Bird control on buildings

Over time human kind has come to encroach on the habitat of wild birds. As a result they now inhabit our towns and cities in increasing numbers. Whilst in some ways they enhance the urban environment, if uncontrolled they can cause serious damage to buildings.

Types of bird post
Any bird can be considered a pest if it is damaging a building, but the main species causing problems are:

• Pigeons

• House Sparrows

• Seagulls

• Starlings

It is important to identify what species of bird is causing a problem before finalizing a strategy to control it. For example, mesh suitable to prevent a sea gull from gaining entry to a building would not be effective in controlling access by house sparrows. Some forms of sonic deterrent are also species specific.

The problems birds create
Birds can cause problems in a variety of ways:

• Droppings can leave stains on the exterior of walls and roofs. This has a negative impact on the visual appearance of buildings and can initiate decay mechanisms.

• Feathers, droppings and dead birds can block rainwater goods, leading to a variety of related problems.

• Nests and droppings can act as a breeding ground for bacteria and insects posing a health risk to the occupants of buildings. Birds can also be carriers of disease.

• If birds are allowed unhindered access, the build up of guano and other matter inside a building can be considerable.

• Bird droppings are acidic in nature and, as such, can cause long term deterioration. On reaction with water this can produce a mold which can attack masonry. Bird droppings are also highly corrosive to metal, and this can cause severe damage to statues and memorials.

• There is a potential allergen risk to humans which can cause respiratory and skin problems.

• Droppings can make pavements slippery and hazardous.

Net system
Netting strung across openings and over roosting sites to physically prevent birds gaining access. It is worth noting that bird netting comes in various mesh sizes so it is important to ensure that the appropriate size of mesh is utilized. Care should be taken not to allow fixings which may damage the building fabric and ideally fixings should be made in masonry joints wherever possible. Netting is effective in preventing birds from entering an area of a building but the downside is that it is visually intrusive.

Wire coil system
This is a similar system to bird spikes but uses protruding coils rather than projecting pins. It is therefore safer to use where children may have access.

Spikes
The installation of spike systems has become one of the most common deterrents in recent years. It consists of a dense pattern of pins attached to strips which are secured to ledges and other surfaces to deter birds from landing on them. This is a highly effective method but it can create a strange visual effect. One of the major advantages spikes have over many other deterrents is that, if installed correctly, they should be completely reversible as, for example, they can be cable tied to gutters and pipes. Unlike some other products, they also have a long life span.

Spring wire
Installed on flat surfaces this anti-perch device consists of vertical metal posts or eyes, through which wire is connected or passed. The system is less visually intrusive than spikes but can still pose problems for building owners. The posts or eyes have to be glued or, more commonly, drilled and cemented into the building fabric causing irreversible damage. Water can settle in the drilled holes if the eye or post is not completely sealed in place and this can cause further damage to the fabric of the building. Consequently, care should be taken when installing the spring wire system.

Decoys
Fake models of birds of prey are designed to scare off pest birds. A non-lethal alternative to employing actual birds of prey, decoys can be effective in deterring roosting. To ensure effectiveness they require to be moved periodically.

Gels
Designed as an anti-perch device, the use of gels on historic buildings is not recommended as they can cause considerable damage to the surface on which they have been applied. The gels are often oil-based and this tends to leach into porous masonry, visually disfiguring the residue is extremely difficult to remove.

Chimney pots
Where a chimney is not in regular use it is advisable to fit a chimney pot guard to prevent birds nesting there. These are inexpensive and easy to install provided access is available.

Closing gaps
To prevent birds gaining access into buildings it is advisable to close up all external gaps over 20mm in width. Where this is impractical there are a number of simple steps that can be taken to prevent birds gaining access. Sealing gaps under eaves and replacing fallen slates and roof tiles will help prevent access to roof space. This can be done by filling in decayed pointing, replacing lost or broken tiles and slates (both good maintenance practice anyway) or fitting specially designed eaves comb fillers. When preventing birds from gaining entry it is important not to fully seal gaps intended to provide ventilation. These should be fitted with guards that still allow air entry.

Poison
In the past poison has been used to control bird populations that have affected buildings. Its use is not recommended for a number of reasons. It can be dangerous to humans and can result in leaving dead birds and decaying carcasses in hard to reach places causing pollution and health hazards. The use of poison may also lead to a building owner breaching animal protection laws and is therefore not advisable.

Shooting
Shooting has also been used to control bird populations but, as with poisoning, it has significant drawbacks in addition to the risk of collateral damage. In many instances the dead birds can be left in inaccessible areas causing the same problems noted where poisoning was considered. There is also the danger that birds will only be wounded causing distress to them and to members of the public.

Sonic devices
Emitting high pitched noise, sonic devices deter birds from the area around a building. They are more effective for some species than others, and advice should be sought regarding which system suits a particular bird problem best. Although relatively expensive, it is one of the least intrusive methods of bird control available.

Birds of prey
The flying of birds of prey in areas with feral bird problems has become an increasingly popular method of control. The effectiveness of this method in the long term is only possible as a result of repeated visits. It is one of the least invasive techniques available.

Trapping
Trapping can be an effective means of controlling an excessive bird population. Once a certain number of birds are trapped in baited cages they are taken away and killed or released elsewhere. It is worth noting that where pigeons are trapped they may have to be destroyed due to their tendency to return to roosting sites.

Food sources
Removing food sources reduces breeding rates and discourages further migration of birds to an area. This can be addressed primarily by discouraging people from feeding birds, and the careful disposal of waste food. It should be noted that research into this topic indicate that all lethal methods of control have serious flaws and do not work in the long term. They only deal with the problem and not the cause. Non-lethal methods of control, which frighten birds off or remove areas of habitat or sources of food, are far more effective in the long run. It should also be noted that nesting birds are protected by the Wildlife and Countryside Act 1981 and it is illegal to tamper with a bird’s nesting site, or to take or destroy eggs. There are other legal restrictions on the control of certain species, and this should be ascertained before any action is taken. Listed building consent may also be required when introducing some of the physical forms of bird control. Dealing with bird pests is not an easy task. But, with thought, a solution can be found to minimize the risk to both humans and buildings. The aim is to do this in a manner that is sympathetic to both the birds and the buildings.