed to trap and remove the offending birds. The DSE Customer Service Centre can provide contact numbers for controllers. .
Noise
Cockatoos are often very noisy at their night roost sites. Night roost noise lasts until after dark, and starts again well before dawn. Occasionally, there is an outbreak of calling during the night. Where roosting sites are near dwellings the noise can disturb local residents.
Birds can be moved from a roost by using a combination of Bird Frite® cartridges and taped alarm calls reinforced by some shooting. The birds should be scared as they return to the roost each evening. If the birds persist in returning to the roost site it may also be necessary to scare them at night with spotlights and Bird Frite® cartridges.
The birds should move elsewhere within a week of starting the program, but it could take longer. It is important to persist until the birds go. If the new site they choose is also unsuitable immediate scaring should move them on quickly. Be ready to scare at the original site if the birds decide to move back again. Department of Natural Resources and Environment staff can provide more details on carrying out a scaring program.
Bowling greens, ovals, golf courses…
Cockatoos damage sporting grounds by digging for Onion Grass corms or grass stolons. Try to work out why the birds are being attracted to the area and whether it is possible to reduce the attraction. If the birds are roosting nearby the scaring program described above will reduce the attractiveness of the roost site and encourage them to move on. Moving the birds out of the area can be an effective way of reducing damage to specific areas.
For relatively small sites, such as bowling greens, removable vertical screens of shade cloth 2-2.5 m high can be used when the greens are not in use. If the birds are attracted to Onion Grass try to remove it from the site. Bird hides can be used to reduce damage to golf courses. Birds are shot at from the hides with both live ammunition and Bird Frite® cartridges, combined with playing taped alarm calls. The hides should be moved frequently. Once the hides are in use staff can try to get closer to the birds and then shoot. Cockatoos are often unconcerned by golfers close-by, so staff posing as golfers, with a shotgun in the golf buggy will help to quickly make them wary of any golfer, after a short time. Any shooting must be undertaken with extreme caution, and only with clearance from the local police.
Impacts on biodiversity
Many people believe cockatoos can out-compete other bird species and are damaging to biodiversity. It is a common belief that Long-billed Corellas exclude other bird species from nest hollows. Careful observation shows that this is rare. Smaller species usually select hollows with entrances too small for cockatoos. Long-billed Corellas frequently nest in trees alongside a range of other species. There is usually little interaction between the species.
A more serious threat to biodiversity is the continued clearing of remnant bush, and the removal of live and dead trees from paddocks. The trees are crucially important habitat for a whole range of native species. Poor regeneration from remaining trees and bushland adds to the biodiversity decline.
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 can have great potential for success if it:
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.
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 barriers to hide fodder.
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
Raytrade Distributors, via your local ammunition dealer. Cost: $50.00 (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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