In 1948, the residents of McCall, Idaho, were complaining about beavers. The beavers had always been there, it was the people that were new, and they didn't want to share their lakeside paradise. The Idaho Fish and Game Department decided the beavers should be moved, but since most of Idaho was still wilderness at the time, trucking the animals out would be difficult and dangerous. However, in that postwar era, the US government had plenty of surplus parachutes, so why not drop the beavers into their new homes from the air? That's just what they did.
It wasn't as easy as it looks. The location, altitude, and weights of the beavers had to be calculated just so. The biggest challenge was designing a way to protect the beavers during their descent and releasing them once they landed. Read how that was accomplished at IFLScience.