The residents of an island in Northland are grappling with an unusual problem - they have too many kiwi.

Seven kiwi captured near Waitangi, when their bush habitat was about to be cleared for pine forest, were released onto Moturoa island in the 1980s.

Since then, kiwi numbers on the island, near Kerikeri Inlet in the Bay of Islands, have grown into the hundreds - and that has put pressure on the limited habitat and food available for the protected birds.

As a result, 21 kiwi caught on the island were released in Opua State Forest on Friday, easing the island’s population boom and boosting kiwi numbers on the mainland at the same time.

The operation would not have been possible even a few years ago but a massive pest control effort in Opua forest, which cloaks the hills behind Paihia, has made the area safe for the flightless birds.