Workers at Scotland's Perthshire nature reserve are surprised after Lady, thought to be the country's oldest osprey, laid a fourth egg for the breeding season.
The 27-year-old osprey - also known as a sea hawk or fish eagle - is a fish-eating bird of prey. For an osprey to lay a clutch of four eggs is rare, the BBC reports, and the raptor's age makes the occurrence all the more remarkable. Usually an osprey will lay two or three eggs, although Lady did lay four eggs in 2005.
"This is not the first time this female has done this - she laid four eggs in 2005, and of course in the years before close up nest cams, when we had to wait until we could see the chicks heads above the nest rim, there may have been other incidents of this," said Scottish Wildlife Trust Ranger Emma Rawling, who monitored the osprey nest from a webcam.
"However, it is considered rare in ospreys, and is a remarkable achievement."
Roy Dennis, an osprey expert, said the bird must have been in "exceptionally good condition" to have laid a fourth egg. One study conducted by Dennis found that of nearly 500 osprey clutches, only one percent had four eggs, the BBC reported.
But the future may be grim for the bird in the fourth egg. The bird in the fourth egg from 2005 survived only a few hours after hatching.
Rawiling said that she is only aware of one instance in Scotland where a clutch of four were all successfully raised to fledgling.