Birds sing different tunes throughout country

The saddlebacks of Whale Island off Whakatane sing a different song to the saddlebacks on the Hen and Chicken Islands off Whangarei.

And groups of tui, bellbirds and grey warblers also have their own regional language and song.

This remarkable discovery by biologists about New Zealand's native birds has emerged from research on islands where wildlife thrives in the absence of predators.

Massey University researchers led by Associate Professor Dianne Brunton have found the birds are forming distinct songs and calls unique to the area they live in - not dissimilar to human dialects.

Dr Brunton's PhD student, Kevin Parker, recently returned from collecting calls on Whale Island near Whakatane, one of 10 islands where researchers have tracked groups of relocated saddleback.

Saddleback were chosen because the early island populations all came from the same area. Some of these islands also have historic recordings - some dating back 30 years.

"Because we know the history of all these translocations and they came from a single source, we know we can plot the changing dialects over time."

Dr Brunton said saddlebacks on the Hen and Chicken Islands - among the first islands where populations were set up - have a more varied call, while younger populations, like those on Whale Island, have less variety.

Dr Brunton said it was more complicated than just saying each group had its own way of speaking, as each island has its own cluster of dialects.

The original song appeared to evolve over time. Changes could be readily heard even in a two-year period, she said.

"They make mistakes - and those get incorporated - they repeat some parts, they drop some other parts out and they may use some of the other calls, such as the chatter calls, and incorporate that to their territorial song."

The project, made possible through a Marsden Fund grant, looks at the cultural evolution of birds, but Dr Brunton said it had practical applications in conservation, especially since much of New Zealand's bird preservation work was done through relocating seed populations to predator-free islands.

"Song is an important part of mate choice, territory ownership and associated behaviours. If the translocations are altering that, they are altering the fundamental part of bird behaviour."

The project, in its second year, has already provided some definite conclusions. Other projects taking place simultaneously were looking at similar dialect patterns in bellbirds, warblers and tui, said Dr Brunton.

"Tui are a really interesting species to work on. They incorporate, copy and mimic, and we find all sorts of differences between individuals in island populations."