Among the 1,000 established species of birds in the U.S. about 97 were introduced. Of those, only 5 percent are considered beneficial--chickens, for example--while most are pests. Peskiest of all is the ubiquitous pigeon, which racks up an estimated 1.1 billion a year in economic costs. Add in a few other interlopers, such as the starling, and the total comes to $2.1 billion.

Sparrow
Image: FRED MULLEN

ENGLISH OR HOUSE SPARROW (Passer domesticus) (see image left) was imported to the U.S. in 1853 to control the canker worm. Like other non-indigenous species they didn't limit themselves to canker worms. They damage decorative plants and devour wheat, corn, and buds of fruit trees; they harass robins, Baltimore orioles, yellow-billed cuckoos, and black-billed cuckoos; they displace bluebirds, wrens, purple martins, and cliff swallows from their nest sites; and they spread about 29 diseases of humans and domestic animals. The researchers peg their cost at $200 million a year.

DOMESTIC PIGEONS (Columba livia) spend their time feeding on grain and fouling buildings, statues, cars, and sometimes people in most cities of the world. One study estimated the economic impacts of fouling at $9 per pigeon per year. Assuming there are 0.5 pigeons per person in the urban areas, the Cornell group estimates that common pigeons cause at least $1.1 billion in damage each year. They are also reservoirs for over 50 diseases, including parrot fever, ornithosis, histoplasmosis and encephalitis.

Starling
Image: NBII

EUROPEAN STARLINGS (Sturnus vulgaris) (see image right) form huge flocks that wreak havoc in agricultural areas. They can destroy about $800 worth of cherries per acre or gobble down about $2.50 per acre of grain. Assuming damage at $2 per acre on agricultural land, their toll is $800 million a year. They also have displaced numerous native birds and been implicated in the transmission of 25 diseases including parrot fever.
Data: Excerpted from Environmental and Economic Costs Associated with Non-indigenous Species in the United States

Back to Costly Interlopers