1st-Cycle gulls still in juvenile plumage in January

(plus some interesting tail patterns)

January turned out to be an interesting month this year with several observations of second-calendar year gulls still in (predominantly) juvenile plumage.

This is exciting because this is a moult pattern (or lack thereof…) that is indicative of gull species that originate from northern Europe (Scandinavia, Russia, etc). Think Scandinavian Herring Gull and Baltic Gull.

Needless to say, the most exciting observation (on January 13) was indeed of a Baltic Gull (Larus fuscus fuscus) of which I wrote earlier this month.

Putative 2nd-calendar year Baltic Gull. Utrecht, The Netherlands, 13 January 2013.

Putative 2nd-calendar year Baltic Gull. Utrecht, The Netherlands, 13 January 2013.

The previous day I had already seen my first individual of the month in the form of a putative Scandinavian Herring Gull (Larus argentatus argentatus).

Putative 2nd-calendar year Scandinavian Herring Gull. Leiden, The Netherlands, 12 January 2013.

Putative 2nd-calendar year Scandinavian Herring Gull. Leiden, The Netherlands, 12 January 2013.

Note the fresh looking feathers (no worn or abraded fringes) and only 3 replaced scapulars. These features combined almost certainly make this a Scandinavian Herring Gull. From the small size of the body, head and bill I would make this a female too.

And today I saw another putative Scandinavian Herring Gull, but this time a much more robust looking individual:

Tatus-2cy-30Jan13a

Putative 2nd-calendar year Scandinavian Herring Gull. Leiden, The Netherlands, 30 January 2013.

Tatus-2cy-30Jan13c

Putative 2nd-calendar year Scandinavian Herring Gull. Leiden, The Netherlands, 30 January 2013.

Again, this individual is in almost full juvenile plumage with a few missing scapulars and only one second-generation scapular on the left side.

Tail patterns

Interestingly, this individual also showed a barred tail pattern, not something that can be commonly seen in first-cycle Herring Gulls:

Putative 2nd-calendar year Scandinavian Herring Gull with barred tail pattern. Leiden, The Netherlands, 30 January 2013.

Putative 2nd-calendar year Scandinavian Herring Gull with barred tail pattern. Leiden, The Netherlands, 30 January 2013.

I’ve only seen a similar tail pattern on a first-cycle Herring Gull twice before:

1st-Calendar year European Herring Gull with barred tail pattern. 4 September 2010, Leiden, The Netherlands.

1st-Calendar year European Herring Gull with barred tail pattern. 4 September 2010, Leiden, The Netherlands.

2nd-Calendar year European Herring Gull with barred tail pattern. 10 April 2010, Leiden, The Netherlands.

2nd-Calendar year European Herring Gull with barred tail pattern. 10 April 2010, Leiden, The Netherlands.

The origin of both of them is unknown. Is it indicative for Scandinavian Herring Gulls?

In comparison, this is the tail pattern that I’m used to see for this age group (note the much wider subterminal bar):

1st-Calendar year European Herring Gull with regular tail pattern. 17 September 2011, Leiden, The Netherlands.

1st-Calendar year European Herring Gull with regular tail pattern. 17 September 2011, Leiden, The Netherlands.

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