Problems Caused by Cockatoos (DSE Vic)

March, 1999 Problems caused by cockatoos LC0015 Ian Temby, Melbourne ISSN 1329-833X

This Landcare Note outlines the behaviour of cockatoos the effects of repeated insect attack in the absence of and the range of damage which may be caused by them. effective predator/parasite control systems. It subsequently discusses the principles of control. Generally, these cockatoos feed into a maturing crop from Cockatoo damage falls into 3 categories. the edges, so that it is clearly advantageous to minimise the amount of edge in a crop. Problem 1 If onion grass is present in the paddock to be cropped, its The sulphur-crested cockatoo, long-billed corella, little corms will attract cockatoos once the paddock is ploughed. corella and galah regularly cause damage problems in If the birds are permitted to become habituated to feeding Victoria. These include: damage to germinating and in that paddock on the onion grass, then once the crop is ripening cereal and sunflower crops; damage to almond sown, losses of sown grain can be expected. and walnut crops; damage to mature trees by pruning tips Long-billed corellas, sulphur-crested cockatoos and galahs off upper branches; damage to newly planted trees; are declared unprotected throughout Victoria, under damage to cricket pitches, golf courses, sports ovals and certain conditions. Where these birds are causing serious bowling greens by digging, usually for onion grass, damage to trees, vineyards, orchards, recreational reserves Romulea spp. corms; damage to co-axial cables. or commercial crops, they may be destroyed by landowners or occupiers, their employees and families and, Problem 2 in the case of recreational reserves, by members of the The sulphur-crested cockatoo can cause severe damage to committee of management. Destruction of these birds may timber in houses, in particular western red cedar window take place only on the freehold or leasehold property on and door frames, whether painted or not. They may also which the damage is occurring. Birds may be destroyed destroy rooftop polythene pipe water-heating systems. only by the use of firearms in accordance with the Firearms Act 1958. Problem 3 It appears that the sulphur-crested cockatoo is becoming Yellow-tailed black-cockatoos can ocasionaly cause more common in urban areas and problems are being damage to unripe seed stocks in pine tree seed orchards. reported more frequently from these as well as rural areas. A common factor contributing to house damage problems Background is the provision of food for the birds by a near neighbour. The beaks of cockatoos grow continuously and it is It has been suggested that many of the birds which cause possible that regular chewing is required to maintain beak this damage may have escaped or been released from length and condition. This could explain why co-axial captivity. cables, trees and houses are chewed by cockatoos. All of The yellow-tailed black-cockatoo, in common with the these cockatoo species, except the yellow-tailed black- other cockatoo species, has adapted to feed on a variety of cockatoo, feed to a greater or lesser extent on the ground introduced plants, in addition to its natural foods. One of and dig up much of their food. its frequent foods is the seeds of various species of pine When resting in trees after a period of feeding, or before trees. Birds may return to particular trees in successive setting out to feed early in the day, the sulphur-crested years. cockatoo and the corellas often bite off small branches from the trees they are roosting in, leaving the ground Possible solutions below covered in prunings. It is common for the same trees Problem 1 damage to be used for such roosting, often for months or years. This can lead to the decline of some trees. Many factors • Site crops away from trees and water. can be responsible for tree decline, and less obvious • Minimise the ratio of crop edge to area by planting influences than repeated pruning by cockatoos may also be crops in a compact shape, such as a square rather than a implicated. Such factors could include changed soil long, narrow rectangle. hydrology, soil compaction, altered soil nutrient status and

• Plan farm activities so that time will be spent near the Problem 2 damage crop during the susceptible period. • With damage to houses or rooftop water heating • Deter birds from feeding on the paddock to be cropped systems, determine whether any neighbours are feeding even before the crop is planted, to prevent a feeding the cockatoos and if so, point out the problems you are pattern becoming established. (Often the birds are having and suggest that they stop feeding the birds. attracted when the paddock is first ploughed because Add that reliance on foods put out by people could lead onion grass corms are exposed). Birds should be to dietary problems and that there is natural food deterred from feeding on exposed onion grass corms available to the birds. before crop planting, or grain should be direct-drilled • Exclude cockatoos using plastic bird netting, shade in such areas. An alternative strategy might be to cloth or wire netting to prevent access to susceptible eliminate onion grass with chemicals. Seek advice on timber or poly pipe; cover the timber with metal this from DSE. sheathing or stretch nylon fishing line across the • Plant the right variety of sunflower (or other crop) for normal flight path of the birds as they approach the the area, to promote even germination and a dense house. crop, since such crops are less prone to damage. • Use other timber for window and door frames. • Plant a screen of tall plants around, and in strips within, • Place scrap pieces of western red cedar timber in a cereal or oilseed crop as a visual barrier. Sorghum strategic positions, away from the house, as an has been used for this purpose. This creates insecurity alternative attraction for the birds. in cockatoos which are then reluctant to feed, or are more easily deterred, than if no visual barrier is • Make a swinging arm of wood approximately 40cm present. long, which pivots on a screw 3cm from one end. The screw is driven into the window frame and is a loose fit • Always combine deterrent strategies, where possible. on the piece of wood. When cockatoos land nearby, the Such strategies could include: provision of alternative arm can be raised by pulling on a nylon line, attached food such as feed oats or onion grass corms, exposed 2.5cm above the screw hole, which leads down through by ploughing, well away from the crop; gas guns; one or two screw-eyes and into the house. If you scarecrows; Bird Frite cartridges and frequent remain out of sight the cockatoos will not associate the patrolling in the crop. Note that the use of gas guns and sudden movement of the arm with humans and will be Bird Frite cartridges may not be acceptable in built-up wary of it. areas. Prior clearance from local Police and municipal authorities should be obtained before these devices are • Broadcast alarm calls as the birds arrive. These alarm used in such situations. calls should only be played for short periods, and have been effective in some cases. • Exclude birds from crops such as almonds using bird- proof netting. • Scare birds with Bird Frite cartridges, other loud noises or jets of water. Note that the use of gas guns and Bird • Control pruning of trees by cockatoos by persistent Frite cartridges may not be acceptable in built-up areas. scaring and plant more trees now or encourage natural Prior clearance from local Police and municipal regeneration to reduce the possible impact of this authorities should be obtained before these devices are behaviour in the future. used there. • Damage to tree seedlings may be reduced by leaving or • Destroy the bird or birds involved, under the conditions growing strips of tall grass either side of the seedlings, of an Authority to Control Wildlife. In urban areas, this as a visual screen. Alternatively, direct seeding may may involve cage-trapping and humane destruction by provide sufficient plants that some losses are not a veterinarian. important. Naturally germinated trees appear to suffer fewer problems from cockatoos than planted trees. Problem 3 damage • Determine what the cockatoos are digging for in cricket • NB No repellent compounds which prevent this pitches, etc., and eliminate this food source if possible. damage have yet been found. • Sheath co-axial cables with metal to prevent chewing. • To deter Yellow-tailed Black-Cockatoos, scare them • Destroy a small number of birds by shooting to with Bird Frite cartridges. enhance the effect of other scaring methods. This Commence scaring as soon as birds arrive to prevent a should not be seen as a substitute for instituting long- feeding pattern from becoming established. term controls.

Further information Refer to DSE Landcare Notes: LC0009 - Reducing cockatoo damage to crops LC0011 - Reducing cockatoo damage to stored fodder, ripening crops and feedlots LC0012 - Reducing cockatoo damage to tree, fixtures, houses, sports grounds and the environment LC0013 - Reducing cockatoo damage to fruit, nuts, grapes and flowers

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