The birds normally mate for life, but occasionally bond with another after one of the couple dies.

But for only the second time in more than 40 years of observations at the Wildfowl and Wetlands Trust center at Slimbridge, two previously paired birds have appeared with new partners.

“Failure to breed could be a possible reason, as they had been together for a couple of years but had never brought back a cygnet,” wildlife officer Julia Newth told the BBC.

She said the old pair had not acknowledged each other with any signs of recognition or greeting, even though they are occupying the same part of a small lake.

Bewick’s are the smallest and most rare of the three swans found in Britain.

It was discovered in 1965 that each individual of the species, which migrate to and from Arctic Russia, can be identified by its unique bill pattern.

Photo: Stock