There are more than 150 million European starlings in North America. We have two men to blame for this: Eugene Schieffelin, and maybe William Shakespeare.
The American Acclimatization Society was a late 19th century group of amateur naturalists who wanted to introduce European plants and animals to the “new world.” In the name of this ecological colonialism, they released hundreds of starlings into Central Park in New York in 1890 and 1891, in the hopes of seeding a new bird population.
They were absurdly successful. Starlings have since spread as far north as Canada, as far south as Mexico, and all the way to the west coast of North America. They’re a major ecological pest, displacing other birds and damaging crops.
The president of the Society was a pharmacist named Eugene Schieffelin. Some accounts hold that he was a big Shakespeare fan, and introduced the starling because it was mentioned in Henry IV, Part I:
I’ll have a starling shall be taught to speak nothing but ‘Mortimer’
Those accounts hold that he was trying to introduce all of the birds ever mentioned in Shakespeare. Shakespeare mentions 56 birds in his plays, although one of them is the phoenix and I think Schieffelin would have found that one difficult. Evidence for these accounts is spotty at best, but even if it’s true it is a terrible reason to pollute a continent.