Pen-chan, a female Cape penguin born and raised in captivity, who had never swum in the open sea before or fended for herself, absconded from an event in the central Aichi region on 25 August.
Her keeper, Ryosuke Imai, said a team began scouring the area immediately but a powerful typhoon that brought record rains across Japan hampered the search.
Given Pen-chan’s lack of preparation for life in the wild, the team thought she would not get very far or survive for longer than a week.
But on 8 September, Imai received information that the bird had been spotted happily bobbing in the water at a beach 30 miles (45km) away.
“I thought she would look exhausted, but she was swimming as usual,” Imai said after the animal was recaptured. “It was beyond my surprise … It’s a miracle.”
Mugshot of the perpetrator has been released: