A Bewick's swan cygnet has been left "home alone" after his parents appear to have migrated to Arctic Russia, conservationists said.
The youngster seems to have been abandoned at the Wildfowl and Wetlands Trust (WWT) Slimbridge Wetland Centre in Gloucestershire.
Bewick's swans overwinter in the UK and Europe before returning to the Russian Arctic in spring, migrating north in large family groups, and due to the recent mild weather all but 10 of the flock at Slimbridge have already departed.
WWT researcher Julia Newth, who has learnt to recognise the hundreds of swans in the flock by their individual facial markings, noticed that one remaining family had acquired an additional cygnet.
The abandoned youngster has attached itself to swans Wooton and Stinchcombe and their four cygnets, but is still calling for its parents.
Ms Newth said: "Occasionally, cygnets become separated from their parents during migration when there is perhaps bad weather, but it is rather more unusual to see such a separation before the journey has begun.
"Visitors to Slimbridge are really taking the cygnet to their hearts and we're all waiting to see whether the parents return.
"If they don't, and it leaves with its adopted family, we will call on our extensive network of swan researchers along the 2,500 mile journey to Russia to keep an eye out for them and check whether the lone cygnet manages to stay with them."
Wooton and Stinchcombe are ringed and could be spotted with their family along the 2,500 migration route, where they will rely on a chain of wetland sites to rest and feed.