June 11, 2008

Family Tree Shows Vulnerability In Some Bird Species

A scientist has created a new family tree of birds in the UK in hopes of successfully being able to forecast which birds have a higher likelihood of declining in the future.

Compiled by Gavin Thomas, the list of 249 species shows that populations of birds that are more closely related have higher chances of surviving. Therefore, he indicates in the Royal Society's journal Proceedings B, even healthy species of birds may be at risk if its relatives begin to disappear.

For example, decline in the song thrush, mistle thrush and starling could forecast problems for the now thriving blackbird.

Likewise, falling numbers of linnets and bullfinch might suggest that the greenfinch is not as safe as its numbers would imply.

"This hasn't been tested on the ground, so we don't know at the moment whether the inferences we're making turn out to be true," Dr Thomas said.

"And it could be some years before we do know - but I think it could be a kind of early warning system."

The population biologist from Imperial College London found that genetic sequences from almost all of the UK's birds had already been analyzed and made public.

"As far as I can tell, this is the first time that anyone has attempted a complete phylogeny, and I was quite surprised - you'd think that they'd be one of the first groups of animals to be done because of all the interest there is in them, at least in Britain," he added.

Rob Robinson, senior population biologist at the British Trust for Ornithology, called Thomas' tree "a fantastic piece of work."

"It's going to be incredibly helpful in terms of doing some of our analyses," he said, but cautioned that he was unsure whether it offered definitive evidence as to whether or not a species was more likely to decline.

"The buntings, which are all declining, all live on farmland so you would think that anything that affects farmland would affect them all," Robinson said.

"But I'm not convinced that the decline in thrushes implies trouble for blackbirds, which appear more adaptable in terms of food supply."

The BTO is set to begin a study of blackbirds in the UK in hopes of providing a clear picture of the status of these versatile feeders.

Numbers have been steady over the last 35 years, whereas starlings have declined by 70%, mistle thrushes by 40% and song thrushes by 50% (though numbers of the last may be recovering now).

Gavin Thomas agrees that this kind of research - on the ground, examining the habitats, the food and the behavior - is top of the tree when it comes to forecasting prospects for birds.

Still, he insists that there are cases in some countries which the genetic tree would not show conservation agencies when to begin remedial measures - but it might show them which species they should be keeping a closer eye on.


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Proceedings B


Imperial College London