Tuesday, 8 September 2015

Beach Party!

Autumn is upon us, but you can still catch the last beach party of the year.

Each year we observe the coming and going of autumn migration. Amid the current migrants passing along the east coast are good numbers of sea terns. These terns gather to roost as dusk approaches on the Dublin coast, and Sandymount Strand is a favorite spot, attracting thousands of birds each evening. This gathering starts when the breeding season is over, and the spectacle of thousands of roosting terns can be seen from mid-August until mid-September. These flocks made up of a species mix, gathered together as they share a migration route to Africa and beyond. Numbers will have nose-dived by mid-September, and you’ll be lucky to see a tern in Dublin after that.

Sandymount Strand awaits the arrival
of the terns 
Jen Lynch

So far this year we observed a peak of 4,200 terns. The group is made up of a number of different species, the vast majority of which are Common Terns. The remainder is made up of Arctic and Roseate Terns, and, to a much lesser extent, Sandwich Terns.

Sandwich Tern Fishing Dick Coombes

The presence of Rockabill-ringed Roseate Terns, as well as Dublin Port-ringed Arctic and Common Terns, proves the local provenience of individuals within the group. But the Sandwich Terns show that it’s not just locally breeding terns that join the roost. The nearest Sandwich Tern colonies are Wexford and Down, which tells us that birds are coming to Dublin to the roost from further afield. More interestingly, we see Black Terns with these birds on an almost annual basis. Black Terns belong to the "marsh terns" group, as opposed to the “sea terns” mentioned above. They breed on the freshwater marshlands of Holland, Poland and further east.

The fact that these birds are attracted from so far afield shows how important Dublin Bay and Sandymount Strand is for these birds, as they undertake their epic migrations to the west African coast (and far beyond for the Arctics). A record number of 51 Black Terns was observed by local birders in the flock at Sandymount on the 23rd of August and, across the Liffey, on Dollymount Strand, a White-winged Black Tern was seen. 

Ringed Roseate Tern Dick Coombes

It’s wonderful to be able to watch this migration in action, and great that’s this spectacle happens right on Dublin’s doorstep! It is a very short-lived event, though, and can only be seen between mid-August and mid-September. So grab your jacket and binoculars and get over to the coast before these graceful little creatures leave our shores for another year.

BirdWatch Ireland members enjoying the spectacle Jen Lynch

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