Guest blog by RSPB NI Tern Conservation Officer Monika WojcieszekFollowing my last blog in May, the birds’ breeding season is over at Blue Circle Island on the RSPB Larne Lough Islands reserve in Co Antrim. Fortunately, we were able to make several visits to follow up on the progress of this important seabird colony, which hosts Sandwich terns, common terns, a selection of gulls, oystercatchers, black guillemots and - the rarest breeding seabirds in Europe – roseate terns (pictured, above).In late May, we discovered that our earlier efforts to prepare nest boxes for roseate terns paid off and the only breeding pair in Northern Ireland had returned to Blue Circle Island; the birds had two eggs.
To monitor other species with larger numbers of nests, including common terns, we used the ‘pasta method’ (above). Using pre-counted bags of pasta, we marked each encountered common tern nest without risk of counting the same nest twice. By counting how many pasta pieces were left after the survey, we could quickly find out how many nests were on the island. Pasta is cheap, biodegradable, and often adult birds simply lift it off the nest like a pebble.During the breeding season, we also carried out regular biosecurity checks on the island to keep the chicks safe from mammalian predators. Blue Circle Island is part of the Biosecurity for LIFE programme that raises awareness of the threat of invasive predators and puts in place systems to prevent their accidental introduction to islands.Apart from providing an electric fence to keep larger mammals including otters away, we placed some cocoa-flavoured wax blocks (pictured, above) to monitor for rats and mice. We checked the baits regularly for any teeth marks that would alert us to the presence of rodents on the island. Rats can pose a real threat to any seabird colony. These capable swimmers can swim around one kilometre in calm waters, and can prey on eggs, chicks and sometimes even adults. It is therefore vital to prevent any accidental introduction of rats and other invasive species on Blue Circle Island.By late June, the island was covered with hundreds of young birds. Black headed-gull chicks were the first ones to fledge. Sandwich terns were also doing well, and many nearly-fledged chicks were gathering in large groups, called creches, waiting to be fed by the adults. At least one roseate tern chick was also present, looking healthy and well (below).
By late July Blue Circle Island grew quiet, with most of adults and fledged birds leaving the island behind. To our delight, the roseate tern chick also successfully fledged. The young terns will now spend some time on the Northern Ireland coastline, feeding in the rich waters of Irish Sea before starting their first perilous journey to their wintering grounds.
* To find out more about Biosecurity for LIFE and what members of the public can do to safeguard birds nesting on islands, visit https://biosecurityforlife.org.ukWe would like to thank the Blue Circle Cruising & Sailing Club at Magheramorne for allowing RSPB NI to keep the boat on their premises for the duration of the breeding season. This made our work much easier and it greatly reduced travelling times during COVID-19 movement restrictions. All photographs taken during monitoring visits under NIEA licence. Roseate tern pic (top) by Neal Warnock. All other pics by Monika Wojcieszek
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