The adventurous coyote that has been living on Alcatraz since paddling more than a mile across the San Francisco Bay is growing “much fatter” thanks to the former prison island’s all-you-can-eat bird buffet.

The yet-to-be-named canine is “well and thriving” on the 22-acre island — and has been feasting on fowl, whose carcasses he is apparently littering across the state-run grounds.

“He not only survived, but he is well and thriving,” Janet Kessler, a “self-taught naturalist,” reported on her Instagram account that documents San Francisco’s urban coyote population.

A coyote swimming in the water. Aidan Moore

A picture showed the beast basking in the sun on a corner of the island, appearing noticeably thicker than the bony, shivering coyote that dragged itself onto the former prison’s rocky shores in a video that went viral earlier this month.

The new snapshot of the lonesome animal was apparently taken by a friend of Kessler on Jan. 24 and shows a massive turnaround within just two weeks of the animal’s daring 1.25-mile swim from the mainland.

The coyote’s health can mostly be attributed to a feast of fowl found in the many bird nests near the historic island’s parade grounds, where officials say the animal has mostly been living and leaving harvested carcasses in his wake.

Coyote walking on the rocky shoreline of Alcatraz Island. Aidan Moore

“He’s certainly much fatter than when he arrived,” Aidan Moore, who works for Alcatraz City Cruises, told The San Francisco Standard.

“We don’t know how long he’s going to be a resident here, because if he interferes with the nesting birds he might get relocated to the mainland.”

The coyote is the first and only to live at Alcatraz since the island was transferred to the National Parks Service in 1972.

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“Park biologists and staff are actively monitoring the coyote to better understand how it is surviving on the island and to assess any potential impacts to the seabird breeding colony,” a rep for the service said.

Activists like Kessler, however, are urging rangers to let the coyote enjoy its new life on the island after surviving the incredible feat.

“He expended a huge amount of effort to reach the island. If he can survive there, we should allow him to, allowed to live the life he has chosen. We all know that relocation is detrimental to coyotes and many don’t survive. This coyote poses absolutely no danger to people — he will stay away from them,” Kessler wrote.

“Lets stand back, watch, learn, and be awed by our wildlife and their amazing survival skills. We don’t need to always control and interfere.”