SAN FRANCISCO (AP) — A lone coyote stunned biologists and others when it paddled its way to remote Alcatraz Island earlier this year, a former federal prison in the San Francisco Bay surrounded by swift, choppy waters notorious for thwarting prisoners’ escapes.

At the time, biologists guessed the coyote swam from San Francisco, which is a little over 1 mile (1.6 kilometers) from the fortress. But it turns out the male coyote actually made an even longer swim from nearby Angel Island, 2 miles (3.2 kilometers) away.

“Our working assumption was that the coyote made the swim from San Francisco because it is a significantly shorter distance. We couldn’t help being impressed by his accomplishment in making it to Alcatraz,” National Park Service wildlife ecologist Bill Merkle said in a Monday news release titled “Alcatraz Coyote Wasn’t a City Boy After All.”

“Coyotes are known to be resilient and adaptable, and he certainly demonstrated those qualities,” he said.

Camilla Fox, founder and executive director of nonprofit Project Coyote, said the coyote likely departed its home base in search of a mate or new territory to defend. She said coyotes, like wolves, do swim, although it’s incredibly rare for humans to spot one doing so.