When a typical day at work involves balancing on a small platform that's dangling off a building hundreds of feet in the air, you'd think a visit from a bird would be the least of your worries. But you'd be wrong. While suspended on a building in Milwaukee a pair of workers were forced to take cover when a falcon launched an aerial attack, swooping in repeatedly to divebomb the cowering duo.

Friendly warning: the video contains strong language (which is forgivable given that the workers had a falcon flying at speed towards their heads).

"This is not a safe work environment!" one of the workers who filmed the action can be heard shouting through a swell of nervous laughter. You can say that again. It's unclear how the ordeal ended, but we're hopeful neither human nor bird was injured.

The angry attacker that was "trying to kill" the workers is a peregrine falcon and it was probably just defending its nest. These speedy raptors – the fastest flying animals in the world – are known to make use of skyscrapers as urban equivalents to the rocky cliffs that they use when nesting in wilder spaces. The predatory birds are believed to mate for life and may use the same nest site for several years– a nest site which they will defend aggressively against any potential intruders.

The workers in the viral video appear to be dangling off the face of Wisconsin's tallest building, the U.S. Bank Center, which has a storied history with the state's peregrine falcons. In the 1960s, falcon populations across much of the United States had all but vanished largely as a result of the widespread use of pesticides like DDT. Wisconsin banned the use of the harmful chemical in 1972, with the federal government following suit a year later, but the damage was already done and many bird species suffered dramatic declines. 

In Wisconsin, keen conservationist and falconer Greg Septon launched an ambitious recovery project. He got to work acquiring a small population of captive-reared peregrines to kickstart their reintroduction in the state. Milwaukee's famed skyscraper was the temporary home of 14 falcons that were housed in artificial nest boxes on top of the building back in 1987. Over the next five years 103 falcons were released in Wisconsin forming a population robust enough to start breeding on their own.

The birds have adapted incredibly well to an urban lifestyle and appear content to nest in artificial 'scrapes' created in the shadow of power plants or atop tall buildings. Since the early 1990s, over 400 peregrine falcons have hatched at nest boxes erected at We Energies and Wisconsin Public Service (WPS) facilities making up a pretty hefty percentage of new birds born in the state.

So the sight of a peregrine falcon in Milwaukee is actually a positive sign of dedicated conservation in action (even if the bird is swooping full-speed at your head). 

Header image: Mosharaf hossain