Encounters with common dolphins off the west of Scotland have more than doubled over a decade , according to experts . And now research is under way to find out why , with scientists proposing that climate change may have caused the surge in numbers . Common dolphins were once a rare sight in the Hebrides , preferring warmer waters found further south , leading experts to believe that global warming has led to pods moving north . Encounters with common dolphins ( a stock image is shown ) off the west of Scotland have more than doubled over a decade , according to a leading research body . Monitoring by Hebridean Whale and Dolphin Trust teams has seen the number of encounters increase by 68 per cent over the past 12 years . Monitoring by Hebridean Whale and Dolphin Trust teams has seen the number of encounters with common dolphins increase by 68 per cent over the past 12 years . The dolphins come to the Hebrides in spring to take advantage of seasonal food stocks , travelling in large groups and sometimes forming ‘ super-pods ’ of thousands of individuals . The species , which are smaller than the area ’ s resident bottlenose dolphins , often approach boats and play in the wake , the trust said . While they were once drawn to warmer waters above 10°C south of the area , climate change is causing sea surface temperatures in the Hebrides to rise by around 0.5 °C a decade . And warmer water species appear to be colonising new areas further north or closer to shore , the trust said . The dolphins are moving further north than they did decades ago , possibly because the water has become warmer . While the shift could create new feeding opportunities for the common dolphins , it could increase competition between other types of dolphin or seabirds . An Oystercatcher on the Isle of Mull is shown . The shift north could be creating new opportunities for the common dolphins to find food in new areas , but may mean the species is competing for fish with other types of dolphin or seabirds . Volunteers will live , work and sleep on Silurian research ship for up to 12 days . They will receiving training and work with scientists to conduct visual surveys , acoustic monitoring using specialist equipment , and cetacean identification through dorsal fin photography . They will also help run Silurian - giving them a chance to learn to sail and navigate . Areas covered depend on the weather but will range from Mull of Kintyre in the south , Cape Wrath in the north and St Kilda in the west . These seas are one of Europe ’ s most important cetacean habitats . Participation costs range from £683 to £1,500 to cover boat expenses , accommodation , training , food and insurance , and support the trust ’ s research . More information can be found at HWDT . Colder water species such as the white beaked dolphin could be forced to retreat further north , and while the trust said it had found no evidence of the white beaked dolphin being displaced , continued monitoring of the situation is needed . The charity is calling for volunteers to join its research vessel Silurian to help conduct visual surveys and acoustic monitoring and identification of cetaceans . This includes dolphins , whales and porpoises . Dr Conor Ryan , sightings and strandings officer at Hebridean Whale and Dolphin Trust said : ‘ An increase in common dolphins means that those wishing to encounter dolphins in the wild are in luck - but further research is needed to explain why this is happening , the extent to which it has been caused by human activity and the implications for other cetacean species. ’ Kerry Froud , the trust ’ s biodiversity officer , added : ‘ Our research expeditions depend on volunteers . ‘ In return they offer the opportunity of a lifetime to contribute to a better understanding of cetaceans and basking sharks , whilst enjoying the beautiful scenery of Scotland ’ s west coast and experiencing exhilarating sailing . The charity is calling for volunteers to join its research vessel Silurian to help conduct visual surveys , acoustic monitoring and identification of cetaceans - which include dolphins , whales and porpoises - as well as helping to run the yacht . A stock image of the crew of the yacht is shown . Areas that will be covered in the forthcoming survey depend on the weather but will range from Mull of Kintyre in the south , Cape Wrath in the north and St Kilda in the west ( all marked on the map )
Common dolphins were once rare in the Hebrides , preferring warmer water . But their numbers have risen by 68 per cent over the last 12 years . The Scottish Government has been working with local authorities to try and protect them from further damage caused by climate change - but it is not clear how much of a difference this will make for them. Hebridean Whale and Dolphin Trust is recruiting volunteers for monitoring .