Many escaped from cages, whereas others were brought over to be hunted, to beautify the landscape, or in ultimately futile attempts to control insect pests. One infamous case involved William Shakespeare.
But although the reasons behind them have changed, avian introductions into the United States have been a constant occurrence since well before the founding of the country. Including Hawai’i, as well as species that have been transplanted across state lines, like House Finches and Wild Turkeys, there are now over 100 non-native U.S. species believed to have self-sustaining breeding populations (plus a plethora of less-established feral species).
The first to arrive was likely the Red Junglefowl, the primary ancestor of the domestic chicken, sailed to Hawai’i by Polynesian settlers several centuries ago. Ever-present Rock Pigeons joined the fray in the 1600s, when French and English settlers purportedly introduced them to Nova Scotia, Massachusetts, and elsewhere.
A trickle of exotics then crested into a wave in the second half of the 19th century, starting around 1851, when House Sparrows were initially released into Brooklyn, New York, possibly in a failed bid to control caterpillar outbreaks. Mute Swans and European Starlings soon followed; the latter was imported in 1890 by a pharmaceutical manufacturer who hoped to bring over every species mentioned by Shakespeare.
Private organizations and individuals facilitated myriad other bird introductions as well. The Cincinnati Acclimatization Society alone released some 20 species in the 1870s. But these birds mostly died off, and the practice eventually fizzled out.
By then, though, a new phase of introductions had begun: game birds. The Ring-necked Pheasant, for instance, was first successfully introduced in Oregon in the 1880s by a U.S. diplomat. (Previous stabs at establishing pheasants, including by George Washington at his Mount Vernon estate, had flopped.)
Post-World War II, the U.S. Fish and Wildlife Service got into the act, releasing, at the behest of hunters, at least 32 foreign game species between 1948 and 1970. “Most of their attempts failed,” says Stanley A. Temple, a professor emeritus in conservation at the University of Wisconsin-Madison, who co-authored a Congressional report on non-indigenous species in the 1990s. “But there’s still a large number…that have breeding populations.”
These days, the importation of wild birds from overseas is strictly regulated, and exotic releases are generally frowned upon. Yet the number of non-native species in the United States continues to rise because of avian fugitives.
Whip-smart with powerful and versatile beaks, parrots are especially adept at busting out of cages and aviaries — that is, when not being let go by owners fed up with their noisy calls. No fewer than 56 parrot species have been spotted in the wild since 2002 (only nine of which are currently considered countable by the American Birding Association). “Some of my friends in California have a diversity of parrots showing up at their bird feeders,” Temple says, adding that “you don’t have to look very hard in Florida to come up with ‘Amazon’ parrots.”
All these parrot species have restricted ranges. Not so, however, the Eurasian Collared-Dove, which arrived in Florida in the early 1980s via the Bahamas, where a few dozen had allegedly escaped following a pet store robbery in the mid-’70s. Since then, they have expanded as far as Alaska.
Ironically, even as the number of non-native species goes up, some of the more established exotics, such as House Sparrows, starlings, pigeons, and pheasants, have sharply decreased in number, presumably due to the rise of industrial agriculture. “If you had to generalize,” Temple says, “you’d say the changes in agricultural practices have not been good for birds, whether native or non-native.”
Though fun to look at, non-native birds have undoubtedly taken a toll on both humans and wildlife. They eat crops, disperse weeds, occasionally down airplanes, and, in the case of Monk Parakeets, short-circuit electric utility facilities with their massive nests. In fact, scientists estimate that introduced birds cause roughly $2 billion in damages annually just in the U.S.
Moreover, House Sparrows and European Starlings tend to evict or even kill native cavity nesters. Non-natives also potentially spread diseases to native birds, outcompete them for food, and, at times, hybridize with them. For these reasons and more, most experts strongly oppose the release of any exotic.
Yet, unlike with non-native mammals, insects, and reptiles, all of which have directly caused bird extinctions worldwide, non-native birds don’t appear to be wreaking complete havoc.
“Except possibly for Hawai’i, I know of no cases in which an introduced species of bird…has had a significantly detrimental effect on a native bird species,” says Walt Koenig, a visiting fellow at the Cornell Lab of Ornithology, who has studied the impact of starlings and Eurasian Collared-Doves on the local fauna. “It doesn’t seem impossible, but I just don’t know of any good examples.”
At any rate, eliminating them would be essentially impossible. For better or worse, starlings and their non-native brethren are here to stay.
This article first appeared in the November/December 2021 issue of BirdWatching Magazine.