'Cyber egg' used to record Abbotsbury Swannery swans
Scientists have placed a computerised egg among a group of swans in Dorset.
The silicon-filled "cyber egg" will use mobile phone-style technology to measure movements of the birds at Abbotsbury Swannery.
Experts hope they can learn more about the behaviour of the swans during the hatching of their cygnets.
Prof Chris Perrins, of the Edward Grey Institute of Field Ornithology at the University of Oxford, said: "It's puzzled us for a long time."
A swan lays four to 10 eggs at two-day intervals, but cygnets hatch together.
Prof Perrins added: "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."
The "cyber egg" was made by Dr Stephen Ellwood, of the university's wildlife conservation research unit, by cutting off the top of a dud swan's egg with a diamond saw.
He then cleaned it out and placed a miniaturised computer inside.
He 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 temperature of the egg is recorded eight times a second and transmitted to a nearby base station.
Swanherd Dave Wheeler said Abbotsbury was the only place the study could be done without disturbing the birds.
He added: "Here they are used to our management and we can be intimately close at very sensitive times, throughout nesting and throughout hatching, and they're very used to that.
"If we didn't take advantage of this unique situation where the birds are so tolerant, I think it would be a crime."
The site has been home to the colony of mute swans for nearly 1,000 years.
They were originally used for food at the local Benedictine monks' lavish banquets.