The sighting of sperm whales off Scotland's north-west coast in winter has been described as "extraordinary" by research charity Sea Watch.
Creel fishermen working between Loch Torridon and South Rona spotted the deep-diving whales on Monday.
Sea Watch said groups of sperm whales had been seen off Scotland in the summer, but it was unusual for them to be spotted at this time of year.
It said the change could be a sign of warming sea temperatures.
The animals spotted on Monday were initially thought to be humpback whales.
However, they were identified as sperm whales by Nick Davies, who runs Gairloch-based Hebridean Whale Cruises and is involved in a Sea Watch project.
Sea Watch director Dr Peter Evans confirmed the sighting from Mr Davies' photographs.
Dr Evans said: "In past decades, most records of sperm whales in British waters have been of lone adult males around Scotland, mainly off the Northern Isles and the Hebrides.
"Increasingly, however, adolescent males have occurred in our waters, sometimes in groups of five to 10 individuals."
He said the latest sighting was notable not just because it was made in winter, but also because of how close the whales were to shore.
Dr Evans added: "The increased occurrence of winter sightings in Scottish waters could be a reflection of climate change, with their main prey, squid, becoming more abundant locally in recent years, resulting in animals staying through the winter to feed rather than travelling into lower warmer latitudes."