Birds in an urban environment can be serious pests, damaging historic buildings, interrupting church services, invading superstores, spreading disease and on occasion terrifying children. Feral pigeons, gulls, Canada Geese, tits, starlings and lapwings are considered particular problems.
Cathedrals and supermarkets with high and open roof areas have particular problems with bird pests. The construction of nests can damage buildings as can bird dropping. The Leaning Tower of Pisa is plagued with bird pests, harassing visitors and occasionally giving them a dose of food poisoning or a respiratory illness.
Economic losses caused by large roosts of starlings, pigeons and sparrows on buildings have not been fully estimated but they are of considerable economic significance in many cities. In Washington DC, for example, sizeable expenditures are now being made to bird-proof many of the public buildings, such as the Treasury, Capitol, and Supreme Court. This is accomplished by installing a low-voltage electrical system on building ledges that serve as roosting sites.
Large corporate office sites in suburban areas have provided ideal settings for some bird species, such as Canada geese, which have proliferated. In New Jersey and southern New York the number of Canada geese has grown from just a few a decade ago to 90,000. The result for human residents has been increased sanitation problems caused by the goose dropping.