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Notes on Bird Control Introduction The presence of birds is usually welcomed, as they are indicative of a diverse environment and aesthetically pleasing to most people. However, in urban environments when large populations of certain species are present, serious problems can arise from fouling caused by bird droppings. These can be corrosive to building materials as well as presenting a public health threat. Additionally, in some residential situations, birds present a noise problem to local inhabitants. Most wild birds are protected under the Wildlife and Countryside Act (1981) but certain pest species can be destroyed, although this may require a permit or licence. The killing or removal of birds from an area is seldom an effective means of control as it creates a ‘vacuum’ into which other individuals will readily move. Destruction of birds is a difficult control method to implement and is usually only used as a last resort or, occasionally, to remove particular problem individuals from an area. Problems with urban bird populations are always made worse by the habit of many members of the general public of bird feeding. Often if the individuals involved can be encouraged to abstain from this activity the problem will go away. Usually, pest controllers will have to accept the presence of birds in an environment and use a number of proofing techniques to keep them away from sensitive areas where their droppings cause corrosion or could harm the public. The main species causing urban bird problems is the feral pigeon. This is a variety of the wild rock dove (Columba livia), the ancestor of the domestic pigeon. From time to time other species, notably starlings (Sturnus vulgarus) and house sparrows (Passer domesticus) may need to be controlled. Bird Proofing Indoors The best method of controlling bird problems inside buildings is to keep them out in the first place. Total bird proofing can be achieved by sealing all holes and openings greater than 20 mm in diameter. Plastic strip curtain should be deployed on doors that need to remain open for long periods; these should be allowed to hang freely and must touch the ground. Other doors should be fitted with self-closers to avoid them being left open. Corrugated panels and gaps under eaves must be filled using mortar, proprietary pre-formed foam sealing strips or an expanding foam and wire mesh preparation. The wire mesh will give added protection as birds may try to gain access by pecking at the softer expanded foam.
Ideally all windows should be kept closed but where ventilation is required, some form of proofing of the open window is essential. Netting systems Polythene or polyester woven netting can be used to exclude birds from areas such as light wells, ornamental building frontages, eaves, roof spaces and underneath bridges. Netting of an appropriate colour should be chosen for each application to ensure that the nets are virtually invisible from ground level. A net which retains its plasticity when exposed to UV light (i.e. is durable) and of the correct mesh size must be chosen.
The system is used principally to exclude 3 species of bird and is available in different sized mesh to account for their varying sizes: feral pigeon (Columba livia) (38 – 50 mm); starling (Sturnus vulgaris) (28 mm); and house sparrow (Passer domesticus) (20 mm). Naturally, the smaller size mesh will also keep out the larger birds but it is more expensive and often requires greater maintenance. Care should be taken to ensure a close fit of the netting to the building’s surface. If birds can gain access down the sides of the netting they will become trapped, often causing public concern as they cannot get out, and a health hazard after their death due to dehydration or starvation. Anti-perching systems It is seldom possible to protect exposed edges and gable ends of buildings from perching or roosting birds using nets. Therefore some sort of anti-perching system that prevents birds alighting on these parts of the building is required. Pin and wire systems, principally aimed at preventing feral pigeons from resting and roosting on ledges, work by making the surface uncomfortable for the birds. A spring-tensioned stainless steel wire is supported by a number of stainless steel posts drilled into or fixed on top of the masonry. As the birds attempt to land, they are either repelled by the wire pressing against the breast or, if they attempt to land on the wire, they are unable to stand due to the springing and flexing motion of the wire. Pin and wire systems are also effective against some other large birds such as magpies and sea gulls but they are not effective against smaller species such as house sparrows and starlings. The system can be used on window ledges, roof ridges, chimneys, gutters, gable ends and other architectural features. An alternative is the plastic strip ‘spike systems’. These comprise a plastic base into which are fixed stainless steel upright spring wires. The principle is similar to pin and wire systems. The birds are unable to gain firm footage and are repelled by the spikes. The spikes are available in several different styles, which ensures that there is a configuration suitable for every need. The bases can be plugged into the masonry or attached with a silicone glue where drilling is unsuitable or undesirable. This system is simple to use and is often more suited to smaller sections of ledge or when treating ornamental features and irregularly-shaped areas. With the pin and wire system, two or more runs may be needed to protect a ledge whereas variations of spike systems are available with multiple runs. If installed correctly these structures should be virtually invisible from ground level. Bird Scaring There are a number of products on the market that profess to scare birds, either visually by imitation of a predator such as an owl or hawk or by using random sound and/or light. Most of these will work well for a short period before the birds habituate to their presence. However, they can be useful to rid a premises of birds prior to proofing. Probably the most successful bird scaring method is to play a tape of the distress calls of the target bird species. These are effective for those species that possess the social structure of distress calls (starlings, gulls, jackdaws, rooks and blackbirds) because the birds respond automatically to their own flock distress signals, no matter how many times they are heard. Sadly, no distress calls have been isolated for house sparrows and feral pigeons. Bird Removal On a small scale bird removal is seldom an effective means of control, as a "vacuum" is created which will quickly be filled with birds from adjacent areas. Attention should be focused on removal of the source of the problem (e.g. spillage, open skips etc). Only then will the incidence of bird pests reduce. On a large scale however, a reduction in bird numbers by culling is sometimes necessary - populations of feral pigeons in large urban conurbations are an example. Conditions for feral pigeons in large towns and cities are often artificially good, as so many people feed them, allowing more than the natural carrying capacity of the area to survive and breed. Bird removal under these circumstances is the only solution, although it is likely to be on an-going annual or bi-annual activity. An array of methods are available to pest controllers to kill/remove birds but, because of the sensitive nature of this action, they are strictly regulated. Trapping Modern cage traps usually consist of an open wooden or wire frame covered in wire mesh, into which have been formed cone entrances. Birds are usually enticed using either a previously caught specimen bird or by pre-baiting/baiting of the area and trap with grain or a similar foodstuff and the cone entrance acts as a non-return device. It is a legal requirement that birds are caught alive; non-pest species can then be carefully released and the remaining birds can be humanely dispatched. Traps must be visited at least daily to release or cull birds. This is best done at dusk, after which no birds will enter until dawn. Food and water must be available in the trap to prevent undue stress to captured birds. Trapping can remove large numbers of birds but has some disadvantages. Pre-baiting tends to attract additional birds from outside the area prior to trapping and traps must be kept out of site of the general public. The sight of trapped birds will often cause adverse reaction, leading to damaged or removal of the traps, complaint, and sometimes physical threats and violence. Stupefying Baits The use of poisons and stupefying baits against birds is prohibited under the Wildlife and Countryside Act 1981 but, under special circumstances, a licence can be issued by the Ministry of Agriculture, Fisheries and Food (MAFF), the Secretary of State for the Environment or the Nature Conservancy Council. This method of control is mainly used against house sparrows and feral pigeons, although in some areas, licences may be issued for the control of gulls. A suitable bait (grain, cake etc) is treated with the stupefying chemical and placed where the birds feed. A period of pre-baiting may be advisable to encourage regular feeding. The birds eat the treated bait and become stupefied - it puts the birds to sleep. Pest bird species can then be humanely dispatched. Any non-pest species affected must be kept warm to encourage recovery, when they can be released unharmed. The drug usually used is alphachloralose. While this is readily consumed by the birds (there is no avoidance of treated bait) it is rather slow-acting. Sparrows are affected in approximately 15 minutes; pigeons can take anything from 20-50 minutes to succumb - and as a result they can sometimes move away from the baiting site, especially if disturbed, only to fall from the sky later on. In order to prevent this, a barbiturate seconal (quinalbarbitone sodium), is sometimes added to the bait to quicken its action. Alphachloralose/seconal mixes can only be used against pigeons. Stupefying baits can be very successful when used correctly but care needs to be taken not to antagonise the public. On completion of the treatment all bait must be removed and disposed of safely. Shooting Shooting for urban bird control should be a last resort. Firearms are especially dangerous in built up areas and the noise they generate scares other birds and attracts attention from the public. However, under certain circumstances, or where individual birds need to be removed, shooting can be the best option. Technicians must be conversant with the law relating to firearms and have a good understanding of the weapon, the ammunition and, above all, gun safety. Additionally, they must be trained and competent shots, to ensure a good quick kill, avoid wounding birds, minimise damage to property and the chance of ricochets. Weapons commonly used include 0.177 and 0.22 calibre air pistols, 0.22 calibre rifles and shotguns of 0.410 and 12 bore. Guns and gun holders must be licensed and, in urban areas, it is a good idea to inform the local police of your intentions before carrying out a shoot. Dead birds must be searched for and disposed of by burning or burial. Protected birds can only be trapped, shot or poisoned in Australia in accordance with appropriate licencing issued under various state and federal legislation. Origin: Killgerm
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