A lone coyote that swam more than a mile across the San Francisco Bay to Alcatraz Island is being monitored by scientists and could be moved if its presence threatens birds on the infamous Californian island.

The canine, called Floyd, appears to be thriving on The Rock - renowned for its abandoned prison - and getting by on an avian diet.

Whether Floyd can stay on Alcatraz depends entirely on how it behaves, says Aidan Moore, a local tour guide who shared footage of the coyote's journey.

Complicating matters, he adds, is that there are no fresh water sources, which could make the animal's welfare dependent on human intervention.

Video footage of Floyd - believed to be a male - hopping onto Alcatraz's rocks was captured by a tourist and shared with Moore. The gaunt coyote appeared to be shivering from the bay water which is about 10C (50F). But he has plumped up since, says Moore, who is originally from the Cotswolds, in England.

Park biologists and staff are actively monitoring the coyote to better understand how it is surviving on the 22-acre (89,030m) island and to assess any potential impacts to the seabird breeding colony.

This coyote is the first documented coyote presence on Alcatraz since the island was transferred to the National Park Service in 1972, the GGNRA said.

Kessler, a naturalist, suspects Floyd made the journey due to interspecies territorial pressure in the city. Project Coyote, which focuses on the coexistence of wildlife in urban areas, is also concerned about the safety of both the coyotes and tourists on the island.

As scientists continue to track Floyd, the hope is that he can not only survive but thrive, making Alcatraz his new home—or perhaps return to the mainland when the time is right.