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.