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.