During my stay in San Diego in April (see San Diego Trip Reports), the most abundant species present was the Western Gull (Larus occidentalis).
It’s a beautiful, large gull with dark eyes, pink legs and a bill with a distinctive bulbous tip. Adults are easily recognizable due to the fact that they are they only gull in their range with such a dark plumage.
Although it was the main species that was present, numbers were quite low during my visit. I stayed near the Sea Port Village (mainly the area between the Convention Centre and the USS Midway) and I don’t think I saw more than 30 gulls a day or so.
One reason I think this was caused by was that the area is heavily dependent on tourism and was therefore kept very neat and tidy. Feeding birds was a big no-no and apart from the odd picnicker feeding them scraps, there was just nothing for them to feed upon.
That didn’t mean that they were not in the area though. After returning from a whale-watching trip one day we came past a fishing vessel in the Bay area which was followed by a few hundred Western Gulls or so.
Out of all the age groups, 2nd-calendar year olds were present in the highest number.
When analyzing my photos afterwards, I was actually surprised to find out that I had photographed some 40-odd individuals of this age, proving that there was a high turn-over of individuals.
Plumage-wise, what struck me most was their heavily streaked head.
Almost all individuals had started their moult to second pre-basic plumage (the start of their second cycle plumage), which was obvious by the median coverts that had been dropped and the dark, second-generation scapulars (and sometimes median coverts) that were visible.
Exceptions to the rule
As ever with gulls, some individual stood out because they didn’t conform to the general rule.
More photos of second-calendar year Western Gulls can be seen on my Flickr page.
Videos of second-calendar year Western Gulls can be seen on my YouTube channel.
Third-calendar years (and sub-species)
I came across several third-calendar years (some 15 or so), which could be aged by a mix of adult characteristics (mostly yellow bill, hint of a red gonys spot, yellow orbital ring, and pink legs), and sub-adult characteristics (brown wing coverts and primaries without mirrors or apical spots).
The range in gray tones in the scapulars was a first indication of the existence of the 2 subspecies of Western Gull:
- Larus occidentalis occidentalis with a lighter shade of gray (Kodak gray scale 7.5 – (9) 9.5). Range: between Central Washington and the Monterey Peninsula, California.
- Larus occidentalis wymani with a darker shade of gray (Kodak gray scale (9) 9.5) – 10.5 (11). Range: generally south of San Francisco.
More photos of third-calendar year Western Gulls can be seen on my Flickr page.
I’ve identified only one fourth-calendar year Western Gull, based on its adult appearance but with a large amount of black in the alula and primary coverts .
Being unfamiliar with this species and its full range of characteristics, it’s dangerous to age individuals with certainty, but based on my experience with large gulls in Europe I believe the following individuals to be youg adults, possibly 5th-calendar year individuals. This is mostly based on the presence of black in the alula and primary coverts (but in a lesser amount than can be seen in the 4th-calendar year type above).
To end this rather long post, some photos of beautiful adults.
More photos of adult Western Gulls can be seen on my Flickr page.
I was also able to capture some pair bonding behavior on video, including choking, head-tossing and mew-calling:
Gulls of Europe, Asia and North America Klaus Malling Olsen and Hans Larsson
Gulls of the Americas Steve N.G. Howell and Jon Dunn
Molt in North American birds Steve N. G. Howell