Britain's oldest-known golden eagle has been found dead after an apparent territorial dispute with a younger rival.

The bird was ringed at just a few weeks old in June 1997 and its carcass was discovered close to a nest site in Sutherland almost exactly 18 years later.

RSPB Scotland said tests confirmed it had died from natural causes.

A spokesman said: "We think what might have happened is that a younger bird has come along and there has been a bit of a tussle because the older one doesn't want to give up its territory, and these fights can result in death.

"Although conjecture, we think that is the most likely explanation."

The eagle, who was not named, was found dead near its nest in Forsinard Flows.

It is not known if the eagle was male or female.