Eugene Schieffelin thought he was doing his fellow New Yorkers a favour when he released 60 European starlings in Central Park on March 16, 1890. Schieffelin, a German immigrant whose family had distinguished itself in the field of pharmacology, was a member of the American Acclimatization Society which sought, according to its charter, to introduce "such foreign varieties of the animal and vegetable kingdom as may be useful or interesting."

He was, it is said, a little eccentric; the inspiration behind his acquisition of the starling specimens was to provide Americans with physical examples of every bird mentioned in the plays of William Shakespeare. The starling (Sturnus vulgaris), by all accounts, even its name, a vulgar, scheming bird, is mentioned only once in all the bard's scribings. In Henry IV, Part I, when Young Henry Percy, known as Hotspur, wants King Henry to ransom Edmund Mortimer, the Earl of March, held by outlaws in Wales, he determines that he will be able to sway the king by repeating the name Mortimer. He decides the best way is to teach a starling to mimic the sound of his name: "I'll have a starling shall be taught to speak nothing but 'Mortimer', and give it him, to keep his anger still in motion."

Today the descendants of the imports brought to America on a whim, number 200 million. They have driven many indigenous species such as the bluebird and the flicker from their traditional nesting grounds, many say in a planned, deliberate fashion. Their droppings, produced prolifically where they roost, are also cause for consternation. On one occasion 11 tons of starling poo had to be scraped off the dome of the state capitol in Springfield, Illinois. As Stan Richards and David Culp put it in their book The Peaceable Kingdom, which uses the lesson of the starling as a parallel for introducing radical initiatives in business without first determining the repercussions: "Shakespeare would have been flattered (til he had to wash the poop off his car)."

Photograph: Starlings over Tøndermarsken, south-west Jutland, Denmark, (