Birds invent new songs in evolutionary fast-forward

May 02, 2011
North Island saddleback Credit: Martin Sanders

Native North Island saddlebacks have developed such distinctive new songs in the last 50 years that it is not clear if birds on one island recognise what their neighbors are singing about, a Massey University study shows.

The phenomenon is an avian equivalent of the way human develops regional accents and dialects as people migrate and settle in new locations, and provides fresh insights into how species evolve, says researcher Dr. Kevin Parker, from the Institute of Natural Sciences at Albany.

He made 2700 recordings of male saddlebacks’ rhythmical song on 13 islands off the coast of the North Island where the bird is found, for his doctoral thesis. When he compared them, he found only 30 per cent of the 202 different songs are shared between islands, with 70 per cent restricted to just a single island.

The study highlights the unexpected impact of human intervention – albeit well intentioned – on fundamental evolutionary processes. In this case, efforts to save the saddleback from extinction have led to dramatic changes in vocal diversity across islands probably due to “cultural bottlenecks” and “cultural mutations,” says Dr. Parker, who recently graduated with a PhD in Ecology. New Zealand’s conservation and translocation expertise combined with its protected offshore islands has created a unique opportunity to study and understand why the song of a bird species varies in different locations, he says.

In a series of experiments to test recognition of birdcalls, he played back recordings of familiar and unfamiliar saddleback songs to 10 pairs of saddlebacks on Motuihe Island, and observed their reactions. In cases where the mating or territorial song was more ‘foreign’, the either did not respond or left the area.

Thus, a love song for one saddleback might be nonsense to another, Dr. Parker says. “In humans, love overcomes language barriers, but in many bird species if you sing the wrong , you are out on your own.”

These variations in birdsong for mating and territory defence among isolated saddleback populations have emerged over the last 50 years, providing a snapshot of a ‘micro-evolutionary” event, says Dr. Parker. It is likely the changes have come about through loss of songs following conservation translocations and subsequent errors in learning or imitating songs within new populations, he says.

Endangered saddlebacks have been translocated from the original population on Hen Island to protected pest-free islands, initially by the New Zealand Wildlife Service in the 1960s and more recently by the Department of Conservation and community conservation groups. In that time, groups of between 20 and 50 birds have been moved to little-known Whatupuke, Lady Alice, Coppermine, Red Mercury, Cuvier, Stanley, Mokoia and Moutuhora Islands, as well as better-known Tiritiri Matangi, Little Barrier, Motuihe islands in the Hauraki Gulf, and to Kapiti Island off the coast of the Wellington, and mainland sites of Karori, near Wellington and Bushy Park, near Whanganui.

“It’s likely that the songs on different islands are similar to regional accents but in time they might progress to new languages – a bit like the development of Polynesian languages in the Pacific or the Romantic languages in Europe, a reflection of patterns of human colonisation,” Dr. Parker says.

In his current postdoctoral research, Dr. Parker is planning translocations of saddleback from three separate islands to two mainland sites, Tawharanui Regional Park and Maungatautari in the central North Island, where he will be able to observe what happens when saddlebacks with three different ‘dialects’ meet.

Explore further: Intrepid scientific explorer recounts lifetime of work and adventure in Amazon

Related Stories

Rare parakeets to populate gulf islands

Jan 29, 2008

An ambitious plan to translocate 100 kakariki (red-crowned parakeets) from Little Barrier Island to two other Hauraki Gulf islands as well as a mainland site means more people will be able to see the rare ...

New Zealand bird outwits alien predators

Jun 04, 2008

New research published in this week's PLoS ONE, led by Dr Melanie Massaro and Dr Jim Briskie at the University of Canterbury, which found that the New Zealand bellbird is capable of changing its nesting behaviour to protect ...

New wintering grounds for humpback whales using sound

Mar 08, 2011

Researchers at the Hawai‘i Institute of Marine Biology (HIMB), an organized research unit in the University of Hawai‘i at Mānoa’s School of Ocean and Earth Science and Technology have made ...

Recommended for you

Rare new species of plant: Stachys caroliniana

15 hours ago

The exclusive club of explorers who have discovered a rare new species of life isn't restricted to globetrotters traveling to remote locations like the Amazon rainforests, Madagascar or the woodlands of the ...

Mysterious glowworm found in Peruvian rainforest

18 hours ago

(Phys.org) —Wildlife photographer Jeff Cremer has discovered what appears to be a new type of bioluminescent larvae. He told members of the press recently that he was walking near a camp in the Peruvian ...

The unknown crocodiles

20 hours ago

Just a few years ago, crocodilians – crocodiles, alligators and their less-known relatives – were mostly thought of as slow, lazy, and outright stupid animals. You may have thought something like that ...

User comments : 0

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.