The Common Tern (An Gheabhróg)
The common tern, Sterna hirundo, is one of Ireland’s five breeding tern species that nest and breed here over the summer months.
Common Terns at Lough Carra
Although they have been recorded visiting Lough Carra regularly over the last number of years there have been no breeding pairs that have successfully fledged chicks on the lake since prior to 1940.
This is largely due to the lack of suitable nesting sites where these ground nesting birds are protected from predators. The invasive american mink has been a particular problem for ground nesting birds since it’s introduction to Ireland for fur farming in the 1950s. This is because many native birds have no natural defences against this opportunistic semi aquatic predator that can swim out to small islands where many birds would naturally nest.
The Project
Inspired by the success of the tern rafts in Lough Atalia in Galway city, where the Conservation Volunteers Galway, and ATU have been constructing and managing rafts for the last seven years, the NPWS decided to try help this amber listed bird in Lough Carra by installing a tern raft on the lake.
Funding for the raft was provided by the NPWS and two of the Mayo rangers, Brian Hughes and Sean Harrison were assisted in this project by the LCCA and a group of local volunteers, Pádraig Farrell, Nuala Irwin and Michael Kingdon.
Based on the designs for the rafts in Galway city they built a predator proof raft out of recycled plastic and perspex with a gravel base to mimic the natural nesting habitat for terns which would be on pebble shores or beaches. It also included a caller to play the calls of terns to attract terns to the raft along with some small wooden shelters to protect the terns in hot weather and from attacks by gulls.
Did it work?
The tern raft was put out in the lake in early April, attached to an anchor to hold it in place and within a few days a few common terns were spotted flying around the raft to assess it’s potential as a nesting site.
Brian Hughes explained having the tern caller on the raft to play their calls really helped bring the terns into the raft. Terns naturally prefer to nest in colonies as it can provide safety in numbers so terns are attracted to the sounds of other terns calling.
Soon after one pair of terns began nesting and they fledged three chicks in their first year breeding on Lough Carra. This is an amazing achievement as it is outlined in the book, ‘Birds of Counties Galway and Mayo’ by R.F. Ruttledge that
“Up to about 1920 large numbers nested on Loughs Carra and Mask: decrease then set in and breeding on Lough Carra had ceased prior to 1940, and a few continued to nest on Lough Mask.”
This project marks the the first confirmed record of terns breeding on the lake in over 86 years so it is incredible to have all three chicks fledge successfully and it is really important for Ireland’s common tern population.
(To put this timeline into perspective Lough Carra has waited even longer for the return of the breeding terns than Mayo has waited for the return of the Sam Maguire)
What is next?
For the three tern chicks they will spend the rest of the summer here in Ireland before they undertake their first migration down to sub-Saharan Africa for the winter. If you are visiting Lough Carra in the summer months keep an eye out for these elegant streamlined birds flying over the lake.
As for the project it will continue next year and Brian hopes that we will see more pairs of terns nesting there in 2027. If this year’s pair return again their presence on the raft should help attract other terns to hopefully establish a colony.
Further down the line this project could consist of the exciting prospect of several tern rafts on the lake to ensure that there is a sizeable breeding population present here. This will help protect the long term viability of the local tern population from avian flu.
Sources:
Common Tern – BirdWatch Ireland
https://www.bbc.com/news/uk-northern-ireland-66119781
R.F. Ruttledege (1994). Birds of Counties Galway and Mayo. Copyright of Irish Wildbird Conservancy. Dublin, Cityview Press.