Common Tern
| Irish Name: | Geabhróg |
| Scientific name: | Sterna hirundo |
| Bird Family: | Terns |
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Conservation status
Conservation status
Status
Summer visitor from March to October to all Irish coasts.
Identification
Usually seen over the sea or over large inland lakes. 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 Artic Tern (with which it breeds) and told apart by plumage and structure. Common Tern has a longer head and bill and slightly broader wings, which look central on the body. Adults have a orangey red bill, usually with a small dark tip. Underparts are whiter than Artic Tern and there is no contrast with cheek. The wing pattern is useful in separation, Common tern shows a dark wedge in the primaries which develops over the summer and a defuse bar to the trailing edge of the primaries. Common terns have shorter tail steamers, not extending beyond the wing tips. Adult winter plumage, like all terns is different from breeding plumage and can develop in the summer months. Has a white forehead, all dark bill and dark carpel bar. Also has distinctive juvenile plumage with gingery mantle, a dark secondary bar and dark carpel bar. Bill base is orange. Shows a diffuse trailing edge to the primaries. First and second summer plumages are rarely seen in Europe.
Voice
A noisy bird when breeding, giving a rapid series of quarrelsome calls.
Diet
Chiefly fish.
Breeding
Nest colonially on the ground from August to October. Breeds on the coast, with larger colonies in Co. Dublin, Co. Wexford and Co. Galway. Also breeds inland on islets in freshwater lakes, notably in Co. Galway and in Co. Mayo.
Wintering
Winters in west and south Africa.
Monitored by
All-Ireland Tern Survey in 1995, and through breeding seabird surveys carried out every 15-20 years. Common Terns are also monitored annually at Rockabill and Lady’s Island Lake.
Summer visitor, breeding on inshore islands and undisturbed beaches.
Wintering in West Africa.
Blog posts about this bird
Ups and Downs for Galway Terns in 2025
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For the past six years, Conservation Volunteers Galway and staff at the Atlantic Technological University have been protecting and monitoring nesting Common Terns in Galway City, to great success. The team have installed three rafts in Lough Atalia, designed to provide safe nesting habitat as an alternative to local sites that are subject to disturbance and predation. In recent years we have been delighted to be invited to assist them in their work by ringing the Terns so that we can find out more about them – their survival rates, where they go after leaving Galway, what other colonies they're linked to, and more. This year the ringing work has been co-funded by Galway City Council and the National Parks and Wildlife Service under the Local Biodiversity Action Fund and we are very grateful to them for making this work possible.
From early May we had reports from Peter, Dan (Conservation Volunteers Galway) and Ian (ATU) that the Terns were back and nesting on the artificial floating platforms they’ve been deploying annually in Lough Atalia, beside Galway City. Each platform has UV protected clear polycarbonate walls to keep out any predators that might swim out, and though there are gulls in the area and they occasionally land on the platforms, the Terns do a good job of seeing them off once they return in late April.
For the past six years, Conservation Volunteers Galway and staff at the Atlantic Technological University have been protecting and monitoring nesting Common Terns in Galway City, to great success. The team have installed three rafts in Lough Atalia, designed to provide safe nesting habitat as an alternative to local sites that are subject to disturbance and predation. In recent years we have been delighted to be invited to assist them in their work by ringing the Terns so that we can find out more about them – their survival rates, where they go after leaving Galway, what other colonies they're linked to, and more. This year the ringing work has been co-funded by Galway City Council and the National Parks and Wildlife Service under the Local Biodiversity Action Fund and we are very grateful to them for making this work possible.
From early May we had reports from Peter, Dan (Conservation Volunteers Galway) and Ian (ATU) that the Terns were back and nesting on the artificial floating platforms they’ve been deploying annually in Lough Atalia, beside Galway City. Each platform has UV protected clear polycarbonate walls to keep out any predators that might swim out, and though there are gulls in the area and they occasionally land on the platforms, the Terns do a good job of seeing them off once they return in late April.
One of the artificial pontoons deployed in Lough Atalia to ensure Common Terns have somewhere safe and reliable to nest. Photo: Brian Burke.
Our first ringing visit took place in late May when most Common Tern pairs were more than halfway through the incubation period for their eggs. This was our first time to ring adult Terns in Galway. Small cage traps were carefully placed over nests, the ringing team moved away on the boat, and returned around 15 minutes later to take the birds out, ring them and quickly release them so they can go back to incubating their clutch again. BirdWatch Ireland do this sort of ringing at other colonies including Rockabill Island and Dublin Port to great success. While ringing chicks is useful and informative, it takes a few years for the chicks to return to the colony, whereas by ringing adults you can start to gather data much more quickly. We are hoping this ringing project will help us learn about the survival rates of the Galway Common Terns, their fidelity to the same platform and nest site, links with other colonies, as well as sites they use on their migration. We are using green colour rings with three numbers beginning with ‘6’ and a full stop, and these rings are also being used on Common Terns on Lough Ree in a project with the National Parks and Wildlife Service there, and will possibly be used at other sites in the west in the years to come.
One of the Common Terns nesting at Lough Atalia - caught and ringed under NPWS licence, and quickly released to return to the colony. The green coded ring is visible from a distance and will help us identify this individual in the future. Photo: Brian Burke.
In total we caught 14 adult Common Terns on this trip, almost all of which were not previously ringed, though the final bird of the day was sporting a metal BTO ring on its left leg. We added one of our colour rings so this bird can be more easily monitored in the future, and then very quickly sent the ring number off to the BTO to find out where and when it had come from! We were able to quickly check that it wasn’t from any of the NPWS or BirdWatch Ireland tern ringing projects on the east coast, and the chances of it being a Galway bird seemed slim even though a small number of tern chicks had been ringed in Galway in recent years. It turns out this bird was originally ringed as a chick in July 2006, making it 19 years old! While Common Terns can live to their late 20’s, the vast majority are under 10 years old. If they survive beyond that they’re doing well, and to reach nearly 20 years old is fantastic! This individual was ringed in Cork Harbour as a chick – another colony on artificial structures in an urban port area. For context, the oldest Common Tern on record in Ireland was 23 years old.
This Common Tern, nesting in Lough Atalia in Galway in 2025, was originally ringed as a chick in Cork Harbour in 2006, making it 19-years old. Photo: Emily Marsh.
Conservation efforts at individual colonies like Lough Atalia, Cork Harbour, Dublin Port, Rockabill, Lady's Island and elsewhere not only benefit that specific colony, but ensure there are more juvenile birds to spread to and help bolster and grow other sensitive colonies in other areas. Catching this bird was the icing on the cake of a successful day. The total number of nests present on this visit was 42 which was a very healthy number and really speaks to the success of this project by Galway Conservation Volunteers. The first chicks started hatching in the last week of May and our intention was to make another visit to ring the chicks in late June before they fledged. Unfortunately the team in Galway reported that the colony was hit by what was suspected to be avian flu shortly after, resulting in the loss of almost all chicks, and many adults. This outbreak has been devastating for the project team at Conservation Volunteers Galway, Atlantic Technological University and us at BirdWatch Ireland. This colony was hit by avian flu in 2023 alongside many other tern and gull colonies in Ireland and the UK, thankfully in 2024 there was no sign of avian influenza at the colony and an estimated 60 chicks fledged. Despite the negative end to this season, we shouldn’t forget how successful this project has been to date. Terns had struggled to nest successfully in inner Galway Bay due to predation and disturbance, and these platforms provided them with somewhere safe and reliable to nest. All we can hope now is that enough adults abandoned the colony without having caught avian flu and will survive to return next year. There will also be some young birds born here in recent years who are not yet old enough to breed, that will hopefully return in 2026 and beyond. The spread and impacts of avian flu only further underscore the importance of conservation projects like this, and we hope through continued ringing studies we can better evaluate the linkages between colonies to learn about the spread of avian flu and the hopeful recovery of the Common Tern population.The Common Tern colour-ringing project at at Lough Atalia is co-funded by Galway City Council and the National Parks and Wildlife Service under the Local Biodiversity Action Fund. A special thanks to Galway City Biodiversity Officer Paula Kearney for her help and support with the project and to Emily Marsh for assistance with ringing.
Funding for the Lough Atalia Tern Conservation Project, by Conservation Volunteers Galway, has been provided by Atlantic Technological University, The Heritage Council, Galway Atlantaquaria, Galway City Tidy Towns and public donations.
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Devastating Bird Flu impacts on Irish seabirds revealed in new study
A new study has revealed the devastating toll of the 2023 bird flu outbreak on Ireland’s tern species at their most important colonies, with Common Terns in particular suffering huge losses.
The recent highly pathogenic avian influenza (HPAI) H5N1 outbreak was the worst ever seen in Ireland, the UK and Europe. Details of the 2023 outbreak in Ireland, the number of birds that died at key breeding colonies, and the effect it has had on nesting numbers in 2024, have been published in the journal Bird Study by staff of BirdWatch Ireland and the National Parks and Wildlife Service. It focuses on colonies in Dublin (Rockabill Island, Dublin Port, Dalkey Island) and Wexford (Lady’s Island Lake) which have been subject to successful conservation efforts for decades, and the bird flu outbreak has come as a huge setback.
The full study entitled "A case study of the 2023 highly pathogenic avian influenza (HPAI) outbreak in tern (Sternidae) colonies on the east coast of the Republic of Ireland" was published in the journal Bird Study and can be accessed here.
A BirdWatch Ireland Tern Warden removes dead birds during the 2023 avian flu outbreak.
Common Terns suffered very high mortality across all colonies in 2023, with over 700 adult birds and over 1,100 chicks found dead by wardens in colonies at Rockabill, Dublin Port and Lady’s Island Lake. Many more will have died at sea and elsewhere along the coast and not been found, and a census of nests this year recorded a devastating loss of 1,250 breeding pairs across the colonies. In the case of Dublin Port, the colony was halved in a single year, representing the lowest number of nests in 19 years, and similarly the lowest on Rockabill Island since 2003. “The experience of visiting the colony during the outbreak and seeing so many dead and dying birds was really difficult,” said Helen Boland, manager of the Dublin Bay Birds Project. "We’re used to visiting the colony when it’s full of life, so to see so many lost in such a short space of time really had us worried about the future of the species. Terns are long-lived birds that only lay a small number of eggs per year, so losing adult birds is much more damaging to the population than having a bad breeding season.”
Arctic Tern. Photo: Kevin Murphy
Arctic Terns were down by 160 breeding pairs, a 20% decline, across the colonies this year due to avian flu. The small colony at Dalkey Island suffered complete breeding failure early in summer 2023 due to rat predation, and this appears to have saved them from contracting avian flu as the birds had deserted before the virus reached Ireland. Arctic Terns lead a very challenging life, not just when trying to find safe places to nest on the Irish coast, but they migrate to Antarctica in the winter – a round trip of nearly 100,000km per year. They have been struggling to nest successfully at some key colonies in recent years, largely due to predation. This, coupled with the fact that Arctic Terns lay fewer eggs than Common Terns, means their recovery is expected to be much slower. Ireland holds 95% of the entire European population of the rare Roseate Tern, concentrated at Rockabill island in Dublin and Lady’s Island Lake in Wexford. Having so many birds at only two sites makes them particularly vulnerable to problems like disease, and their only colony in Britain had already been hit by bird flu in both 2022 and 2023. Despite 65 adult birds and 135 chicks being found dead in Irish colonies during the 2023 outbreak, this didn’t translate into significant losses this year; Lady’s Island was down by 31 pairs, but Rockabill managed to increase by 75 pairs. “The Roseate Tern numbers this year were a pleasant surprise and higher than we expected considering the losses we know came from avian flu,” said Dr. Steve Newton, BirdWatch Ireland’s Senior Seabird Conservationist. “It seems that the high number of chicks fledged in recent years means that recruitment of young birds into the colony was higher than the number of birds lost to bird flu. We’re still expecting to see slow or stalled population growth in the next few years, but it could have been much worse for the Roseates." The Sandwich Tern is Ireland’s largest species of tern, and over 1,500 pairs nest in Wexford. Sandwich Tern colonies all over the UK and Europe were hit with avian flu in 2022, but the virus didn’t reach Irish colonies that year. Nesting numbers last year indicate that Irish Sandwich Terns had suffered mortality on migration and in the wintering grounds however, with a loss of 300 pairs. It is assumed the remaining birds had developed some level of immunity to the virus and therefore escaped summer 2023 relatively unscathed, and actually bounced back to pre-flu numbers this year. This provides some encouragement that the birds can bounce back quickly, though it may simply be that the increase in birds is a result of immigration from other colonies.
Roseate Terns: Photo: Brian Burke.
Conservation staff of BirdWatch Ireland and NPWS began summer 2024 with a sense of trepidation that bird flu might return, but thankfully there were no signs of it in any of the colonies and most managed to have a successful breeding season this year. With only half the number of nesting pairs it had in 2023, the Dublin Port Tern colony had its most successful breeding season ever, with most pairs managing to fledge two chicks. Elsewhere, Roseate Terns at Rockabill did well, fledging at least one chick on average per pair. The Common Terns at Rockabill, and all tern species at Lady’s Island fared ok but generally faced problems with predation by gulls and foxes, amongst other species, and their greatly reduced numbers may have left them more vulnerable to predation. The long-term tern conservation work by BirdWatch Ireland and the National Parks and Wildlife Service, and long-term support from Dublin Port Company, mean we are well-placed to facilitate recovery at the east coast tern colonies, but avian flu likely impacted west-coast and inland tern sites too. The colonies discussed here are the most important ones nationally for these four tern species and the impact of avian flu emphasizes the importance of not having ‘all of our eggs in one basket’. BirdWatch Ireland’s new Strategy outlines our intention to expand our work to inland and west-coast tern colonies and help secure the status of these species all over the country. Despite calls from BirdWatch Ireland, the Republic of Ireland has yet to develop a formalised plan for the monitoring and management of HPAI in wild birds. The role of various state agencies in such an outbreak is not clear, with some seemingly prioritizing impacts on livestock, others on potential public health implications, but little in the way of monitoring and managing the impact on wild birds. In the absence of comprehensive guidelines, regular meetings between BirdWatch Ireland and the NPWS proved invaluable in 2023. These meetings facilitated a comprehensive and adaptive approach as new guidance emerged from authorities in the UK and Europe and as the HPAI situation developed. It also allowed for a range of precautions to be implemented to minimise the risk of spreading the virus within or between colonies, or to people, while maintaining conservation efforts and long-term monitoring. This paper makes several key recommendations for future HPAI management and procedures in Ireland. It calls for the establishment of a more direct relationship between DAFM, NPWS and BirdWatch Ireland to allow for a more strategic response to outbreaks; the clarification of roles and responsibilities across all relevant government bodies; better resourcing to manage outbreaks and an increase in annual monitoring at Irish seabird colonies wherever possible to help ensure that threats such as HPAI can be monitored in real-time. It is vital that changes are enacted without delay, not only to prevent future seabird losses in the 2025 breeding season, but also to protect the many waterbird species that winter in Ireland and are too at serious risk from HPAI. Despite two cases of avian flu in Little Terns in Ireland, the species escaped largely unscathed and almost all colonies reported increased nesting numbers in 2024. We will report on the Little Tern breeding season in the coming weeks.The full study entitled "A case study of the 2023 highly pathogenic avian influenza (HPAI) outbreak in tern (Sternidae) colonies on the east coast of the Republic of Ireland" was published in the journal Bird Study and can be accessed here.
The Rockabill Tern conservation project is a joint project between the National Parks & Wildlife Service and BirdWatch Ireland. https://www.npws.ie/
The Dublin Port Tern Conservation project is funded by Dublin Port Company as part of BirdWatch Ireland's 'Dublin Bay Birds Project'. https://www.dublinport.ie/
The Tern conservation project at Lady's Island Lake is a National Parks & Wildlife Service project, delivered by BirdWatch Ireland after a competitive tender process. https://www.npws.ie/
