Birds with smaller brains less likely to survive

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Subject: Birds with smaller brains less likely to survive
From: knightl <>
Date: Wed, 14 Sep 2005 18:52:58 +1000,,1569265,00.html

Birds with smaller brains less likely to survive

Alok Jha, science correspondent
Wednesday September 14, 2005
The Guardian

Being bird-brained is far worse than the jokes might have suggested. Never mind that birds have never been one of the most intelligent animals, research shows that the smaller a bird's brain, the more likely the species is to die out in the wild.

British farmland bird populations have been declining for 50 years and the accepted explanation is the intensification of agriculture. Based on the fact that some species have survived better than others, researchers looked for specific characteristics that influenced survival rates.

Using data gathered by the British Trust for Ornithology between 1968 and 1995, they found that, as well as habitat loss through increased agriculture, there were basic biological reasons influencing survival. "There does seem to be a positive advantage to these birds in being smart," said Tim Blackburn, an ecologist at the University of Birmingham. "The size of the brain influences the probability that these farmland birds are declining."

The population of great tits, for example, increased on farmland by around 75%, and the number of magpies went up by 80%. However, the grey partridge population fell by 75% and the lapwing by 40%. The relative sizes of the brains in the former are bigger than those in the latter.

The brain has a variety of functions, but there are parts that scientists think are the sites of higher-level function. In mammals, the higher functions are concentrated in the cortex and the frontal lobe. In birds, the equivalent is an area of the brain called the telencephalon.

"When you release a bird in an environment it is not naturally distributed in, you'd expect that anything that could be more behaviourally flexible might be able to take advantage of their environment," said Dr Blackburn. "We think a similar thing may be going on here: these brighter species have more opportunity to be flexible and adapt to changing situations."

The results are published today in the Proceedings of the Royal Society B: Biological Sciences. "I just really didn't think that we would find these kinds of relationships," said Dr Blackburn. "It's not only that it was a brain size effect, it's when you break the brain down into these bits. The fact that it was the telencephalon that clearly came out in our models, I was amazed."

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