In the late 19th century, a group called the American Acclimatization Society released about a hundred starlings in New York City's Central Park as part of a project to introduce all the birds mentioned in Shakespeare's plays into America. Even knowing nothing about starlings, you may recognize this as an idea that is both baffling and terrible.
Of course, the birds just took over.
The released birds went on to reproduce like mad, increasing their numbers to somewhere around 200 million. By all accounts, starlings are natural terrors. They will force other birds out of their nests and eat their eggs. They swarm in those massive flocks, just eating absolutely everything they can fit in their beaks, stealing food from other species and wreaking havoc on agriculture.
And that's just the first of eight stories! Contains NSFW text. Link