They had been hoping for a nice day out on the bay. Instead, dolphin-watching tourists in Wales were confronted with the shocking and grisly sight of four adult bottlenose dolphins pursuing and killing a common dolphin calf.
The trip, in Cardigan Bay, was operated by Dolphin Spotting Boat Trips and the Sea Watch Foundation (SWF), a charity that monitors the dolphins in the bay to inform and advise on their conservation status and protection.
Dylan Coundley-Hughes, an intern with the SWF, was on the trip, on which tourists go dolphin-watching alongside experts who are photographing and collecting data on the cetacean population.
He said: “While conducting a boat survey on behalf of the Sea Watch Foundation aboard a dolphin-spotting wildlife tour, we observed intense splashing and dolphin activity. At first, we saw something flung into the air and suspected a porpoise, but to our disbelief it was a common dolphin calf, making this encounter an interspecific infanticide.
“I was filming for a personal documentary at the time and couldn’t believe I had captured such a rare behaviour between different dolphin species. It was both remarkable and heartbreaking to witness.”
The attack could have been prompted by competition for resources such as prey, experts from the SWF said.
A postmortem of the calf will be conducted by the UK cetacean strandings investigation programme, which may provide more information.
Katrin Lohrengel, who runs the SWF’s Cardigan Bay monitoring project, said: “Bottlenose dolphins have a very wholesome reputation, but many people are not aware that male dolphins have been known to commit infanticide; they kill bottlenose dolphin calves. They have also been documented killing harbour porpoises and often show aggression to other cetacean species.
“Both infanticide and ‘porpicide’ are known to occur in Cardigan Bay, but we have never witnessed interspecific aggression towards common dolphins before. While it’s not surprising that this behaviour is taking place, it’s very rare to witness it and even rarer to catch it on film.”
Bottlenose dolphins are common around the UK and are also often seen in the Moray Firth and off the coast of Cornwall. Common dolphins, sometimes referred to as short-nosed common dolphins, are usually smaller. They are highly social animals and are normally found in groups.
