The earlier-than-usual departure of nesting puffins from Skellig Michael, off the Co Kerry coast, this year has left birdwatchers and the National Parks and Wildlife Service (NPWS) confused.
The NPWS said in a statement: “While there is some evidence to suggest that the puffins left the island a few days earlier than in previous years, we do not yet know why this has occurred.”
The service said the departure does not “suggest any big change in the behaviour pattern of the population on this island or at other colonies”. Survey data, carried out by the NPWS since May of this year, showed “favourable” numbers when compared with previous surveys dating back to the 1990s, it said.
Valerie O’Sullivan, a photographer who recorded the departing puffins for the NPWS, said the breeding season on the island, which normally starts around April, seemed successful and may have began earlier than usual this year. She said “the tradition is that they leave before the Puck Fair”, which takes place from August 10th to 12th in the town of Killorglin.
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Skellig Michael, a Unesco world heritage site, lies about 12km off the Kerry coast and was a 6th century monastic site. Its popularity increased after it featured in Star Wars Episode VII: The Force Awakens and Star Wars Episode VIII: The Last Jedi.
Puffins nest in burrows or in cracks and crevices across the island, which offer protection from avian predators. Adult pairs tend to desert their young on the island as soon as possible, forcing the chicks to fly off in search of food. They spend the winter months bobbing around in the North Atlantic, feeding on fish in the cold waters.
Niall Hatch of Birdwatch Ireland said this year’s early exodus did not appear to signal any particular problem. Fish seemed to be in abundant supply but Mr Hatch said the plankton that many species feed off are very susceptible to climate change and warming seawaters, which could be problematic.
“The puffins have a large beak to bring fish back to their nest and a range of about 50km in which to search for food. But if the plankton move further north in search of cold water, the fish will follow them so we have concerns for the puffins in the long-term,” he said.
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David Walsh, who operates a boat named The Force Awakens out of Ballinaskelligs, said landings of tourists on the island are strictly controlled, with just 15 boats licensed to take people on to the island. Each boat is allowed to bring just 12 passengers once a day.
He said boats were given time slots so as to ensure that not too many people were on the island at once and poor weather this year would have reduced the numbers visiting.
The Office of Public Works, which manages the island, said puffins are typically monogamous and long-lived, with breeding delayed until they are five- or six-years-old. A single egg is laid in early summer, which parents take turns incubating until it hatches. They then take turn feeding the chick until it fledges in late July or early August.
“Once the breeding season is over, puffins migrate offshore until the next breeding attempt,” it said.
No systematic census of puffins has been conducted on Skellig Michael and previous estimates of population size are seen as unreliable for monitoring purposes. A more rigorous approach for counting burrow-nesting seabirds has been recently developed by the Seabird Research Group at University College Cork. The results of this are expected in the next few years.