Introduced and Escaped Species

Joe Meche is vice president of the North Cascades Audubon Society and is in his ninth year as editor of the chapter newsletter. Joe is also a member of the board of directors of the Washington Brant Foundation. He has been photographing birds and landscapes for over 30 years and has been watching birds for more than 50 years.

On a recent trip to San Francisco, I was enjoying a first cup of coffee and watching the fog swirl in and out. Fog has a way of slowing everything to a virtual crawl and I was enjoying the quiet morning. Suddenly, my early daydreams were interrupted by a flock of birds that streaked past the large picture window. With the fog as a background, the birds appeared in silhouette and no colors were visible. My first thought was one of disbelief since the shape of the birds—approximately 20 in number—made me think, “Parrots!” When I mentioned this sighting at breakfast, my nephew reminded me of “The Wild Parrots of Telegraph Hill,” a book I had read a while back that documented the amazing story of these South American birds that have found a home in Tony Bennett’s “city by the bay.”

Needless to say, my interest was rekindled and the focus of that day’s activities included a trip to one of the famed San Francisco stairways—the Filbert Street Steps in the Telegraph Hill area. The east side of Telegraph Hill is home to as many as 160 red-masked parakeets (correct name), as well as a few mitred parakeets. As we descended the steps below the Coit Tower, we immediately began to hear the birds and saw numerous flyovers. When we reached the base of the steps, the parakeets were feeding in the bushes and shrubs, almost within arm’s reach! Although these birds seem to congregate around the Telegraph Hill area, they are known to forage in other parts of the city. While this was an interesting sighting in one of the country’s most interesting cities, this story has undesirable parallels throughout the country.

The origin of these particular parakeets is one of escape or careless releases by humans that date back as far as the mid-nineteenth century. Some introduced and escaped birds have established breeding populations over the past century, much to the detriment of indigenous species and migrants that breed in America. While the number of parakeets in San Francisco and their range might be limited by variables such as climate and available food, history has shown that this has not always been the case.

In the mid- to late-nineteenth century, European immigrants sought to improve their new surroundings by releasing familiar birds from their respective homelands. In one of the most egregious examples, an “acclimation society” was responsible for attempting to introduce all the species mentioned by Shakespeare into the New World. Eugene Schieffelin was the head of the society that released only a few pairs of European starlings into New York’s Central Park in the 1890s, and the results have had adverse effects on the birdlife of the entire continent. Since they were first released, starlings have become one of the most abundant and widespread bird species in North America.

Following the starling in abundance and in the scope of its range is the English sparrow, more commonly known in America as the house sparrow. House sparrows were introduced to Central Park in the 1850s to control an outbreak of green inchworms that were destroying the park’s trees. In an attempt to control one problem, another problem of a greater magnitude was created. Starlings and house sparrows have proliferated to the extreme and exerted irreparable damage to native and migratory birds in North America.

Habitat loss is generally considered to be one of the most pressing factors in the serious decline of many bird populations. Not far behind and becoming more of a problem all the time is the damaging effect of introduced species, especially the cavity-nesting starling and the house sparrow. Both of these species are aggressive and will often win out when competing for a nesting site with smaller birds. Starlings will even destroy eggs or fledglings in the process of taking over a suitable nesting site.

Programs are underway throughout the continent to provide nesting boxes that are designed to keep out starlings and house sparrows, yet provide for birds such as swallows and wrens. Larger species, such as woodpeckers and even some small owls can be intimidated by these avian thugs and are forced to find alternate sites or create new ones. Two local projects have begun to provide nesting boxes that are exclusively intended for violet-green swallows and purple martins.

Introducing nonnative or exotic species often has deleterious effects including extinction of native and migratory species, but the starlings and house sparrows also add to the problem with crop loss and even damage to buildings. Efforts are underway to find a solution to this growing problem but, so far, no consensus has been reached. Other places in the world, like Hawaii, New Zealand and Puerto Rico have seen introduced exotics become more common than native species.

For the benefit of future studies, there is a classic example—a virtual classroom—of the devastating effects of introduced species. The Hawaiian Islands are part of a 1,500 mile-long archipelago and their geographical isolation promoted the unique and remarkable evolution of its native species. Species became separated from one another within the archipelago and evolved independently to adapt to available food sources. As few as 15 original species are known to account for 70 kinds of birds that evolved before the arrival of humans.

Many of Hawaii’s indigenous species have been lost forever, due to the arrival of pigs, dogs, rats, and the introduction or escape of more than 150 species of exotic birds, including Java sparrows, shamas and common mynahs. There is no end in sight for the plight of endemic species in Hawaii, as they cling tenaciously to less and less of a foothold every year. However, efforts are underway in Hawaii to strengthen regulations that will eventually put a stop to the “biological pollution” of Hawaii’s unique native ecosystems.

The introduction of nonnative species presents an array of problems, such as competition and hybridization with native species, disease, crop damage and general nuisance. In North America, the migratory Bird Treaty Act of 1918 protects all wild birds except starlings, house sparrows and another introduced species, the rock pigeon—the common pigeon of cities worldwide. Introduced species pose a great dilemma for humans and a solution to the problems that are inherent with their growing numbers will not be easy. Preventative measures, as well as aggressive measures, are being studied to deal with the problem. If passive measures don’t work, the distasteful alternative could be the only answer—much to the dismay of many.

At this point, the “Wild Parrots of Telegraph Hill” pose no significant threat to native species. Perhaps this was also the hypothesis in the 1800s when starlings and house sparrows were introduced into Central Park. If nothing else, this is serious food for thought; especially when combined with the numerous and growing threats posed by global warming and a noticeable indifference on the part of the current administration. §