Dozens of bottlenose dolphins from the Moray Firth population have made their way south and are now regularly seen off the coast of North Yorkshire.
Robin Petch, an experienced dolphin spotter who is an ambassador for Sea Watch Foundation, said they rarely ventured south of Aberdeen until the early 2000s but are now spotted in Yorkshire two or three times a week.
“There are two very distinctive groups. One is led by Guinness and the other is led by another extremely distinctive dolphin called Runny Paint,” he said.
“There are other groups of dolphins too, so there are probably at least 30 or 40 from the Scottish population who now spend more time in Yorkshire and North East England than they do in Scotland.
“Some of those dolphins have not been back to Scotland for three or four years.”
He added: “There’s a number of places you can look out for them and any sort of headland is always a good place, like Filey Brigg, Flamborough Head.”
Sea Watch Foundation said the white-beaked dolphin has become scarcer in Yorkshire in recent years, as climate change is believed to have affected the fish they prey on.
Harbour porpoise and minke whale populations have remained relatively stable, but the number of bottlenose dolphins in the county has increased significantly and it recorded 16 confirmed sightings last month.
While it is not clear why these majestic creatures, which weight around 500kg and live for around 50 years, have extended their range and decided to head south there are a number of theories.
Mr Petch, who has been monitoring dolphin populations since the 1990s, said they may have migrated because their food supply has been impacted by industrial fishing in Scotland and there has been a marked increase in ship traffic around Cromarty Firth.
But he also said fish populations are flourishing in post-industrial Yorkshire because the water has become much cleaner.
“Anecdotally, in Victorian times before industrialisation, this area had a lot of dolphins,” he said. “There was a dolphin population in and around the Humber, for example, and these dolphins are probably a remnant of that population.
“They are ancestors of a much bigger population. They’re just coming back to areas that historically they did used to live in.”
But while many of the locals are delighted to see more dolphins arrive, they are being urged to treat them with respect.
“You shouldn’t approach them in a boat closer than 100 metres and you should never chase after them,” said Mr Petch. “People can be prosecuted for doing so.”