Macdonald thinks that the whales and dolphins are likely to be following their favorite snack.
"Sand eels prefer colder waters, and a huge amount must have come into the [Moray] Firth [an inlet of the North Sea in northern Scotland] this year," he said.
The warmer waters on the west coast may have become too hot, attracting the sand eels to the relatively cooler waters on the east coast.
However, warming oceans are not the only explanation for the whale invasion.
"Possibly we are getting more sightings because more people are looking now," Hoyt, of the Whale and Dolphin Conservation Society, said.
Whale- and dolphin-watching is becoming a popular hobby in the U.K., he notes, and the Scottish Seabird Centre in North Berwick has reported a huge rise in interest in whale-watching in recent years.
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