The female osprey has a much younger male mate
The UK's oldest known breeding female osprey has surprised wildlife experts by producing her 56th egg.
Staff at the Loch of the Lowes reserve in Perthshire had doubted the 25-year-old bird's fertility.
However wildlife watchers spotted the Osprey, which recently returned from a 3,000-mile migration from west Africa, hunched over the egg via a webcam.
Ospreys live an average of eight years and are estimated to produce about 20 eggs during that time.
Emma Rawling, SWT's Perthshire ranger, said: "This individual bird is truly a wonder of nature."
She added: "The osprey faced persecution in the early 20th century and was very nearly driven to extinction by 1916.
"But our old girl seems determined to do her bit to help repopulate the species.
"This is the 56th egg she has produced, and so far 46 chicks have successfully fledged the nest over previous breeding seasons."
Since the bird's return from west Africa, staff have been watching her "train up" a new male mate.
Identified thanks to a green band marked '7Y' around his ankle, the 10-year-old male was initially a bit confused about his role in the breeding process, said Ms Rawling.
She said: "We have watched our female show him the ropes, calling out repeatedly in displeasure to entice her young mate to work harder to please her."
To complete his duties in breeding, a male osprey must provide food for the female as she sits on the nest, bring sticks to maintain the nest's condition, and protect the nest from other males, known as interlopers.
Throughout the breeding season the eyrie will be visible via a nest camera on screens in the visitor centre and on the trust's website.
A team of about 70 volunteers watch the nest 24 hours a day to safeguard any eggs from thieves and poachers.
About 200 pairs of osprey breed in Scotland.