A week reading ringed gulls at Blaringhem landfill, France – October 2016

In the week of 24 – 28 October 2016, fellow birder and gull enthusiast Jacob and I visited the landfill of Blaringhem, France, a well known wintering location for Herring Gulls including those from many Dutch colonies.

We were hoping to come across many gulls (both ringed and unringed) and we were not to be disappointed.

In this blog post I would like to give an impression of what a day reading ringed gulls at such a location involves. In later posts I will focus more on the individual gulls that we encountered.

A big thank you

Before I start though I want to give a big thank you to Eric and Marc from the Research Institute for Nature and Forest (INBO) in Belgium for requesting the permit for us to access the landfill, to Benoît and all other management of Baudelet Environment for granting the permit and for allowing us full access to the site, to the personnel of Baudelet for their hospitality, and to Roland-Jan for his valuable assistance.

Their help has made this a very successful trip with many valuable sightings of many ringed gulls. We thoroughly enjoyed it and would love to visit the site more frequently.

The arrival of the gulls

So what does a day in the life of a gull wintering at Blaringhem look like?

They spend most of their day at the landfill site, feeding one or more times on the waste dump itself while resting in large groups (away from the dump but still on site) in-between feeding sessions.

During darkness they roost in separate groups in many of the fields that surround the landfill.

At sunrise they can be seen arriving at the site in small groups from the South and West. First they gather at one of the resting locations on site away from the dump itself, but they soon move in small groups (at high speed) to the dump where they circle to check out the situation before landing to join the feeding frenzy that is already taking place.

I was able to capture this process on video:

Within a short amount of time, the group grows into enormous numbers. Our estimation was that during the day, about 25,000 gulls visit the site.

Seeing so many gulls was quite overwhelming at times, you simply did not know where to look.

Here’s a panorama image of the site, click for a larger size:

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It got even more impressive when the gulls got spooked and all took to the air at once:

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The challenge

During the week, we were able to read about 100 ringed gulls a day. Out of a daily total of 25,000 gulls present, that is less than half a percent…

The phrases ‘needle and haystack’ and ‘forest and trees’ regularly came to mind.

So how did we find them? Simply by constantly scanning the gulls using our telescopes, hour after hour.

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The main challenge was scanning the group on the waste dump itself. Once a ringed gull was found, the challenge was to get a long enough view of it to not only read the code but to also record ring color, inscription color, reading direction and position (including that of the metal ring). Oh, and not to forget determining the species and age of the gull of course.

This requires a lot of experience with gulls in general and ringed gulls in particular including knowledge of the colour ring projects in Europe that exist for gulls. Being able to know what code and color combinations to expect and not to expect is very valuable in the field.

Of course, we were not able to read all the rings that we saw. Some birds only showed themself briefly and disappeared behind other gulls or behind one of the many hills on the waste dump, while at other times the gull flew up as soon as we got it in our scope. Such is the life of a ring reader at these locations.

The following image has got one ringed gull in it. Can you see it?

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And even when getting a good view of the ring, that doesn’t mean it can be read. Especially on a dusty location such as a landfill, rings easily get dirty:

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Some statistics

So how did we get on? Well, we were quite happy with the results:

Total number of ringed gulls read: 252
Total number of observations: 503

Rings by country:

  • Netherlands: 111
  • Belgium: 103
  • UK: 22
  • Poland: 4
  • France: 5
  • Germany: 4
  • Norway: 2

Rings by species:

  • Herring Gull: 240
  • Caspian Gull: 6
  • Lesser Black-backed Gull: 5
  • Hybrid Herring Gull x Yellow-legged Gull: 1

Notable species that were absent and/or unringed (from a Dutch ring-reading perspective):

  • Black-headed Gulls. Some 100 individuals were present each day. Many groups could be seen foraging on the fields surrounding the landfill though.
  • Common Gulls: only one 3rd-calendar year was seen briefly.
  • Great Black-backed Gulls: Only two 1st-calendar years were seen.
  • Lesser Black-backed Gulls: About 100 or so were present each day, but few ringed individuals were seen. Apparently they use a different landfill were they are in the majority whereas Blaringhem is very much a landfill for Herring Gulls.

So all in all our trip was a great result and we were able to put many ringed gulls back on the map for their respective researchers.

I will show examples of some of these gulls in upcoming posts.

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