It now needed to build up energy before it could migrate for the winter, said Mr Waterhouse.
Older ospreys typically postpone their winter migrations until their all young have migrated first.
Mr Waterhouse said the osprey’s other chicks had already migrated – most likely to west Africa.
“But our male osprey is staying on…to help this young osprey survive and build up the strength,” he said. “It’s really, really interesting behaviour.”
Mr Waterhouse is relatively certain the male osprey and the chick are not related because ospreys are generally “faithful to their site and female”.
“If this male osprey had another nest with a female on it…I think we would know.”
The team are expecting the young osprey to be healthy enough to migrate in the next two weeks.