From starving chicks come fat birds

Dr Andrews, of the Newcastle University Centre for Behaviour and Evolution said: "Building up body fat reserves as a safeguard against times of potential future famine is an evolved survival mechanism. What we have shown is that birds that had struggled against larger brothers or sisters for food early on were keener on finding food and tended to overeat when they became adults".



To ensure that some birds were disadvantaged by experiencing greater competition, smaller starling chicks were placed in a brood with significantly larger hatchlings. These chicks had to work harder than their siblings to be fed, spending more energy on calling to their parents for food and jostling to the best feeding position.

Dr Andrews explains: "The smallest chicks were bottom of the heap and had a tougher time because they would have had to beg hardest for food."
These disadvantaged chicks were compared with birds that were placed in broods with significantly smaller chicks. After ten days, disadvantaged and advantaged chicks all lived together in relative luxury so that it was only their 'chickhoods' that differed.

Birds that had a tougher start spent more time searching for hidden crumbs despite the ready availability of alternative sources and ate more of the freely available crumb when they accessed it. The birds that had an easier start, having been the largest in the nest, opted instead to take the easy pickings in moderation.
The scientists suspect that the birds with a tougher start, the disadvantaged starlings, were behaving as if they were worried food might run out suggesting that they have a 'memory of hunger' from when they were small which drives them to overeat when presented with freely available food.