On a wing and a song, bellbirds gatecrash own surprise party

A small songbird mostly restricted to living offshore anywhere near Auckland has moved into a new mainland home before getting the official invitation.

Around 100 bellbirds have been discovered in Tawharanui Regional Park near Warkworth over the past three weeks, making plans to re-introduce the birds redundant.

"They've saved us a lot of trouble and staff time by turning up all on their own," said Auckland Regional Council chairman Mike Lee.

The birds are thought to have flown over from nearby Little Barrier Island, about 20km off the coast of Tawharanui, because their "dialect" was similar to the island's birds, according to ARC scientist Tim Lovegrove.

While the occasional bellbird has been seen at the park over the past few years, the ARC is hoping this population is permanent.

"What's been surprising is the number of birds and the fact some are very young, indicating they have set up a breeding population," said ARC director of heritage Graeme Murdoch.

Work to transform Tawharanui into an open wildlife sanctuary began in earnest five years ago. A group of locals raised $400,000 of the more than $600,000 needed to erect a 2.5km predator-proof fence which will eventually house other rare species of birds and reptiles.

Project manager Jo Ritchie said pest eradication was in its final stages and it was a healthy sign the bellbirds had moved in early.

"It's pretty exciting," she said. "I think we underestimate the power of nature to restore itself."