Scientists at the University of Oxford have constructed a computerised egg to help crack open the secrets of how cygnets hatch at Abbotsbury Swannery in Dorset
Normally a swan lays 4-10 eggs, at two-day intervals, and during this time she will sit on the nest for most of the day to guard her eggs. Only when the last egg has been laid will incubation begin.This process means that cygnets hatch together and can therefore be better cared for. The mystery is: what happens to the temperature of the eggs?
Professor Chris Perrins, of the Edward Grey Institute of Field Ornithology at the University of Oxford, said: ‘It's something that's puzzled us for a long time. Birds don't normally waste energy and yet some preliminary observations during the laying period indicate that a female swan does keep her eggs at least partly warm some of the time.
‘But since the eggs hatch together, they are not apparently kept warm enough for development to take place. So why use up energy doing it at all? It seems odd. We want to understand in greater detail the amount of heat that a female puts into her eggs during laying and incubation and why and how it's done.'
To find out, Dr Stephen Ellwood of the Wildlife Conservation Research Unit (WildCRU) at the University of Oxford, used a diamond saw to cut off the top of a dud swan's egg. He cleaned out the addled contents, partly filled the shell with silicon and then fitted a miniaturised computer inside.
The computer has mobile-phone style accelerometers to measure movements up and down, left and right, and backwards and forwards. It can record these movements and changes in temperature eight times a second or more and then transmit these data to a nearby base-station.
Professor David Macdonald, Director of the WildCRU, added: ‘Our mission is to use science to help discover how to conserve species - since the early days of radio-tracking, cutting edge technology has revolutionised our understanding of animal behaviour, and contributed major insights to conservation - we expect this new technology to be as useful to conservation as it is interesting to science.'
Placed into a swan's nest at Abbotsbury alongside a clutch of normal eggs, scientists and Swannery staff now hope the computerised egg has transmitted enough information to reveal what goes on beneath a swan during nearly two months of laying and sitting and incubation. Computerised leg tags were also fitted to the parent swans using this same nest, as well as to two other pairs, and one individual.
Dr Ellwood said: ‘These kinds of devices make observations that were impossible, possible. People just can't go into the places that these devices can go.'
The Abbotsbury work is part of a one-year project being funded by the Knowledge Transfer Secondment scheme of the Engineering and Physical Sciences Research Council via Oxford University.