Atlantic Puffin tagging report 2020, Skellig Michael

The Atlantic puffin (Fratercula arctica) is a seabird species found on several islands and high cliffs around the coast of Ireland. Puffins are typically monogamous and long-lived, with breeding delayed until 5 or 6 years old. A single egg is laid in early summer, which parents take turns incubating until it hatches, then taking turn provisioning the chick until it fledges in late July/early August. Once the breeding season is over, puffins migrate offshore until the next breeding attempt. Because of their low reproductive output, puffin populations are sensitive to impacts such as severe storms or oil pollution at sea, or invasive predatory species at the colony.

In the 2000s, rapid population declines led to the species being classified as Endangered in Europe by the IUCN. Despite the emblematic status of the puffin, our knowledge of their ecology in Ireland is limited, especially concerning their behaviour and distribution at sea.

Skellig Michael supports a population of breeding puffins. Puffins are a burrow nesting seabird making obtaining accurate estimates of population size difficult. No systematic census of puffins has been conducted on Skellig Michael, and previous estimates of population size are highly unreliable for monitoring purposes. A more rigorous approach for counting burrow-nesting seabirds has been recently developed by the Seabird Research Group in UCC. Consistent monitoring of the Skellig Michael breeding puffin population would be hugely informative for the management of the site. However, puffins are also susceptible to increased mortality during the non-breeding season, making it important to understand the migration patterns of this species.

In recent years, the advent of biologging technology has allowed us to fill some of the knowledge gaps of puffin ecology. Geolocator devices, weighing 1-2g were first deployed on Irish Atlantic puffins in 2010, when researchers from UCC attached tags to puffins on Skellig Michael. These devices record light levels, and the location of the bird can then be inferred from the timing of sunrise and sunset. The level of error in these location estimates is high, but broad-scale movements can be determined.

These first tagging efforts revealed that the Skellig puffins were travelling huge distances in the non-breeding season, with many individuals migrating across the Atlantic to the east coast of Canada. Puffins spent considerable time in the vicinity of the Mid-Atlantic Ridge, the Bay of Biscay and southwest of Ireland, with some entering the Mediterranean Sea towards the end of the non-breeding season. This was in stark contrast to the only previous geolocator study of puffins in the UK, which remained resident not far from the colony winter-long.

In July 2020, UCC’s seabird research group were once again permitted access to Skellig Michael to deploy geolocators on puffins to assess whether the overwintering migration once again. Tagging work was approved by the UCC animal ethics committee and conducted under permit from the National Parks & Wildlife Service and the British Trust for Ornithology. 20 devices were attached to leg rings on puffins. These will be retrieved over the next 2 summers, with a further 10-15 devices planned for deployment in 2021.