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. 

Don't mind Evelyn Cusack…

It’s officially autumn…the breeding season, and therefore the summer, is over.

OK, this may not be strictly true, but it may make you think twice about the way that we define the seasons. The reason I say this is because for some waders, the breeding season is already at an end, and northern breeders are starting to trickle in to our wetlands once again. Failed breeders start to arrive on our shores from as early as late June, and as July progresses this passage of waders will increase.

With that in mind, I want to mention a colour-ringing project that is hoping to get to grips with the migration ecology and wintering areas of the Scottish breeding population of Greenshank. The researchers are very keen to get any records they can of their Greenshanks passing through or wintering in Ireland, and these movements are already likely to have begun. So, please keep an eye out for colour-ringed Greenshanks if you are out and about. Please send details (date, location, etc.) and any photographs to Brian Etheridge (brian@milvus.myzen.co.uk).

And if you happen to come across some of our colour-ringed Oystercatchers on your travels, all the better! The latest reports we have suggest that as many as 18 colour-ringed Oycs have summered in Dublin Bay. So get out there - there really is no better weather for ring-reading!

First Tern chicks hatch at Dublin Port

Our second monitoring visit to the Dublin Port Tern colony showed that things are progressing well. On a warm sunny day in the first week of July, we ringed the majority of the ringable Common and Arctic Tern chicks.

So why ring these chicks? Well, it allows us to find out how many young birds leave the nest each year and survive to become adults, how long these adults live and where they breed in subsequent years. To learn more about ringing click here.

As we approached platform, we estimated the flock size to be 285 adult Common Terns (but bear in mind that a good deal of the colony will have been off foraging). On climbing up onto the platform, we could immediately see that things were going really well - there were good numbers of chicks and quite a few already on the run - it only takes a couple of days before these guys are mobile. We ringed 262 Common  and 13 Acrtic Tern chicks.

Arctic Tern nestling. Niall Tierney

Thankfully, there was no evidence of the egg predation that we reported in the last post. Now that the colony is in full swing, let’s hope that the terns can drive off any intruders. A passing Great Black-backed Gull got the “tern treatment” while we were ringing, and it made as fast an escape as possible!

Tern eggs show remarkable variability, but these erythristic Arctic Tern eggs were interesting.

Erythristic Arctic Tern eggs. Niall Tierney

Other bird sightings included Cormorants, Black Guillemots, Common Sandpipers and three well grown Kestrel nestlings in ‘window-nest’ at old Pigeon House power station. A Peregrine was heard calling briefly as well.

Breeding terns update

The main tern nest census was carried out on a fine day last week, and showed good increases in the number of nests and clutch sizes since our last visit.

As we rowed out to the platform, we could see that something was distressing the terns – they were repeatedly diving at an unseen intruder towards the eastern end of the platform – and we immediately suspected a pillaging corvid. We climbed the ladder to the platform and carefully picked our way (tern eggs are almost invisible on the shingle substrate) to the eastern end to find a Kittiwake spread-eagled across one of the nests. A quick examination revealed that the bird was very freshly dead, but showed no signs of external injury. Whatever the cause of death, this bird picked a less than peaceful refuge for its final moments... 

Common Tern nest in Dublin Port. Niall Tierney. 

Anyway, we promptly got back to the job in hand – the nest census. This is simply a count of the number of nests and the number of eggs per nest. This, along with the estimation of the number of adult birds present, allows us to see how the colony is faring from year to year. On the main platform, 418 Common Tern nests were recorded, with clutch sizes ranging between 1 and 4. There were 25 Arctic Tern nests, with clutch sizes of 1-2. There was an increase in the number of cached depredated egg shells, indicating that the (still unidentified) avian predator had been on the platform since the earlier visit (see previous post).

Two Arctic Tern nests in Dublin Port. Niall Tierney.

Once the census was complete, we quickly vacated the platform to allow the adults to resume incubation. Peak hatching is expected to be around the turn of the month. We’ll check back in on the colony again in the coming weeks to monitor breeding success and will post another update then. 

Breeding Terns in Dublin Port

Dublin Port has been home to a colony of breeding terns since at least 1949, and in recent years, has supported 550 and 55 pairs of Common and Arctic Terns, respectively. The monitoring programme that was started by the late Oscar Merne in 1995 will be continued by BirdWatch Ireland this year, and in subsequent years.

Tern platform in Dublin Port. Richard Nairn

Although the cold spring has resulted in delayed commencement of breeding for lots of birds, the Common and Arctic Terns in Dublin Port are now nesting. Last week’s colony census recorded 263 Common Tern and 8 Arctic Tern nests. Worryingly, a cache of at least 23 tern egg shells was found on one of the platforms, with the culprit most likely a corvid. 

Depredated tern eggs cached on the platform. Richard Nairn

As the colony reaches it full strength, it’s likely that the full complement of terns will be sufficient to drive off any intruders. As someone who has ringed in tern colonies, I can tell you that hundreds of angry terns have no trouble making their feelings known...

The joys of tern fieldwork!

Summering waders

Sandymount strand was chock-a-block with joggers, walkers and dogs on Sunday morning, but they weren't the only ones taking advantage of what Sandymount Strand has to offer. As soon as I pulled up, I noticed a flock of ‘smalls,’ (i.e. unidentified Dunlin-sized waders) pinging around between the joggers and dogs. A glimpse of some black bellies allowed me to confirm that they were mostly smart-looking, summer plumaged Dunlin, but there were some Ringed Plover tagging along too. A quick scan with the scope through the heat haze produced 109 Oystercatchers distributed in several aggregations and a flock of 154 Bar-tailed Godwits on the tide line further south, towards Booterstown Station.

To be honest, I was surprised to see so many waders still hanging around on the beach. I don’t usually give too much thought to waders outside the September to March I-WeBS season. I suppose it just goes to show how important year-round counts are at a site like Dublin Bay.

Sunny Sandymount Strand

The ring-reading conditions were perfect: pleasant temperature, good sunshine and a backing track of Swallows and Common Terns chattering and squabbling overhead. I managed to read twelve rings, but there were 5 or 6 that I just couldn't get....something ‘J’... or was that something ‘I’... No, definitely an ‘L’...but what’s the first letter? Get out of that puddle and let me see it!

Thanks again to those of you who have been diligently sending in ring re-sightings. We’re slowly putting this story together, but new ring readers are always welcome to contribute to this worthwhile research. No need for flasks or hats or gloves - just grab the scope and the notebook and get out there! 

Arctic Terns – extraordinary migrants

As you know, we have put colour rings on a number of Oystercatchers to allow them to tell us a story about their movements around Dublin Bay and beyond, and we intend to do some hi-tech tracking work in the coming years too. Who knows what story this work will tell?

...But if birds could actually tell stories, what would they say?