While it's true that birds of a feather fly together, an open-minded pair of adoptive parents on a reserve in UK are proving that it needn't always be the case when raising a family.

Staff at the Slimbridge Wetland Centre in Gloucestershire were surprised to discover that two swans there had taken in a tiny baby goose under their wing, bringing it up as if he were one of their own.

"What is clear, is that the goose has imprinted on the swan and clearly thinks she is mum and vice versa," says reserve warden James Lees.

Still, no one knows for certain how the interspecies offspring made his way into the family, but Lees has his theories:

"It can be one of two options -- either the swan took over the nest of a goose and started to incubate the egg, or a greylag goose laid an egg in the swan's nest," he says. "I saw it on the nest incubating eggs over the last few weeks but this was the only youngster to emerge."

Regardless of how the swans became caregivers to the goose, they're certainly taking the job as seriously as they would if he was really their own. The doting parents have been seen protecting the small chick from outsiders, and also trying to shield him with their wings when it begins to rain.