That the end of the breeding season is now well and truly behind us is clearly shown by the GPS-data of our Lesser Black-backed Gulls from the IJmuiden Forteiland colony in the Netherlands.
Over the last couple of weeks more and more adults and juveniles have disappeared from our radar by not returning to the colony to have the data downloaded from their loggers.
On Monday 26 August, the receiving equipment was removed from the colony. At that time, only 2 tracks were captured: that of adult YCVM/logger #5441 and that of juvenile YCWF/logger #5946.
The other 9 adults and 8 juveniles had at that time already started their journey to their wintering grounds in the UK, Spain, Portugal, and northern Africa or have already arrived there.
With the receiving equipment removed we won’t be able to track the adults because they need to be near a receiver, but the juveniles are fitted with a device that also sends out SMS messages on a daily basis. On Sunday 25 August, the 9 juveniles were in the following locations:
- Netherlands: 5 (2 near the colony)
- UK: 1
- Belgium: 1
- Northern France: 1
- Portugal: 1
As you can see, they are very spread out: while some are still in or near the colony, 1 juvenile is already in Portugal. This is a pattern that we also see in adults.
The winter season
With the adults off the radar and the juveniles only sending SMS-messages, our gulls can currently not be followed online on uva-bits.nl. Once the equipment is set up next year and the adults (hopefully) return to the colony we will be able to see where they have been and will be able to follow their daily whereabouts again.
It is unlikely that the juveniles return to the Netherlands next year: they won’t start breeding until their fourth calendar year at the earliest and therefore can freely roam around Western Europe until that time. It will be exciting to at least follow them digitally which will give new insights in the dispersal of sub-adult Lesser Black-backed Gulls.
Whenever possible, I will try to give updates on the whereabouts of the juveniles if and when I receive that information.
Until then, please report any sighting of our IJmuiden gulls by submitting them (with photos if you have them) to Kees Camphuysen: kees.camphuysen (at) nioz.nl. Feel free to CC me on it as wel: gulls (at) vankleinwee.com.
About the project
The tracking study is part of an ongoing collaboration between UvA (Dr. Judy Shamoun-Baranes) and the 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.