What’s in a name?

Why are our chocolate brown-headed gulls called Black-headed Gulls?

Since arriving from Spain to work on this project, I’ve been puzzled by this! At home, we call them Gaviota Reidora, or laughing gulls, due to their calls...which makes a bit more sense, doesn’t it?

Black-headed Gull, breeding plumage. Ronnie Martin

Anyway, since we started the monitoring programme in Dublin Bay, we’ve counted lots and lots of them. We had a peak count of 5,917 on the low tide count on the 19^th of August. We haven’t managed to get any colour-rings just yet, but they are certainly worth looking out for. In the autumn of 2011, a colour-ringed Black-headed Gull was spotted in Booterstown. It turns out that this guy also had his colour ring read Poland in May 2010 and had flown 1,608 km to spend the winter in Dublin.

The re-sighting location and the sighting site in Poland (blue)

As it happens, the Irish Wetland Bird Survey (I-WeBS), which monitors wintering waterbirds throughout the country, is initiating a Gull Roost Survey this winter in order to get a handle on how our winter gulls are faring. If you happen to know of any places where gulls congregate at night roosts, it’d be great if you could let the I-WeBS Office at BirdWatch Ireland know. 

Black-headed Gull in winter plumage. Shay Connolly

Meet AJ - the record breaker

AJ holds project records for the longest distance travelled, the first Norwegian re-sighting, the second Norwegian re-sighting and is the (almost) record holder for the shortest bill at the time of ringing! What a bird!

Long distance record holder - AJ. Arnt Kvinnesland

AJ was re-sighted and photographed at Stavasanden, Karmøy, Rogaland, Norway on the 2^nd of April and on the 3^rd August 2013.

The re-sighting location for AJ (red) and the original ringing site (green)

AJ’s bill measured just 64 mm at the time of ringing and was beaten only by AZ (with a bill tip to feathers measurement of 63 mm). DJ, who turned up in Orkney on the 1^st May, and who happens to be the previous long distance record holder, had a bill length of 90 mm at the time of ringing, which was the longest of all 119 birds ringed.

Comparison in bill length between DJ and AJ. 
Colin Corse, Arnt Kvinnesland

Oystercatcher bill length is a result of their foraging strategies. Some opt to smash open their preferred prey – cockles and muscles – by hammering at them and blunting their bills, while others take a different approach and prise them open. Their bills are constantly growing (like our finger nails), so it’s possible for them to change in length depending on the prey they are exploiting at a particular time.

Returning Waders

This project involves year-round monitoring of Dublin Bay and the waterbirds it supports. A team of ornithologists will be surveying the area at various tidal stages and times of the day (including at night!) to chart waterbird distribution, abundance and behaviour throughout the bay. This information will allow us to build up a comprehensive representation of how the birds are using the bay for roosting and foraging (click here for more info on this) and will allow us define the most important areas.

Greenshank (right) with Redshank  John Fox 

Our first counts took place last month, and we notched up 24 different waterbird species. As expected, numbers were still low, as the majority of the northern breeders have yet to arrive. We had good numbers of Greenshank, most presumably on passage, but we didn’t manage to see any colour rings (click here for more info on colour-ringed Greenshank). Curlew, Redshank and Oystercatcher were present in decent numbers, and we had a few Whimbrel too.

Curlew Dick Coombes

It was great to be watching Bar-tailed Godwits in their “tomato soup” coloured summer plumage and Black-headed Gulls with their chocolate brown hoods while listening to House Martins and Swallows chattering overhead on their aerial pursuits. But it won’t be too long now before the summer plumage and the hirundine backing track fades, and we’re left with drab winter plumage and cold hands…

New Tern raft

You may be wondering about the new structure in the Tolka Estuary? 

In May this year, a raft was moored in the Tolka Estuary by the Dublin Port Company, with welcome assistance from members of the Clontarf Yacht and Boat Club.

Dublin Port Company’s tern raft near Clontarf. Richard Nairn

This large steel pontoon, last used for the Tall Ships’ visit to Dublin Port, has been specially adapted for breeding terns, by adding timber walls and a gravel layer, to mimic a single beach. 

Common Terns carrying fish to chicks on the tern raft. John Fox

Up to 12 Common Terns have been recorded on the raft over the summer, with one pair successfully raising young. 

Tern chicks prepare for takeoff!

On the third monitoring visit to the Dublin Port Tern colony, most of the eggs had hatched and there was a good mix of ages, from one day old fluffies (to use the technical term!) to those almost ready to fledge.

Two fluffies and an adolescent! Niall Tierney

Most had been ringed in the previous monitoring visit and looked in great shape, and we managed to round up and ring the majority of the others. No signs of predation to report once again, which is great, especially after the devastating year they had last year when the high rainfall and unprecedented predation effectively wiped out the entire colony. Terns are long-lived and therefore have the ability to cope with terrible years like 2012, and hope to get luckier the following season. We ringed 186 Common and 19 Arctic Tern chicks, giving us a total of 450 Commons and 32 Arctics for the season. 

Arctic Tern. Dick Coombes

So what did we learn? Well, one key lesson is to always wear a hat when ringing in a tern colony (ouch!), but more importantly, ringing these chicks will allow us to learn a great deal about where these birds go, where they subsequently breed and how long they live. Who knows, we may have just ringed the future Common Tern longevity record holder!

Typical Common Tern life expectancy is about 12 years, but the maximum recorded age, according to BTO records, is 33 years and 6 days. This bird was ringed as a nestling in Northumberland on the 1st July, 1963 and it’s ring was read through a telescope in Liverpool on the 7th July 1996! 

Common Tern. Dick Coombes

Other notable bird sightings on the day included Black Guillemot, Common Sandpiper and two Sandwich Terns. The Pigeon House Kestrel nest ledge was empty and the three young were known to have fledged the previous week.

Celtic links

Ninety one of the 119 Oystercatchers that we ringed on Sandymount Strand last February have now been re-sighted at least once. The majority of these re-sightings have been from locations on Sandymount Strand itself, but there have also been several reports from some playing pitches in south Dublin and individual sightings at Bull Island, Dalkey Island and Baltray, Co. Louth.

And we’ve just heard about two birds that have been re-sighted in Scotland, providing an international context to the study. JL was re-sighted in Argyll on the 10^th April, and DJ was photographed in Orkney on the 1^st May.

Re-sighting locations for JL (green) and DJ (red).

We’re not surprised that these birds have been seen in Scotland, but these records are notable as they are our first international re-sightings. Who knows where our next international records will come from? 

DJ at St Peter's Pool, Deerness, Orkney on 1st May, 2013. Colin Corse.

Meet LV

We ringed this guy and his two siblings last week in Kilcoole, Co. Wicklow. It will be interesting to see if he turns up in Dublin Bay this winter. 

Oystercatcher "LV" foraging with parent. Niall T. Keogh

Looks like he’s getting a foraging lesson from one of his parents. Who knows, today’s lesson could be on whether he’s going to be a smasher or a splitter! It has long been thought that juvenile Oycs learn their foraging strategy from their parents, i.e. whether they gain access to mussel shells by hammering at them or by prising them open. However, it now seems that things are more flexible, and that the birds can switch between foraging approaches.