Now they are one of the most noticeable birds in American cities and farming communities. Countless thousands are still reared annually by pigeon fanciers who use them for homing and racing competitions, and each year the feral population is supplemented by captive-reared individuals that fail to return home. Rock dove populations were ignored by scientists and bird watchers before the Breeding Bird Survey began in 1966 and were not reported on Christmas Bird Counts until 1974. Introductions of several other dove species have been successful locally, especially in the mild climates of Florida, California, and Hawaii, but these species are not sufficiently widespread to be monitored by existing surveys. Small populations are established in southern California, eastern Texas, Florida, and Puerto Rico.
Occasional individuals occur each year in more northern states.
Its rapid spread across Europe in the past few decades suggests its potential for rapid expansion in America. Parrots Many species of parrots imported for the cagebird trade have escaped, especially at ports of entry. Control measures have eliminated most populations of this exotic species in the United States. Fewer nest on the U.S. mainland. The two most notorious species that dominate the environment and have negative effects on native species are the house sparrow and European starling, both of which compete with native birds for nesting cavities.