The actions of a domestic cat have thrown up a new theory about ancient stone burial cairns in Caithness.
A cat has changed thinking about ceremonial offerings
Archaeologists built a mock-up of the structures as part of an experiment.
Emma Sanderson, of Caithness Archaeology Trust, said it was found that a dead rabbit had been left in the replica by a cat.
She said it could mean that animal bones found in real cairns were not the remains of ceremonial offerings, as thought, but left by other creatures.
Archaeologists built reconstructions of burial cairns and ancient towers called brochs as part of a series of research projects and excavations carried out in Caithness over the summer.
Prince Charles, who is on holiday at Castle of Mey, visited the ruins of a broch near Keiss this week.
A team from Nottingham University also dived to a number of wrecks off the Caithness coast, including one thought to be a World War I German warship.
The archaeologists are now analysing their field work, including new insights into cairns.
"One day a couple of weeks ago a dead rabbit was laid out in the cairn. It had been placed there by a cat," said Ms Sanderson.
She said it was previously thought that animal remains found in actual cairns were left as ceremonial offerings.
However, the cat's dead rabbit has provided a new theory that they had been killed by other animals years after the cairn had fallen into disrepair.
Another theory about cairns may also have been exploded after archaeologists knocked down their mock-up.
It was noted that the stones collapsed in a pattern previously thought to be evidence of ceremonial closing of the cairn.