Friday, 15 August 2014

Changing of the Guard

It's all change in Dublin Bay as the tern season comes to a close and the first good numbers of waders return south from breeding grounds in colder northern climes. The first returning waders tend to be non/failed breeders, followed by successful breeding birds and juveniles. The terns have raised their chicks (or failed, to as may be the case), and are now preparing to migrate south in the coming weeks.

It's been a reasonably good year for the Dublin Port terns with more Common and Arctic Tern nests than in 2013. Mild conditions and few extreme weather events will have helped their cause this year. Predation (probably by corvids) had some negative impact in the early season, but seemed to resolve when the full complement of adult Common Terns returned to breed and protect the colony. A nest count, on June 18th, gave 487 and 96 Common and Arctics, respectively. On the 11th June last year, there were 418 and 25 Common and Arctic tern nests.  

Common Tern chicks with some new jewelry Helen Boland

The terns will now begin to gather en masse in large mixed flocks across Dublin Bay in the coming weeks, with numbers peaking in mid-September. They will then trickle south, where many will winter along the West African coast.

On any given evening in September you will be able to witness up the terns roosting on Sandymount Strand. These species include Common Terns in very high numbers, good numbers of Arctic and Roseate Terns and handfuls of Sandwich Terns. You might also be lucky enough to to bag yourself a sighting of a Black Tern, which are annual visitors to Dublin Bay, en route from breeding colonies on the Continent. Our Little Terns leave directly after breeding and are rare in post-breeding flocks.

Post-breeding flock on Sandymount Strand Dick Coombes

As the tern numbers build, they are joined by waders that have bred further afield, and also by some scarcer visitors. Wood Sandpipers, Little Stints and Little Ringed Plovers are a few examples.

Our common wintering wader species will now begin to grow in number with flocks of Redshank, Oystercatcher and Bar-tailed Godwits getting larger by the day. Many of these birds will spend the winter here with a host of other waders, waterfowl and gulls. One such bird, Oystercatcher "BU," has already made his way home for the winter after being seen in Lossiemouth Estuary, Moray, NE Scotland on July 17th and again in Dublin at Merrion Gates Spit on July 30th.

Home to roost - "BU"s journey from Scotland

As always keep an eye out for colour ringed birds and we would be delighted to get your sightings reported. If you read any rings do report them to us here.