Last gull rings to be read at the Eirol landfill? (February 17, 2015)

Today the landfill of Eirol got visited by Pedro Moreira and me for another day of gull ring-reading. Beforehand we got informed that certain measures were going to be taken to take care of the gull problem. These measures initiated yesterday. In about half an hour we managed to read four rings, all on Lesser Black-backed Gulls. Then a falconer made its appearance, together with two Peregrine falcons and a gas cannon.

 

Adult male Peregrine falcon.

 

Gas cannon

 

Panic
 

The first panic among the circa 4000 Lesser Black-backed Gulls and 300 Black-headed Gulls was caused by the falconer’s female Peregrine that got flown around the site for a short while. After this it was the gas cannon that made the gulls decide to abandon the site. We were later informed that the falcon had also flown away. Its gps signal indicated it already had made its way to the coast within a few minutes, probably faster than any of the gulls. In the end it was the gas cannon that made the gulls completely abandon the landfill.



Empty landfill...



Peregrine kill, but from Eirol's own falcon.


Regular blog readers will already have gotten used to the presence of a Peregrine falcon on the Eirol landfill (see previous posts). That bird already successfully reduced the number of Black-headed gulls at the site. During the past couple of weeks this now 2nd cy bird had remained faithful to the site. Today we searched for prey remains left behind by that falcon and found remains of another four Black-headed gulls. However, we did not see the bird itself. The last observation of it came from the falconer, who informed us that yesterday, after releasing his own Peregrine, our young falcon came to attack it and defend its feeding ground.

The current bird eradication program is planned to continue for two months. I suspect it will also keep out the Black kites from the landfill, which are supposed to arrive during the second half of February, and have already proven to be successful in reducing gull numbers to zero there during summer.

Eirol landfill, Portugal (January 12, 2015)

One of two adult Herring gulls Larus argentatus present at the site.




Herring gull number two.




Ringed Mediterranean gull Ichthyaetus melanocephalus, from Véron, les Prés Pendus, Yonne, FRANCE 48,07N 3,17E. One of two birds observed.




A Pied wagtail Motacilla alba yarrellii (top) and white wagtail M. a. alba (bottom).




The only signs of the young Peregrine falcon Falco peregrinus that resided at the landfill for some time (see previous posts) were 10 older remains of Black-headed Gulls Chroicocephalus ridibundus…

...and, remarkably, the remains of a 1st winter Lesser Black-backed Gull Larus fuscus. Not a common prey for a Peregrine.

Peregrine Falcon at the Eirol landfill: the story continues (December 3, 2014)

During recent visits to the landfill we were pleased to see the immature Peregrine Falcon Falco peregrinus (or hybrid?) was still around, putting some pressure on the Black-headed Gull Chroicocephalus ridibundus population. Recently, many new gulls have arrived from the north. The number of Black-headed Gulls increased to about 500 birds. Many of the new birds will have been unaware of the falcon’s presence. This will make them easy prey for the Peregrine, which is still operating from the top of the same Eucalyptus tree, aiming for the gulls that come to take a bath in the ditch below the tree. The ground around this ditch is currently littered with the remains of at least 9 Black-headed Gulls.










Among the new gulls that recently arrived at the site was this Black-headed Gull from Poland (White THPP).




The single Common Gull Larus canus were recorded on December 3, 2014.




It would be interesting to see how the Black-headed Gulls will deal with the presence of the falcon this winter. Since I’ve never visited Eirol in December there’s no data available about the number of gulls present at the site around this time. At the time the Taboeira landfill was still operational, during four visits in December 2011, I counted between 2500 and 5000 Black-headed Gulls...

Gull rings & the Yellow-legged Gull (Larus michahellis) as probable breeder in Aveiro, Portugal

Yellow-legged Gull PFFF, ringed in Spain, observed at the Porto de pesca (photo: Pedro Moreira)

 
On August 28 Pedro Moreira and I went out to search for colour-ringed gulls in the area around Aveiro, Portugal. Our day started at the Eirol landfill, where usually good numbers of gulls are present, especially now that fall migration has started. However, the number of gulls there turned out to be a bit disappointing. We made a very rough estimation of about 3500 Lesser Black-backed, 150 Yellow-legged and 20 Black-headed Gulls; similar numbers as on our visit to the site of August 21. Unfortunately, most of these birds perched on the roofs of the buildings, making it difficult to read their rings. There were moments when the whole pit remained empty from gulls. Only 35 rings were read (fewer than last time). Around noon we decided to leave the place and find out where our birds had gone to.

An empty landfill

We passed by the beaches to see if bycatch from Xavega (the traditional fishing where the catch is landed on the beach, see Paul Veron's blog entry about this event: http://guernseygulls.blogspot.pt/2014/08/the-exodus-of-lbbgs.html) was attracting them. But as the waves were too high that day (as on the previous days), there were only few gulls present, all of which were flying over the ocean. Better luck we had at ‘Porto de Pesca’, the largest fishing harbour in the area. Roughly 1500 Lesser Black-backed Gulls were present there, allowing us to read 8 rings on those. Besides these Lesser Black-backed Gulls, about 400 Yellow-legged Gulls were present in the harbour. Of these at least 5 were ringed.

Lesser Black-backed Gull 'E4', at Porto de Pesca. Ringed in the SW of the Netherlands (photo: Pedro Moreira)

 

 

 

Yellow-legged Gull N:1NC, from Spain, observed at the Porto de Pesca (photo: Pedro Moreira)

Yellow-legged Gull 1Y5 at the Porto de Pesca; note the worn and open colour-ring, about to fall off (photo: Pedro Moreira)

Some of these Yellow-legged Gulls, all adult birds, have been seen at the harbour earlier this summer. Apparently the seaport to Aveiro is attractive for this species. With many expanding breeding populations in nearby areas (i.e. Porto), it would be just a matter of time before they start nesting here (assuming that they didn’t do this already). And indeed, we found information that by now Yellow-legged Gulls nest in the harbour!

While searching for rings we noticed two immature Yellow-legged Gulls begging at two adults, which were involved in some kind of social conflict with a third adult bird. With the appearance of our car, the adults started to alarm. Both chicks were able to fly properly and could be considered fledged.

Two begging Yellow-legged Gull chicks and their presumed parents (photo: Pedro Moreira)

Of course, observations of begging but fledged gull chicks are by no means good evidence that the chicks were born in the area, as they are capable of following their parents over long distances. However, our suspicion that these were in fact local birds gets supported by the following information I received from Pedro.

The same begging Yellow-legged Gull chicks and their presumed parents (involved in social interactions with a third bird)

On August 8 Pedro visited the harbour to read rings and talked there with a fisherman, very close to the particular location. He was told “You are late! You should have come earlier to see the nest!”. Apparently there had been a nest on the dock on a rolled up rope, containing three eggs. Out of these two chicks hatched. It was the first time the fishermen had seen it there. When Pedro approached the location of the nest he got dive-bombed by an adult Yellow-legged Gull. A bit further away he saw a young juvenile (about the same in size as the ones on the photos above). Then Pedro realized he had been dive-bombed at the same location earlier in the summer, on July 17. He never saw the nest but never looked for it either. At inspection of the location on August 28 we did not find any remains of any nest, but by that time it would have been washed away by the elements. It seems probable that the two chicks we observed belonged to this nest.

It would be interesting to see how in the future the migrant and wintering population of Lesser Black-backed Gulls in this part of the world is going to deal with an increasing Yellow-legged Gull population, since competition for food between the two species can be expected. If you happen to know more about nesting gulls in or near Aveiro (and this would not be the first nesting of the Yellow-legged in the area) I would be very interested in this information.

After this encounter, we headed to the Porto de Commercial, where during the high tide a large parking place gets used by the gulls as a roost. 2000 Lesser Black-backed, 500 Yellow-legged and one Greater Black-backed Gull were present. 8 rings were read.

Part of the large gull-roost at the Porto de Commercial, Aveiro

This number of gulls however did not explain where many of the gulls had gone to (we still had the impression we were missing many). It may be possible that some of the recently arrived Lesser Black-backed Gulls found a better place at the larger fishing harbours in i.e. Leixoeis or Figueira da Foz, where the larger fishing boats arrive, which are better at dealing with the waves.

Subadult Greater Black-backed Gull Larus marinus (photo: Pedro Moreira)

Migrated to Portugal...

… and joined Pedro Moreira on a trip to the Eirol landfill to look for gull rings and some general birding. 3500 Lesser Black-backed Gulls, 100 Yellow-legged Gulls, 40 Black-headed Gulls, 1 Audouin's gull, 541 White Storks and 8 Black Kites were present. 44 rings were read, all around the legs of LBBG’s.


1st year Audouin's gull Ichthyaetus audouinii




We also visited some of the salt pans near Aveiro to look for shorebirds. By now, many Dunlins and plovers have arrived from the north.


One Dunlin stood out from the crowd: a possible partially albino or leucistic individual. Pedro also noticed the same bird at the Salinas some time earlier.

Gulls at the Eirol landfill, Portugal. February 26, 2014.

Due to other obligations and very poor weather conditions, the Eirol landfill had not been visited by me for a long while. Yesterday, there finally was a gap in the clouds. On this trip I got joined by Pedro Moreira. Pedro was particularly interested in the rarities that occasionally show up at the site, but as far as gulls went we did not record anything else then Lesser Black-backed -, Black-headed - and a few Yellow-legged gulls. There were plenty of gulls present; in particular the first two species were abundant. I was hoping to be able to visit the site before the first of this year’s Black Kites showed up, but we quickly found out that they were already there. We made a maximum count of 25 kites, which continuously flushed the gulls. According to personnel the first kites appeared around the 21st of this month. Between 7:15 and 16:45 Pedro and I managed to read 46 rings (44 LBBG and 2 BHG). This number could have been a lot higher if it weren’t for the dirt that covered many (about 40%!) of the rings, as well as for the time we spent talking with personnel of the site, and for the time we watched the impressive interactions between the gulls and the kites, making it a very nice day after all!

Here Fido, bring me the slipper.

 

Gull rings at the Eirol landfill, Portugal, September 3 2013

A waste of time at the landfill? Between 7:00 – 11:30 there were about 3250 Lesser Black-backed Gulls that visited the site. I highly suspect that the amount of exposed and delivered garbage has become a limiting factor for gull numbers. Only 23 rings were read this morning, which were applied in Guernsey (13), The Netherlands (3), Great Britain (4; excluding Guernsey), France (1), Norway (1) and Spain (1; Larus audouinii).

Larus audouinii

The only ring I could find among 550+ White Storks (bird in the middle). A dirty metal ring, placed on a tarsus.