IJmuiden Lesser Black-backed Gulls fitted with GPS-loggers – update 12 August 2019

An update on how our Lesser Black-backed Gulls that are fitted with a GPS logger have been doing during the first two weeks of August.

Click the images for a larger view.

Location: IJmuiden Forteiland, the Netherlands.


Many of the juveniles are still staying close to the colony and don’t venture out further away than the nearby beaches. A small reservoir just opposite the north side of the colony and a lake just south of it is also very popular.

When present in the colony, they visit the territory where they were born (mostly to be fed by their parents) and spend the rest of the time roaming around the edges of the colony.

Two of the more adventurous juveniles have already made some trips far outside the region and have been spending a night away from the colony.

The largest juvenile, Green YCZT/Logger #5953, has been spending a night out at sea, has flown north to Alkmaar, and went almost to the very tip of North Holland to Julianadorp:

It has also flown out to the North Sea, some 18 kilometers away from the colony:

YCZT when I came across it on the beach at Velsen-Noord on August 3:

Green YCZP/Logger #5943 has been spending a night at Rotterdam Europoort, but flew back to the colony again the next day.


The adults have been very consistent in their trips to the west out on the North Sea and to the east to the cities of Amsterdam, Haarlem, and Hoofddorp. It is surprising how relatively small the area is in which they operate.

YBJC is a nice example to show here. It visits the same location in Amsterdam almost on a daily basis but also fourages out on the North Sea. Together with its partner it has 3 juveniles to feed (2 of them also fitted with a logger).

During the storm that we had on Friday 9 August, and especially Saturday 10 August, a very strong wind was blowing from the south-west (7-8Bft). Apparently this made fouraging conditions out on sea impossible because YBJC only made trips to Amsterdam.

Compare a regular set of tracks from YBJC (top) with those during the storm (bottom):

Odd locations

An odd location that showed up recently was visited by YBBJ/Logger #5584 and YAVL/Logger #5963: the runways of Amsterdam Schiphol Airport. The fields around the airport were being worked on and apparently the airport itself was quiet enough for them to rest on the runways for a little while.

Disappearing adults

Of some adults we are not receiving any data anymore which means they are not returning to the colony. It is very likely that they have already started their migration towards the wintering grounds. The logger will continue to store their data until the next time we can download it, probably not until they return to the colony next year.

Until then we are dependent on visual sightings.

Once such sighting was reported to us from Shawell in Leicestershire in the UK. Carl Baggott observed YAUT on 3 August, only 4 days after the last time data from the logger was received. A very valuable sighting for our project!

Photo courtesey of Carl Baggott. Visit his website Bag a wild one….

About the project

(Source: http://www.uva-bits.nl/project/daily-movements-of-gulls-from-forteiland-ijmuiden/)

The tracking study is part of an ongoing collaboration between the University of Amsterdam UvA (Dr. Judy Shamoun-Baranes) and the Royal Netherlands Institute for Sea Research NIOZ (Dr. Kees Camphuysen).

The study is being conducted within the project “Interactions between birds and offshore wind farms: drivers, consequences and tools for mitigation” funded by NWO Applied and Engineering Sciences Open Technology Programme, Rijkswaterstaat and Gemini windpark.

The tracking study will provide complementary information on the movement patterns of gulls breeding along the North Sea coast, with similar objectives to the studies conducted on Texel and Schiermonnikoog.

The main aim is to identify intrinsic and external drivers of movement from fine scale flight behaviour to seasonal migrations. While adult gulls from other colonies have been tracked since 2008, little is still known about the daily movements and flight behaviour of juveniles and how this differs from adults.

This study will contribute to our knowledge on how juvenile birds develop their foraging and migration strategies and how their flight behaviour differs from adults.


If you come across any of our gulls from the IJmuiden Forteiland project, please let us know.

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