Many people are surprised to find birds causing problems on buildings in urban areas, but birds are actually very common in cities and many species may potentially create problems on buildings. Fortunately, by understanding the birds that most often cause problems, as well as the architectural features that attract them to buildings, nuisance bird problems can usually be addressed by making the building less attractive to the birds.
While any bird can potentially cause a problem on buildings, most problems in American cities are caused by three bird species introduced from Europe—pigeons, starlings, and house sparrows. These birds adapted to living in European settlements and cities for thousands of years, and found an easy life living in and around our buildings when first brought to America in past centuries. Early colonists first brought pigeons to America as a food source, while 19th Century enthusiasts brought over starlings and house sparrows in a misguided effort to control caterpillars (house sparrows) or introduce to America all the birds mentioned in the works of Shakespeare (starlings). All three of these species readily eat discarded human food and nest on buildings—making them the perfect urban invaders. In addition to these non-native birds, a few native birds may cause problems, especially when large numbers congregate on rooftops (crows, gulls, and occasionally vultures) or nest on exterior walls (swallows). In fact, birds that are urban invaders do so well that there are usually more individual birds per square mile in cities than in the countryside!
What attracts birds to buildings?
Birds need food, safety, and nesting sites. Birds are attracted to buildings that are able to provide those needs and identifying what is attracting birds to a building is the first step in solving any given bird problem.
Food– Garbage bins, restaurants, retail stores, warehouses, and food processing plants may all attract pigeons, starlings, house sparrows, gulls, crows and other birds that scavenge human food. Blocking access to food sources and making sure trash containers remain sealed and any food wastes are quickly cleaned up and removed is the easiest way to eliminate this attractant.
Safety—When birds aren’t nesting or looking for food, they are usually resting and they need a safe place to do that. Rooftops and ledges are high areas that are safe from cats, dogs, and other predators on the ground and provide a good lookout for intruders and other threats. Gulls, crows, pigeons, grackles, and other birds may congregate during the day or roost on buildings for safety at night. Often a mall or other large building complex separated from woodlands or other habitat by extensive parking lots is considered an ideal night roost by birds trying to avoid owls or other nocturnal predators. If birds are loafing or roosting on a building, the best way to eliminate the problem is to put up physical barriers such as bird spikes, wires, an electric jolt track system, or some other barrier to make it physically impossible for the birds to use the area. While it is usually preferable to install a physical deterrent system, if that isn’t possible or feasible, the area can be made less attractive by installing a sonic system or visual deterrents that can scare the birds. Large persistent roosts may need to be dispersed by a licensed wildlife professional. Buildings such as stores and warehouses that are not completely sealed may attract house sparrows or other birds that find the protected building interior safer than the outdoors. Whenever possible, buildings should be sealed to prevent bird entry, and birds that do enter should be trapped or netted and removed.
Nesting—pigeons, starlings, and house sparrows prefer to nest on buildings. Pigeons frequently nest on protected window ledges or under rooftop equipment, while starlings and sparrows nest in pipes, gutters, vents, or other small openings in a building. Ledges should be covered with spikes or altered with a bird slope or other retrofit to eliminate the flat surface so that pigeons cannot roost or build a nest. All vents or exterior holes and nooks should be sealed with netting or some other barrier so that starlings and sparrows can’t gain entry to build their nests. Barn swallows may build nests in open warehouses or other buildings, while cliff swallows may build nests on exterior building walls. These native species are protected by Federal laws, so nests with eggs or babies may not be tampered with. Remove old nests after they are used, or prevent birds from initially building nests by using netting or other barriers that keep the birds from being able to build their nests.
Solving bird problems on buildings
Once you have determined what bird you are dealing with, and what seems to be attracting the bird to your building, the first thing to look at is if there is a way to physically stop the birds from landing or nesting where you don’t want them. Search for a physical deterrent that can best address the size or type of birds you are dealing with, and the exact structure you are trying to protect.
If there isn’t a physical way to keep the birds off or out of your building, then you have to resort to behavioral controls that try to scare the birds away. These can be visual devices or a sonic system, though recognize that if a bird is attracted to your building, the attraction may be stronger than any real or imagined threat that you may present to the bird. Note as well that sometimes if birds get used to seeing or hearing bird control devices without seeing a real threat, eventually they won’t be scared of them anymore and you’ll have to try another approach.