DNA analysis by the University of California, Davis found the animal came from Angel Island, making the San Francisco Bay crossing 2 miles rather than the previously assumed 1 mile from San Francisco.
National Park Service biologists said video showed the swim in early January, and a visitor later photographed the coyote on 24 January after it reached the former prison island.
Officials had considered capturing and relocating it because Alcatraz is a seabird nesting habitat, but it has not been seen again and there is no evidence it remains there.
With the coyote's fate unknown, could Alcatraz see more wild visitors in the future, and what would that mean for its delicate seabird colonies?
How did a lone coyote overcome the frigid, swift currents to reach Alcatraz—when even most human escape attempts famously failed?
What might the coyote's unprecedented swim tell us about animal adaptability in human-altered landscapes—and how should we rethink coexistence strategies?