Quaker Parrot, Barcelona, Spain, June 10, 2011

According to news accounts, the growing population of Quaker parrots (presumably descended from abandoned pet birds) is causing alarm in Barcelona. Also known as the South American Monk parakeet, the Quaker parrot is said to be an aggressive bird that "eats just about everything green it can find - flowers, grass, even tree branches." And that, with a high rate of reproduction, the Quaker is threatening the survival of local bird species.

Other accounts (including one detailing a colony in Brooklyn, New York) are considerably less alarmist, contending that populations stabilize at a relatively low density. We will continue to follow this story. (Dave Sagarin, June 10, 2011)