Feral Birds

Angry Birds, painting that features a House Sparrow
by Carel Brest van Kempen
Feral birds are ones that have escaped from domestication and have managed to establish breeding populations in the wild. Feral populations are the results of accidents -- not of releases by people who intended to add new birds to the local fauna. A substantial proportion of exotic species that "get away" are doves, parrots and their relatives, and waterfowl, because of the popularity of these groups in the pet trade. In most cases, pet escapees (and those "given their freedom") have not gone feral. In the past two decades, however, several species of tropical and subtropical doves and parrots have managed to establish breeding populations in the United States.

Most of these localized populations are found in southern California and southeastern Florida, both because of their hospitable climates and because Miami and Los Angeles are major importation centers for the pet trade derived from Latin America
and from tropical Asia and Australia, respectively. The Mediterranean climate of coastal California and the subtropical climate of south Florida have also been conducive to the widespread introduction of exotic plants which create familiar habitats for exotic bird species.

Chief among our feral doves are the Ringed Turtledove and the Spotted Dove, both of which are well established in southern California. The turtledove is also feral in central and southern Florida, Houston, and Mobile. The Spotted Dove's range extends from Santa Barbara south to San Diego, and seems to be strongly associated with eucalyptus trees. In contrast to the Spotted Dove, which apparently was released intentionally at first, the Ringed Turtledove appears to have established itself through multiple escapes in and around the several cities it inhabits.

Parrots and parakeets have long been favorites with exotic-bird fanciers. There are probably a few escapees somewhere of every species of parrot imported into the United States. Rose-ringed, Canary-winged, and Monk Parakeets, Budgerigars, and several of the large Amazona parrots (especially the Yellow-headed Parrot) each now exist in small, stable, feral populations.

The Monk Parakeet illustrates the potential harm (real or imagined) that could be engendered by the establishment and expansion of a feral psittacine. The species is native to temperate regions of southern South America, so that unlike most parrots, it is not dependent on tropical climatic conditions. The Monk Parakeet was first reported in the "wild" in 1967; in the following three years, nearly 35,000 birds were imported legally into the United States. Numbers in the wild continued to increase, and by 1972 nesting Monk Parakeets were scattered across much of the East Coast and were found in locations as diverse as California, Nebraska, Oklahoma, Michigan, and Ohio.

The Monk Parakeet is considered a major agricultural pest in its native Argentina. That reputation, coupled with reports in the popular press putting the U. S. feral population at 4,000 to 5,000 birds, led to a coordinated eradication program, especially in New York, New Jersey, California, and Virginia. The program was highly successful, and small feral populations now persist only in a few Florida locations and in Chicago. In retrospect, the fears may have been groundless. The actual number of feral birds probably was overestimated considerably, and population expansion was mostly confined to the metropolitan New York area, with lesser numbers in Florida, Pennsylvania, and Illinois. Nonetheless, it has been estimated that the Monk Parakeet could cause millions of dollars in agricultural losses should it become abundant.

The fate of feral psittacines in the United States is more likely to be typified by the Canary-winged Parakeet, a tropical species from South America. From 1968 to 1974, more than 260,000 individuals were brought into the United States by the pet trade, making it the most common psittacine import during that period. Small feral populations have been reported in California, Florida, Connecticut, and New York. Ethologist Patricia Arrowood had studied the San Francisco population of Canary-wings for several years and reports that although breeding is successful each year, juveniles suffer inordinately high mortality rates. Nesting and roosting occur in (introduced) palm trees, and the birds feed primarily on buds, flowers, nectar, seeds, and fruit of mostly exotic species of trees. Winter survival is largely dependent on food supplied at backyard feeders. Although the birds are very conspicuous as they fly noisily over the rooftops between their nesting trees in Dolores Park, their primary foraging site on Telegraph Hill, and their nonbreeding-season roost in Fort Mason, their numbers remain stable at fewer than 20 birds.

The Canary-winged Parakeet appears to be more successful in south Florida, where nearly 700 birds were reported in a single winter roost in 1973. Black-hooded Parakeets (Nanday Conures), another tropical American species, have, however, replaced the Canary-winged Parakeet as the most popular psittacine import. It seems likely that they will become widely feral in the coming years, with the most successful populations in warmer areas.

Members of the parrot family are not the only cage birds to have gone feral in the mainland United States. Red-whiskered Bulbuls (passerines related to kinglets), from southeast Asia, escaped from a bird farm near Miami around 1960. The species, at last report, occupied about three square miles and was slowly spreading. Escaped bulbuls also established feral populations in the Los Angeles area, where attempts have been made to eliminate them by shooting. The Java Finch and Indian Hill Myna, both popular as pets, are also feral in the Miami area. The Spot-breasted Oriole from Central America is also well established in southeastern Florida following escapes from captivity. The most spectacular feral bird in the United States, however, is the Greater Flamingo. This Caribbean species has repeatedly escaped from captive flocks in Florida, and a free-flying colony lives around Hialeah Race Track in Miami.

The establishment of feral birds is, by definition, unintentional. Some birds, of course, have been deliberately introduced into North America. They fall into two categories: game and nongame species. Several game birds, such as the Ring-necked Pheasant, Chukar, Black Francolin, and Himalayan Snowcock, have been released by fish and game departments for the express purpose of providing recreational hunting, and are now well established as breeding populations. Introductions of nongame species for a variety of ill-considered reasons include the European Starling, House Sparrow, Eurasian Tree Sparrow, Crested Myna, and Eurasian Skylark, of which the first two species have become widespread, major pests.

Feral birds, like the European Starling, always have the potential of harming native species. Monk Parakeets have been reported killing Blue Jays and a robin, but there is no documented case of serious interference with natives. So far we have been lucky, but unless the pet trade is carefully controlled, that luck may run out.
SEE: Avian Invaders; Birds and the Law.
Copyright ® 1988 by Paul R. Ehrlich, David S. Dobkin, and Darryl Wheye.