Understanding bird song could help preserve endangered species: study

WELLINGTON, May 23 (Xinhua) -- Breeds of birds that have been moved to save them from extinction are developing songs that are unique and different to their original source populations, New Zealand scientists have found.

Ecologists from the University of Waikato and Lincoln University studied the North Island kokako, an iconic bird with a organ-like song, which was once widespread in the North Island.

However, habitat loss and predators, such as rats, possums and stoats, had destroyed populations so much that fewer than 400 pairs survived by 1999.

Between 2001 and 2007, several pairs were moved from the central North Island's Te Urewera National Park to two other reserves.

The researchers made hundreds of recordings in the three populations and analyzed differences in bird song using sonograms, before playing the recordings to other populations to see how they reacted.

They found the songs of translocated birds had diverged substantially from the source population, becoming less diverse with shorter and higher-pitched elements.

"Not only how kokako sing in translocated populations, but also what they sing differs from kokako in the source population," Lincoln University researcher Dr Laura Molles said in a statement on Thursday.

The greatest changes were found in the population that had been translocated the longest time, indicating the songs could become more different over time.

"As translocation usually involves only a small number of individuals, they will take with them only a small portion of all the song elements in the larger source population. Subsequent variation in small populations will depend on that subset of songs and will then differ from the larger song pool in the source population," Molles said.

The study had important implications for conservation as song incompatibility between populations would occur over time, which would hinder interbreeding as new birds were introduced.

"We need to be aware that behavioral factors like song can also affect translocation success and recovery of endangered birds, and adapt our management of these populations accordingly," said Molles.

The North Island kokako is about the size of a common pigeon, with blue-grey plumage and a black mask and striking bright blue wattles.

Both sexes sing and pairs duet, with organ-like notes that can be heard over 1 kilometer away.