The Atlantic puffin (Fratercula arctica) is a pelagic seabird that spends the vast majority of its life at sea. However, for a specific period each year, Skellig Michael becomes one of the most significant terrestrial breeding sites for this species in Ireland. The seasonal presence of these birds is dictated by a rigid biological calendar, influenced by North Atlantic weather patterns, food availability, and the requirements of the breeding cycle. Understanding this timeline is essential for any researcher or visitor interested in the avian ecology of the UNESCO World Heritage site.
Skellig Michael puffins arrive in large numbers, often exceeding several thousand pairs, to occupy the steep, grassy slopes and rock crevices of the island. Their arrival and departure are punctuated by dramatic physical and behavioural changes that align with the shifting seasons of the Atlantic.
Late March and April: The Return from the Atlantic
Throughout the winter months, puffins are entirely absent from the Irish coastline. They lead a solitary existence on the open ocean, dispersing across the North Atlantic. During this pelagic phase, the birds undergo a moult, losing their distinctive colourful beak plates and the vibrant patches around their eyes. By the time late March arrives, the puffins begin to congregate in the waters surrounding Skellig Michael.
This period marks the beginning of the transition from sea to land. Before making landfall, the puffins must regain their breeding plumage. The beak increases in size and develops its characteristic orange, blue, and red segments. This serves as a primary visual signal for mate selection and social hierarchy within the colony.
The first landfalls usually occur in early to mid-April. Initially, the birds are cautious, spending hours on the water in "rafts" before eventually flying up to the precipitous cliffs. Once on the island, they return to the same burrow sites used in previous years. Puffins are generally monogamous, and the reunion of pairs often takes place at the entrance of these burrows. This is an active period of social re-establishment, where billing: the rubbing together of beaks: is frequently observed as a pair-bonding behaviour.
May: Burrow Preparation and Incubation
By May, the colony is fully established. The primary focus shifts from social interaction to the arduous task of preparing the nesting site. Puffins on Skellig Michael typically utilise the deep soil layers found on the lower and middle slopes of the island. They either excavate new tunnels using their sharp claws or renovate existing burrows, some of which may have been occupied by Manx shearwaters or rabbits in the past.
The anatomical structure of the puffin's feet is specifically adapted for this purpose. The strong, orange-coloured legs are positioned far back on the body, providing the necessary leverage for digging into the peat-heavy soil. A single egg is laid per pair, typically in the latter half of May. The incubation period lasts approximately 39 to 45 days. Both the male and female share the responsibility of incubation, tucking the egg under one wing and resting their body against it to maintain a consistent temperature.
During this stage, the island appears relatively quiet compared to the later months. One adult remains underground with the egg while the other forages at sea. This ensures the egg is never left vulnerable to predators such as the Great Black-backed Gull, which constantly patrols the skies over the Skelligs. Visitors taking a Skellig Michael boat tour during this month will observe the birds standing sentry outside their burrows, but the high-frequency foraging flights have not yet reached their peak.
June and July: Peak Activity and Chick Rearing
The hatching of the eggs in June triggers a significant shift in the energetics of the colony. The arrival of the "puffling": the colloquial term for a puffin chick: demands a constant supply of high-protein food. For the next five to six weeks, the adult puffins are engaged in a relentless cycle of fishing and delivery.
The primary food source for Skellig Michael puffins is the sand eel (Ammodytes). The puffin’s beak is uniquely evolved to carry multiple fish at once; small serrations on the upper mandible and a specialized tongue allow the bird to hold a dozen or more sand eels while continuing to hunt for others. It is not uncommon to see a puffin returning to the island with a beak overflowing with silver fish.
This period is the most active time for any Skellig Michael tour. The air is filled with birds returning from the foraging grounds, often flying at high speeds to avoid "kleptoparasitism": a behaviour where gulls or skuas intercept the puffins to steal their catch. The sheer density of avian life during June and July is a testament to the productivity of the surrounding Atlantic waters. Those who undertake the 600-step challenge will pass directly through the heart of the puffin habitats, where the birds are often seen resting on the stone steps or the remains of the monastic walls.
August: The Fledging and Departure
The month of August brings the conclusion of the breeding season and the most perilous phase for the young pufflings. Unlike many other seabirds, puffin chicks are not fed by their parents right up until they leave. As the chick reaches full size, the parents gradually decrease the frequency of feedings.
The fledging process on Skellig Michael is a strictly nocturnal event. To minimize the risk of predation by gulls, the pufflings emerge from their burrows under the cover of darkness, typically during the first two weeks of August. They make their way down the steep slopes and launch themselves into the Atlantic. Once they reach the water, they swim away from the island as quickly as possible. These young birds will remain at sea for several years before returning to land to breed for the first time.
By mid-August, the adult population follows suit. The departure is sudden; an island that was teeming with thousands of birds can become almost entirely devoid of puffins within a matter of days. The colourful beak plates are shed, the vibrant eye markings disappear, and the birds return to their muted winter plumage. They depart the Irish coast and head back to the open ocean, ending their terrestrial residency until the following spring.
The Wintering Phase: Survival in the North Atlantic
While the puffins are absent from Skellig Michael from September to March, their life remains a subject of intense scientific interest. Modern tracking technology has revealed that the Skellig Michael population disperses widely. Some birds remain in the Celtic Sea or move south toward the Bay of Biscay, while others undertake a trans-Atlantic journey, wintering as far west as the coast of Newfoundland and Greenland.
During this time, the puffins must endure the harsh conditions of the North Atlantic winter. They are subject to the whims of severe storms and must find sufficient food in a vast, unpredictable environment. The survival of the adults during this pelagic phase is critical for the stability of the Skellig Michael colony, as the low reproductive rate: one egg per year: means the population cannot recover quickly from high adult mortality.
Conservation and the Future of the Colony
The Atlantic puffin is currently listed as a vulnerable species. While the colony at Skellig Michael remains relatively robust, it is not immune to global environmental pressures. Changes in sea temperatures can alter the distribution of sand eels, forcing the puffins to travel further for food, which in turn impacts the survival rate of the chicks.
The management of human activity on the island is a vital component of puffin conservation. Visitors departing from Portmagee Marina are instructed to remain on the designated paths to avoid collapsing the fragile burrows. The UNESCO status of the island ensures a level of protection that is unparalleled, yet the responsibility for stewardship lies with every individual who visits. For more information on the broader ecosystem, the guide to the birds of the Skellig Islands provides further detail on the other species that coexist with the puffins.
The seasonal rhythm of the puffin calendar is a foundational element of the Skellig Michael experience. From the first colourful arrivals in April to the silent departures in August, these birds define the natural character of the island. Observation of this cycle requires an appreciation for the clinical precision of nature and a commitment to preserving the environment that supports such a complex biological programme.