Birds and their control in non-agricultural environments
Birds of all species are normally welcome in non-agricultural environments, as they are elsewhere. However, there are occasions when they cause problems. The accumulations of bird droppings can, for example, pose a risk to public safety and health, hygiene standards may be compromised in food premises, and paths and walkways may become slippery and unsafe. Birds may also sometimes act as a reservoir for disease. In deciding on the measures to take in response to such problems, it is important that all legal and practical implications are considered.
Bird species and problems
The species that most frequently cause problems are feral pigeons, house sparrows, and starlings; however, in certain coastal areas, herring and lesser black backed gulls can be responsible for damage and, in parks, Canada geese. Nationally, starling and house sparrow populations have declined significantly in the last few years and problems caused by these species are now less frequent. Occasionally, species such as blackbirds, robins and wagtails cause problems when they gain access to food premises.
Flocks of pigeons typically congregate on buildings, and this may result in a build up of droppings. These create hazardous walking surfaces, particularly in wet weather. Droppings may also contaminate foodstuffs and other products. Nest materials and other debris collected by the birds may block rainwater drainage systems and can encourage infestations of insects and mites. There is also a human disease risk from direct contact with the birds.
Sparrows can frequent food preparation and storage areas such as bakeries, factories and warehouses. They often live within the buildings where they may contaminate products with faecal and nest materials. Even packaged food such as flour, biscuits and cereals may be damaged; this stock may have to be discarded so as to avoid supplying customers with contaminated goods.
Large flocks of starlings often roost at night in urban areas, using trees, buildings, or structures such as bridges and towers. The sheer amount of droppings together with their chemical action can damage and kill trees and any vegetation underneath. Fouling can lead to unsafe paths and walkways and result in contamination of equipment and structures.
Herring gulls, and occasionally, lesser black-backed gulls roost and nest on buildings near the coast. They may become aggressive, particularly when incubating eggs and rearing young. This protective behaviour can result in attacks on members of the public in the street or on those needing access to roofs for maintenance purposes.
Nest materials may block gutters and down-pipes, and provide an environment in which insect and mite infestations can develop. Droppings contaminate equipment and may make access routes slippery. Discarded food previously scavenged from rubbish tips or other sites can encourage flies.
Canada geese can cause problems in urban parks and gardens by grazing, trampling, fouling footpaths and damaging wildlife habitats. A booklet entitled "The Management of Problems Caused by Canada Geese – a Guide to Best Practice" (code: 99 WACD 0520) is available from the Department for Bird control in non-agricultural environments RDS WM13 Published February 2003 2 Environment, Food and Rural Affairs (Defra) (for address see under ‘Further information’).
All wild birds and their eggs and nests are protected under the Wildlife and Countryside Act 1981; under this Act birds cannot be taken or killed, nor their eggs or nests (when in use or being built) be taken or destroyed except under licence.
However, it is recognised that a number of common 'pest' species (eg. feral pigeons, starlings, house sparrows, herring gulls and lesser black-backed gulls) may frequently cause problems. Natural England issues a number of general licences which allow authorised persons (ie.. an owner or occupier) to control numbers using certain specified methods. These methods change from time to time so check www.naturalengland.org.uk for the latest information.
Nests not being built or not in use are not protected under the 1981 Act and may be removed or destroyed at any time. Action is permitted under these general licences to prevent the spread of disease, and for the purpose of preserving public health or public or air safety.
Separate licences may also be issued by Natural England, for example to control Canada geese in parks for the purpose of preserving public health or safety, or to permit the use of stupefying baits (see 'Population control').
The 1981 Act does not allow action against birds or their eggs or nests for the purposes of preventing damage to property or preventing nuisance problems; such problems include noise, smells and the triggering of intruder alarms by birds flying within buildings. These can only be tackled by using non-lethal methods of control, for example, scaring and proofing.
Before deciding on a specific course of action, the extent and nature of the problem should be carefully considered. The aspects that need to be addressed include:
- the species and number of birds involved;
- the level and type of damage or problem being caused;
- the buildings, structures or areas which are affected;
- any specific limiting or influencing factors that may affect the action proposed.
Management options fall into three broad categories:
1. Environmental management
A build-up of bird numbers in urban environments is normally a result of the presence of a readily accessible food supply and/or the availability of attractive habitats where they can roost or breed. Effective long-term management is normally dependent on the ability to eliminate or reduce these aspects.
In urban areas, this can be difficult because numerous occupiers and individuals may have some degree of responsibility for the cause of the problem or may be affected by it.
The single most important factor is the ability of the birds to gain access to a regular supply of nutritious food. If this can be denied them, then problems may be resolved without recourse to other measures.
Consider the possibilities for:
- avoiding the spillage of foodstuffs;
- keeping food storage areas secure and bird-proof;
- ensuring that disposal and waste facilities are kept clean and tidy;
- limiting or preventing the deliberate feeding of birds by the public or site staff.
2. Anti-roost and proofing measures
Birds can be prevented from entering or roosting on buildings by either installing netting over vulnerable areas or fixing wire, plastic or other purpose-designed devices to deter birds from landing on ledges, window sills or other structures.
The fitting of proofing and deterrent measures can be complicated, and is usually carried out by experienced operators. Correctly installed, these measures can provide a long term solution to bird problems. If inappropriate techniques are used, they may fail to exclude or deter the birds. For example, most anti-roost devices do not work effectively against starlings, and the mesh size of netting must be suitable for the species involved.
Attempts at scaring birds in urban situations using conventional visual or audible scarers are generally neither effective nor practical. Although there are a number of electronic devices on the market for which claims of bird deterrence are made, only the appropriate use of recorded distress calls of specific species, such as starlings, is likely to work.
3. Population control
Attempts at resolving problems by reducing or eliminating local bird populations are usually unsuccessful. This is because it can be difficult to achieve a sufficient level of cull and the problem often re-occurs when other birds are attracted into the cleared area. In addition, there may be significant opposition from employees and the public.
However, population control can play a useful role in some situations, for example, where a small, discrete group of birds needs to be removed, or when a limited reduction in the local bird population provides a satisfactory solution.
Options include egg control, cage trapping, shooting, mist netting
Egg control may be used in some situations to limit population size and reduce the rate at which bird numbers increase.
- Eggs can be removed and destroyed. However, birds often re-lay a removed clutch, so it may be more effective to encourage the birds to continue to incubate eggs made nonviable by treatment with liquid paraffin
- An advisory leaflet on the use of liquid paraffin (WM6) is available from Defra. General licences are issued by Natural England for certain species (under 'Legal Aspects'). If the species causing the problem is not listed on the general licence, Natural England should be approached for a separate licence.
- Cage trapping is predominantly used against feral pigeons and, to a lesser extent, house sparrows. Birds are encouraged to enter a trap by the use of attractive baits. The availability of suitable trapping locations is essential. Traps need to be serviced regularly and all captured birds must be despatched humanely. General licences are issued by Natural England for certain species (under 'Legal Aspects').
- Shooting is usually restricted to the use of a .22 air rifle. This method is often used either to remove feral pigeons from roost sites or to cull house sparrows causing problems in food premises. Safety considerations and legal constraints need to be taken into account. General licences are issued by Natural England for certain species (under 'Legal Aspects'). The use of a spotlight at night in conjunction with shooting is covered for certain 'pest' species by a general licence. Control of birds, such as blackbirds and robins in food premises, must only be undertaken by trained operators under a separate licence from Natural England.
- Mist netting is generally restricted to food premises, with house sparrows being the target species. The technique must only be undertaken by trained operators under a separate licence from Natural England.