The Humboldt penguin, one of 135 kept at Tokyo Sea Life Park, was recaptured after 82 days of freedom that had even seen it outwit Japan's well-resourced coastguard.

The bird’s last moments of liberty were lived on a riverbank just eight kilometres (five miles) from its home, said aquarium spokesman Takashi Sugino.

Prompted by a stream of sighting reports, staff rushed to the Edo-gawa river, where the young bird was idling away a balmy Thursday afternoon, seemingly unaware that its adventure was coming to an end.

As its captors approached, the creature dived into the water and emerged onto the opposite river bank about an hour later.

Undeterred, aquarium staff tried again, this time approaching the startled bird slowly — taking some 20 minutes to close in the final five meters (16 feet) — before jumping on it.

The one-year-old bird, known only as Penguin No. 337 and not yet old enough to display physical sexual features, rushed into the water in surprise, but was subdued and taken back into custody.

“It was captured safely,” the aquarium said in a statement.

“It does not appear to have any injury and it seems to be in good health.” The penguin is now undergoing through medical checks and will be quarantined for possible infections before rejoining the rest of the flock, Sugino said.

More than 30 sightings of the 60-centimetre (two-foot) penguin had been reported to Tokyo Sea Life Park since it fled.

The bird had been spotted swimming in various locations around Tokyo Bay but was difficult to catch.

Even Japan’s coastguard were caught flat-footed by the escapee.

On May 7, two boats with 10 officers on board followed the bird for about an hour before it disappeared from view.

The hunt for the bird, which the aquarium said did not have a name, began in early March after it was spotted bathing in a river that runs into Tokyo Bay.

Keepers believe the creature made its break for freedom after being startled into climbing over a rock twice its size.

In a bid to curtail any future breakouts, the facility has now put additional rocks and sandbags around the edges of the penguin enclosure.