French Wireless gull (Larus cyborgus) @ the Eirol landfill, Portugal (November 3, 2015)

Peregrine Falcon versus Black-headed Gulls at the Eirol landfill

There currently seems to be a Peregrine Falcon Falco peregrinus residing at the Eirol landfill. It was observed yesterday, November 17 2014, while it hunted repeatedly on the smaller birds present at the site. In search for prey it was flying through the thousands of gulls above the landfill.








It’s a 1st winter male, which appears to have a remarkably dark plumage. The head and breast of this bird are extremely dark, making me unsure about what subspecies it would belong to.






Its favorite perch is a dead branch in the top of a Eucalyptus tree, overlooking a ditch with fresh water that attracts many of the gulls and other birds present at the site, including Black-headed Gulls Chroicocephalus ridibundus. And those Black-headed Gulls are of interest to the falcon. Throughout the day we noticed it making several unsuccessful attempts to catch one. We also found some remains of a Black-headed Gull that recently had been eaten by a peregrine.




In the morning, before we realized there was a peregrine present at the site, we already noticed there were very few Black-headed Gulls present. During the past few weeks their numbers had been increasing, as many northern wintering birds were arriving. Yesterday we counted only 75 Black-headed Gulls. The number of Black-headed Gulls on previous visits is shown in the table below. At the moment many of those Black-headed gulls probably realize it’s smarter to stay away from Eirol.




Thanks to Pedro Moreira for the close up photos of the falcon!

A special guest at the landfill

On October 4th 2014, Paul Veron (http://guernseygulls.blogspot.pt/) joined Pedro Moreira and me on a ring-reading trip to the landfill of Eirol. Due to the surprisingly large number of gulls present at the site (15 – 30.000) a record amount of rings were read. More about this event can be found on Paul’s blog in some time from now. Among all these birds was a single Herring Gull Larus argentatus.

Gull-rings around Aveiro, Portugal (September 11, 2014)

Gulls arriving at the Eirol landfill. We managed to read 64 rings between 07:35 - 13:15, all on Lesser Black-backed Gulls. Roughly 6000 gulls were present at the site. Many birds left the site early, presumably due to the lack of garbage being delivered to the open dump.






Xavega fishery at Praia da Vagueira. 5 rings were read between 14:00 -15:15, all on Lesser Black-backed Gulls. 150 gulls were present, primarily LBBG.




Blue 23 at Praia da Vagueira, ringed in the southwest of The Netherlands.




Red VB1.T at Praia da Vagueira. Ringed at a landfill site in Greater London, UK.




Reading rings at Porto de Pesca, Gafanha da Nazaré. 8 rings were read there, 5 on LBBG, 3 on Yellow-legged Gulls. Gulls not counted.




White HC, from the southwest of The Netherlands (photo: Pedro Moreira).




Subadult Yellow-legged Gull R:R8T; ringed in France (photo: Pedro Moreira).

Gulls at the Eirol landfill, Aveiro (Portugal): March 11, 2014

On March 11 Pedro Moreira and I visited the Eirol landfill again. We searched for rings between 7:00 and around 14:30. The weather was great, no or hardly any clouds and a lot of sun, probably a bit too much for the time of the year. There were fewer gulls present; about 9.000 Lesser Black-backed Gulls, 1500 Black-headed Gulls, 40 Yellow-legged Gulls and two Mediterranean Gulls. Highlight of the day was a first observation of a Common Gull for the site. We managed to read the rings of 35 Lesser black-backed Gulls and 2 Black-headed Gulls.

 Common Gull Larus canus

Procambarus clarkii is a freshwater crayfish species, native to the Southeastern United States, but found also on other continents, where it is often an invasive species. In this area these tasty snacks are taken by White Storks and Lesser Black-backed Gulls in marshy areas. They can currently be found around the landfill in large numbers in the shape of regurgitations that were dropped there primarily by the gulls, I suspect. The number of storks is currently very low; we counted only one during this stay, though it might be possible that more storks visit the site at later times of the day. On the other hand, the recent floodings in the area might be very beneficial for the storks (as well as for Procambarus clarkii?) so there maybe is no need for them to come to the landfill. I hope that the people involved in this study: http://www.bto.org/science/migration/tracking-studies/stork-tracking/about are aware of relatively recent and increasing occurrence of Procambarus clarkii in the White Stork’s wintering areas.

Lost racing pigeon Columba livia forma domestica, with a ring we did not manage to read.

 Two photos of the first recorded Water pipit Anthus spinoletta for the Eirol landfill (thanks to Pedro).

Gullrings at the Eirol landfill, Aveiro (Portugal): March 3, 2014

Today Pedro Moreiro and I visited the Eirol landfill. We searched for rings between 7:15 and 14:15. There were a few short showers spread out over this period, but most of the time it stayed dry. It was also rather windy. There were fewer gulls present than during our previous visit; about 19.000 Lesser Black-backed Gulls, 2000 Black-headed Gulls, 150 Yellow-legged Gulls, one Greater Black-backed Gull and one Mediterranean Gull. We counted 15 Black Kites, which regularly flushed the gulls and by the time of our departure had pretty much claimed the pit, making it difficult to read anymore rings. 41 rings were read. Some of today’s photos:

Adult Black-headed Gull Chroicocephalus ridibundus, from the UK.

Adult Mediterranean Gull Larus melanocephalus

Immature Lesser Black-backed Gull Larus fuscus, from Scotland.

Adult Lesser Black-backed Gull Larus fuscus, from The Netherlands.

 Immature Greater Black-backed Gull Larus marinus.

Eirol landfill, February 19, 2013: the last of this winter's visits, and the terror birds are back!

This entry is about my most recent visit to the Eirol landfill (February 19), during which I was hoping to gain a good final number of color-ring sightings, as it would be my last visit to the site for this winter. There were still plenty of gulls present (about 16.000 Lesser Black-backed gulls Larus fuscus), but as mentioned before the ring-reading conditions there are not as good as they once were at Taboeira: rings get dirty more easily, birds are harder to observe from the right angles, and many of their roost sites are out of sight for me.
This time things were a bit different, primarily because the first Black Kites Milvus migrans have returned from their wintering quarters in Africa. These kites continuously flushed the gulls from their hidden roost sites, forcing them to perch at different locations, allowing me to see their rings more easily. A total of 58 color-rings were read and these had been applied on Lesser Black-backed Gulls in Britain (excl. Guernsey) (19), Guernsey (18), The Netherlands (10), Norway (3), Germany (2), France (2), Denmark (2) and Belgium (2).
British birds seemed to be dominating the site. I noticed a similar situation taking place a year ago at Taboeira, when during the second half of February the number of British gulls appeared to increase while those originating from other NW European countries decreased. This will undoubtedly have something to do with the gulls’ spring migration movements, as the majority of the birds will already be on their way to their breeding grounds further to the north. I will be following some of them in a few weeks from now.

 

The first of three Black Kites that showed up during the day…

…and the mass-hysteria among the gulls that always seems to follow the appearance of a kite.

These kites were more than capable of expelling the gulls from the large mound of sand that is located at the east side of the landfill. They’re more than welcome to do so, as this allowed me to observe a lot more gulls in places where their rings could actually be read...

I.e. on the roads right next to the observer.

And this time the birds roosting in the pit were too afraid to kneel down, so there were plenty of legs to scope out.

Then of course it’s important that the ring itself allows proper reading and its inscription is not either too worn or too dirty. I'm not sure where this one came from, but it's probably British.

A new one for me; Chris Perrins’ GREEN TA, with a tiny and dirty WHITE inscription (vertical inscription; top – bottom). Also very British.

Philippe Dubois’ RED 974K with a WHITE inscription, from France. Well, initially there was a white inscription visible on this ring; nowadays you'll have to get very close to this bird for a proper reading.

RED TB5.T, BLACK inscription, a bird from Paul Roper & the North Thames Gull Group, is showing an unmarked companion how to drink dewdrops in the early morning.

 David Sowter’s BLACK WC3W, YELLOW inscription; very condensed inscription, but in the end Britannia ruled the waves at the landfill.

Apart from color-ring reading I spent some time inspecting gull carcasses again. Unfortunately for Mike Marsh the only bird from him that got reported from Eirol was this LBBG RED AZ.AC, WHITE inscription (metal BTO GR20352). It was ringed as a pullus on the 4th of July 2010, on Havergate Island, Orford, Suffolk. Afterwards it got reported regularly by others in Faro (Portugal), once from Torreira, and a few times by me from the former Taboeira landfill. An additional two British ‘metal only’ LBBG’s were found. A broken wing had been the initial cause of death for all of these three gulls.

Besides the resightings, the overall birding turned out to be very good again. It all started off with an adult male Marsh Harrier Circus aeruginosus patrolling the site for a while. It caused some disturbance among the gulls, but nowhere near as much as the first kite that would show up an hour later.

A single Mediterranean Gull Ichthyaetus melanocephalus among Black-headed Gulls Chroicocephalus ridibundus and one Lesser Black-backed Gull.

A Pied Wagtail Motacilla alba yarrellii, which I consider to be part of the British invasion of the landfill as well.

I also ran into this strange looking bird, presumably a female Herring Gull Larus argentatus. Considering the number of gulls I see on a regular basis, the number of rarities that get reported by me (compared to those reported by my ‘gull friends’ from the Iberian Peninsula) seems to be rather low. I suspect that I spent too much time scoping out gull legs instead of gulls themselves, so I probably miss out on a lot of fun. Still, Herring Gulls are rare in this part of the world, but in a few weeks from now I’ll have plenty of them flying around my head and they will appear normal again.