Record UK numbers of the critically endangered Balearic Shearwater arrive in Devon waters
The Balearic Shearwater is a critically endangered seabird endemic to the Balearic Islands in the western Mediterranean, and is in steep decline, with fewer than 3000 breeding pairs remaining, though the total population including non-breeding birds was last estimated at around 22,000 individuals. In recent years, increasing numbers of post-breeding Balearic Shearwaters birds have shifted north from traditional moulting grounds in the Bay of Biscay to the English Channel, coinciding with warming sea temperatures and northward shifts in Anchovies and other pelagic fish food sources. South west England waters are now considered internationally important at times, with counts of over 1000 made in Devon, most recently 1,145 at Berry Head in September 2023 (a national record) and 1068 at Start Point in July 2020. Boat surveys by the charity MARINElife and satellite tagging work by others have confirmed these birds are not just passing through but are actively using the waters as moulting and feeding grounds for weeks on end.
Increasing numbers of Balearic Shearwaters had been recorded in south west England waters from coastal headlands in the days leading up to the survey, so expectations were high of seeing some birds on 24th July. However, the number of sightings of this species on the 24th were extraordinary and unprecedented, with over 30 feeding or resting flocks detected, spread across all sea areas surveyed, an area of 240 km2. Given that only a tiny fraction of Lyme Bay was sampled (less than 1%), it seems likely that were hundreds to many thousands more birds were present, representing a high proportion of the world’s population.
Professor Tom Brereton, Marinelife’s Research Director who conducted the survey, said, “The south west marine environment is changing rapidly from plankton communities at the base of the chain, through to top predators such as Balearic Shearwaters. We must act quickly to ensure that species such Balearic Shearwater, Bluefin Tuna and other new arrivals are adequately protected whilst in our waters.”
Major threats to Balearic Shearwaters include: accidental drowning in fishing nets, invasive predators (rats, cats) at breeding sites and climate change (shifting prey, storm mortality). Of concern, one bird was found entangled by sea angling gear on the 24th July survey, highlighting the bycatch issue.

Balearic & Manx Shearwaters © Tom Brereton

Ocean Sunfish © Tom Brereton

Common Dolphin © Tom Brereton

White-beaked Dolphins © Tom Brereton
The Balearic Shearwater sightings were only one highlight of an extraordinarily rich day for marine wildlife encounters, with a mix of familiar species and ones much rarer and brought in by warming sea temperatures here and elsewhere. Highlights included unusually large numbers of (formerly rare) Crystal Jellyfish, an Ocean Sunfish, three pods of Rissos’ Dolphin and large numbers of Common Dolphin. Risso’s Dolphin have been sighted in unprecedented numbers off the south west coast this summer, following a large influx of Mediterranean Octopus, a known prey item. Hundreds of Manx Shearwaters, Gannets, Kittiwakes and Guillemots have also been recorded.
Andy Tucker, Managing Director of Naturetrek and the Operations Manager of the Lyme Bay Day Trip, said, “We are delighted to be able to offer an ideal means for this essential data to be collected, contributing to vital research on this endangered species – one that is even rarer and more threatened with extinction than the Polar Bear – all whilst giving our wildlife-watching clients a superb day out.”
We have just a handful of spaces remaining on our last two Lyme Bay cruises of the year, departing on Tuesday 16th September and Wednesday 1st October. To find out more, or to book your place, please visit our 'Seabirds & Cetaceans of Lyme Bay' tour page or call us on 01962 733051.