The common Scoter duck which rarely breeds in the UK has had a successful season in its Highland stronghold, according to RSPB Scotland.
There are only thought to be 52 breeding common scoter females, half of them in the Flow Country which covers parts of Caithness and Sutherland.
At least 21 ducklings on the RSPB's Forsinard Flows Reserve have neared adult size.
The charity said this meant the birds had a good chance of survival.
RSPB scientist Dr Mark Hancock has been carrying out research on scoters in the Flow Country.
He said: "This huge and wonderful blanket bog, with all its lochs and wetlands, is precious for a wide range of wildlife, but especially crucial for the scoters.
"After recent declines in British scoter numbers, it was really exciting to find that such a large number of scoters had bred successfully in the Flows this year.
"As a bonus, the good breeding season has allowed us to study the behaviour of the young ducklings in much greater detail."
Source: BBC News