Group effort: ring reading during sand suppletion activities at Scheveningen – 2015

Over the last 12 to 18 months the dunes and sandy beaches at various points along the Dutch coast line have been reinforced by depositing large amounts of sand.

In the months of January and February 2015, such sand suppletion activities took place at the beach of Scheveningen, the Hague and as ever, the rich sea food that was brought along with the sand attracted large numbers of gulls, many of which were ringed.

scheveningen-pano-20150123

Scheveningen-20150215

scheveningen-20150123-2

Combined effort

The large number of gulls also brought together a group of gull enthousiasts who — in a unique effort — decided to share their observations to get an insight into the number and origin of the ringed gulls that were observed during these activities.

This article summarizes those observations.

Time period

The sand suppletion activities at Scheveningen took place from 19 January until 28 February 2015.

The totals

First of all, some totals:

Observers

Number of observers that participated 12

In alphabetical order: August Šimurina-van Rijn, Cornelis Fokker, Gerard Visser, Gerjon Gelling, Johan van ‘t Bosch, Laurens van der Wind, Leo Snellink, Maarten van Kleinwee, Rinse van der Vliet, Rob Hoeben, en Vincent van der Spek.

Species

The following types of gull were observed (ringed and un-ringed):

Herring Gull Very high numbers
Black-headed Gull Very high numbers
Common Gull High numbers
Great Black-backed Gull Low numbers
Caspian Gull Low numbers
Yellow-legged Gull Low numbers
Scandinavian Herring Gull Low numbers
Lesser Black-backed Gull Very low numbers
Iceland Gull 2 individuals
Glaucous Gull 1 indidvidual
Mediterranean Gull 1 indidvidual

ridibundus-20150205-2

On some days, a few thousand Black-headed Gulls were present.

Ringed gulls

Number of ringed gulls observed 330
Herring Gulls 223
Black-headed Gulls 73
Great Black-backed Gull 22
Caspian Gull 8
Lesser Black-backed Gull * 3
Presumed hybrid Herring Gull x Caspian Gull 1

* Lesser Black-backed Gulls breed in the Netherlands but migrate to southern Europe and Africa during the winter. Especially at the end of the sand suppletion activities, the first individuals just started to return.

Countries

The 330 individuals were split over the following countries in which they were ringed:

Netherlands 241
Norway 25
Germany 21
Denmark 13
Poland 12
Great Britain 9
Belgium 4
Lithuania 2
Russia 1
Czech Republic 1
Belarus 1

Ages

Adult 158
Sub-adult 144

Scheveningen-20150215-2

Even though the observers had the impression that most of the gulls present were sub-adults, the split across the ringed individuals is almost 50-50 and in favour of the adults.

Dutch projects

Location Ringer Species Ringed Gulls
Delta region
(Port of Rotterdam, Moerdijk,
Vlissingen)
Roland-Jan Buijs Herring Gulls
Lesser Black-backed Gulls
157
Various (but mostly The Hague) Frank Majoor Black-headed Gulls 52
Texel Kees Camphuysen Herring Gulls 20
IJmuiden Kees Camphuysen Herring Gulls 5
Rotterdam / The Hague Norman van Swelm Herring Gulls 3

Caspian Gulls

Ringin location
Age Total
Poland 3CY 2
Poland 4CY 2
Poland 5CY 1
Poland Unknown 1
The Netherlands 2CY 1
Belarus 2CY 1

Discussion

Observing ringed gulls over a set period of time at a set location is a great way to get a sense of the dynamics of that group. We were not surprised to see some individual gulls on a regular basis (sometimes daily) while other individuals were seen only once. Some gulls were also seen in other parts of the region while the activities still took place.

Even though the sand suppletion activities seem to present an almost guaranteed source of food, competition among gulls is high and it also takes skill to pick out small bits of food from a fast flowing band of water.

In contrast, some ringed gulls were expected but not seen, especially Black-headed Gulls. These are ringed at locations close to Scheveningen (Zoetermeer and Leiden), but much fewer of those were seen than was expected. Apparently the attraction of a sand supplietion was not enough to lure them away from their regular wintering locations.

What also surprised us where the low number of second-calendar year Black-headed Gulls.

All in all, the types of species and the numbers in which they appeared is very typical of what can be seen along the Dutch coast at that time of year whenever there is an abundance of food on the beach, whether it is deposited by high winds or artifically such as by sand suppletion activities.

Thank you to all observers

It has been a very interesting excercise to share all observations with a group of dedicated gull enthousiasts and ring readers. Hopefully this will stimulate us to repeat this process at future events to get a better insight at what takes place during such activites.

For now, many thanks to everyone involved!

Advertisements

2 thoughts on “Group effort: ring reading during sand suppletion activities at Scheveningen – 2015

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s