On Saturday June 22 I photographed a second-calendar year Baltic Gull Larus fuscus fuscus on the beach of Noordwijk aan Zee, The Netherlands, together with fellow birder and gull enthusiast Martijn Bot.
Twenty minutes later, we again photographed a second-calendar year Baltic Gull, this time just off the beach at the base of a dune but close to where we took our first photos. At the time we believed that we photographed the same bird twice, especially because of the similarities in appearance: a dark brown bird with yellow bill, yellow-tinged legs, and with fully replaced wing and tail feathers.
Now, after studying all the photos that I took in more detail, I firmly believe that we did indeed see 2 different individuals!
Let me talk you through the differences between bird #1 which we photographed on the beach and bird #2 which we photographed near the dunes.
- Long and elongated appearance with a pronounced breast (male?)
- Rather long bill
- Dark, uniform looking scapulars and wing coverts (but photos taken in dark conditions and light drizzle)
- Distinctive streaking at the top of the head
- Tertials with a dark center and broad white fringe
- Body shape less bulky, comes across as smaller (female?).
- Bill slightly shorter than individual #1.
- Most scapulars and wing coverts look lighter in color (but this may be partly influenced by better lighting conditions and a difference in photo processing) and seem more patterned/less evenly colored. They contrast with darker looking (3rd-generation?) feathers.
- Only slight streaking is visible on the top of the head.
- The tertials are more patterned and have a smaller white fringe.
Upper wing pattern
The central greater coverts in the right wing of bird #1 are much darker than the inner and outer greater coverts, something which bird #2 does not show (this characteristic is actually what triggered the feedback on the forum and made us look closer at our photos).
Bird #1 seems to display a lighter underwing than bird #2, but because of the different lighting conditions and angles I find it difficult to make a definitive conclusion.
Upper tail coverts and tail pattern
One of the more distinctive differences between the 2 individuals is visible in the upper tail coverts where bird #1 shows a much whiter and less barred pattern than bird #2. Although difficult to see, the pattern on the outer tail feathers also seems different.
Lower body pattern
Another distinctive feature is the pattern on the lower body, especially on the flanks towards the tail. In bird #1 this area is largely unpatterned whereas in bird #2 a dark pattern is visible.
Bill coloration and pattern
The bills of both birds seem to be equally brightly colored and with a black tip that is of equal size. In bird #2 slightly more of the gonys spot is visible but because both birds were photographed from different sides it is hard to compare the bill pattern.
Again, difficult to judge from my photos but if anything I would say that the legs of bird #1 are more yellow than those of bird #2.
Why did we not spot this ourselves?
I can’t talk for Martijn of course, but up until today it hadn’t occurred to me that we were dealing with different individuals, let alone that I had to look for any differences. And because I wasn’t expecting to see any differences, I wasn’t looking for them. This was also fueled by the fact that both birds were seen from different sides, which makes comparing differences in features more difficult.
When I went to Noordwijk that day, my main objective was indeed to try and find a second-calendar year Baltic Gull, knowing that several individuals had been seen at that location already, but never more than one at a time. The individuals that had been seen up to that moment all looked very different, from pale brown and white-headed to dark brown, white-headed and with a greenish bill base,
I also knew that if I was going to see one I needed a fair dose of luck because we are talking about spotting a single individual in a flock of 5000+ gulls.
When we did eventually spot one and later another which looked very similar, we immediately assumed that it was the same individual, mainly I think because we were expecting to see one of the white-headed individuals.
So it turns out that Noordwijk has given us a nice surprise by letting us see not one but two rare Baltic Gulls that day (albeit with a little help from some friendly directions on the forum for which I am grateful).
Martijn’s compilation of the differences