Arctic Tern

Irish Name: Geabhróg artach
Scientific name: Sterna paradisaea
Bird Family: Terns
amber
Conservation status

Status

Summer visitor from March to September to all Irish coasts. Winters off south Africa and as far south as Antarctica.

Identification

Usually seen over the sea. Slender seabird with narrow, pointed wings, long forked tail and long, pointed bill. Grey above and white below, dark cap to head. Flight light and buoyant, can hover briefly over the sea before diving in. Very similar to Common Tern (with which it breeds) and told apart by plumage and structure. Arctic tern is smaller, with a smaller head, neck and bill and slightly narrower wings, which look forwardly placed on the body. Very short legs. Adults have a blood red bill, usually with no dark tip. The underparts are greyer than Common Tern and there some contrast with the cheek. The wing pattern is useful in separation, Arctic terns shows no dark wedge in the primaries but shows a distinct trailing edge. Arctic terns have longer tail steamers, extending beyond the wing tips. Adult winter plumage, like all terns is different from breeding plumage, but is only seen in the wintering range. Also has distinctive juvenile plumage, with some brown in the mantle, a dark carpel bar and white secondaries. Shows a distinct trailing bar to the primaries, bill darkens rapidly.

Voice

Similar to Common Tern

Diet

Marine fish, crustaceans and insects.

Breeding

Mainly a coastal breeding bird, but in Ireland the species also breeds inland on the fresh water lakes of Lough Corrib (Co. Galway) and Lough Conn (Co. Mayo). More colonies are found on the west coast with Co. Wexford, Co. Kerry, Co. Mayo and Co. Donegal having the largest number of birds

Wintering

Considered to have the longest migration of all birds, utilizing the summer of both hemispheres.

Monitored by

All-Ireland tern survey in 1995, and through breeding seabird surveys carried out every 15-20 years, the last was Seabird 2000, which was undertaken between 1998 and 2002. Arctic Terns are also monitored annually at Rockabill and Ladys Island Lake

Blog posts about this bird

Arctic Tern

Dalkey Islands: tern numbers get a boost

The Dalkey fieldwork season began with a bang on the 15th of May. We suddenly went from weeks of longing for fieldwork, to frantically preparing all three islands (Dalkey Island, Lamb Island and Maiden Rock) for the returning tern colony.
Setting-up-canes-as-gull-deterrent-Dalkey-tern-colony-2020 Steve setting up cane grid on Lamb Island.
Thankfully, the birds played ball and we weren’t dodging eggs underfoot on the first two visits. Following on from last year, we laid out a grid of bamboo canes on Lamb Island. The canes were driven into the drought-stricken earth at an angle, at distances of 1 m apart. The concept was devised by Chris Redfern of the RSPB. Herring, Lesser Black-backed and Great Black-backed Gulls cannot fly between the canes to grab a quick egg or chick sized snack as their wing spans are greater than 1 m. The terns on the other hand, easily flit between the canes as their wingspan is less than 1 m.
Arctic-Tern-flying-between-canes-Dalkey-tern-colonyArctic Tern flitting between canes on Lamb Island. (Photo taken under NPWS licence).
Fencing was set up around the tern sub-colony on Dalkey Island. Nest boxes, which function as chick shelters, were rearranged. Gravel was added to boxes and likely nesting spots on Maiden Rock. The chick shelters on Dalkey Island are a little bit more avant garde. They consist of 75 cm lengths of pipe. This length will hopefully prevent and gulls and corvids gobbling up the chicks.
Arctic-Tern-chicks-using-chick-shelters-on-Dalkey-IslandChicks using pipe shelter on Dalkey Island (2019). (Photo taken under NPWS licence).
The next visit on the 26th of May was when the egg-citement (sorry!) really began, with 13 nests recorded on Lamb Island and 6 on Dalkey Island.
Tern-nest-eggs-Dalkey-tern-colonyTern nest. (Photo taken under NPWS licence).
Between the 2nd and 16th of June, 26 nests were found on Dalkey Island, of which 25 were still active on the 16th, more than triple the 7 nests recorded across Dalkey Island last season! The first Arctic Tern chick of the season was recorded on the 8th of June, with a second egg in the clutch hatching.
First-Arctic-Tern-Chick-Dalkey-Tern-Colony-2020A tiny beak can be seen poking out of the darker egg! (Photo taken under NPWS licence).
Lamb Island is also faring well, with 19 active nests recorded. Unlike last season when only Arctic Terns nested on the island, at least two Common Tern pairs have been spotted on Lamb Island. Chicks were first recorded on the island on the 11th of June and are getting bigger and bolder by the day.
Close-up-Arctic-Tern-Feeding-Chicks-Dalkey-Tern-ColonyArctic Tern feeding chick. (Photo taken under NPWS licence).

A total of five tern nests (both Common and Arctic) and two Oystercather nests have been recorded on Maiden Rock this season. During the third nest census I was surprised to find that in addition to tern eggs one nest now also contained two Oystercatcher eggs!

Mixed-Oystercatcher-and-tern-nest-Dalkey-tern-colony-2020Oystercatcher (larger) and tern eggs in single nest. (Photo taken under NPWS licence).
Unfortunately however, between the 3rd and 4th nest censuses a combination of predation and sea surges resulted in all but one tern nest failing on this small island. Our fingers are crossed for this final pair! On Dalkey and Lamb Islands though, things are looking bright for the small tern colony. We're still miles from the finish line, but Arctic and Common Terns are super-star parents! Just ask the Jackdaw below and this very bruised field worker, about the lengths these birds will go to, to protect their young! Although nothing is certain in conservation, the chicks at least are in a safe pair of wings.
Arctic_Tern_chasing_Jackdaw_Dalkey_tern_colony_2020Arctic Tern chasing a Jackdaw off of the colony. (Photo taken under NPWS licence).
Marine

Arctic Tern chicks take flight on Dalkey Island

For the first time on record, this year Arctic Terns have successfully raised chicks on the main island of Dalkey, south Co. Dublin, giving the vulnerable colony, which is protected by BirdWatch Ireland, a much-needed lift. So far six chicks have taken to the wing from the island, with a seventh expected to take its first flight over the next few days. This is much a needed triumph, as although Arctic Terns have in the past successfully reared young on both Maiden Rock and Lamb Island (also part of the Dalkey Island archipelago), prior to this year chicks have never survived to take flight, or “fledge”, on Dalkey Island itself. This is most likely due to the effect of predators, and combined with unseasonable weather regularly flooding the other two islands in the archipelago, there were great concerns for the future of this dwindling Arctic Tern colony. Conservationists’ efforts to remove at least a large proportion of the rat population on Dalkey Island, paired with the tenacious protection of the tern parents, have allowed these chicks to survive and take flight. On top of the success on Dalkey Island, Lamb Island has also confirmed six fledglings, but the true figure is thought to be higher. A further nine chicks are currently waiting in the wings. The Arctic Tern, nicknamed ‘sea-swallow’ after its long tail streamers and buoyant flight, is the world’s greatest long-distance traveller, migrating further than any other animal. During our summer months, they breed in Ireland and other areas of the Northern Hemisphere and then fly all the way to the Southern Ocean, off Antarctica, where they wait out the northern winter. This means that they see more daylight each year than any other creature on the planet. Throughout the course of their lives Arctic Terns can travel more than 3 million kilometres; an especially impressive achievement for a bird that weighs just 100 grams. To put the overall distance which these birds travel into context, they migrate the equivalent of almost 4 round trips to the moon over the course of their lives (25 – 30 years). “All of us at BirdWatch Ireland are thrilled with how well this small but resilient colony has done this year,” said Tara Adcock, BirdWatch Ireland’s Dalkey Tern warden. “Prior to this season, chicks surviving past two weeks, never mind fledging from Dalkey Island itself, was unheard of! This is thanks to management from BirdWatch Ireland staff and volunteers, support and funding from the EU LIFE Roseate Tern Recovery Project and Dun Laoghaire – Rathdown County Council, advice from the RSPB and the tenacity of the Arctic Tern parents themselves. “This project truly shows that if you give nature a chance, it can bounce back. It has been a real pleasure to work to protect these phenomenal birds. It’s incredible to think that in a few weeks, these chicks along with their parents will undertake the longest migration in the natural world, all the way to the Antarctic!” Arctic Terns are Amber-listed on the list of Birds of Conservation Concern in Ireland, meaning that they are a particularly vulnerable species. One of the reasons for this is that the availability of suitable breeding habitat, namely undisturbed rat- and mink-free offshore islands, is quite limited. To tackle this, BirdWatch Ireland carried out rat-baiting across Dalkey and Lamb Island before this year’s nesting season. Canes were also erected across a portion of Lamb Island to exclude gulls from the tern colony. This work was carried out as part of the Dalkey Tern Conservation Project, which is funded by the EU LIFE Roseate Tern Recovery Project and Dún Laoghaire–Rathdown County Council. With continued management and funding we hope to see this small but mighty tern colony flourish over the coming years, growing in capacity from its current level of 29 pairs. It is also hoped that eventually another species, the elegant Roseate Tern, one of Europe’s most endangered seabirds, will also be persuaded to nest at Dalkey. Europe’s largest colony of Roseate Terns (holding approximately 50% of Europe’s breeding population) is on Rockabill Island, off the coast of north Co. Dublin, so the birds would not have far to travel. Roseate Terns prefer to nest in colonies where other tern species are already established, so the presence of a thriving Arctic Tern colony at Dalkey could prove very attractive for them. By providing these birds with multiple nesting habitats, such as at Dalkey, we can help to safeguard their future.

Similar Species

Common Tern

Irish Name:
Geabhróg
Scientific name:
Sterna hirundo
Bird Family:
Terns

Roseate Tern

Irish Name:
Geabhróg rósach
Scientific name:
Sterna dougallii
Bird Family:
Terns