Primary pattern variation in adult Common Gull White E21C – 2013/2015

This weekend I came across Common Gull Larus canus canus White E21C which was ringed as a 2nd-calendar year in December 2010 in Zoetermeer, the Netherlands. This makes 2015 its 7th calendar year so it is well into its adulthood.

I have come across E21C regularly over the previous years and when comparing the images that I took with those from March 2013, 2 things caught my eye:

  1. The primary coverts still show black markings. We usually treat this as an indication that a gull is a young adult but White E21C proves that full adults can also still display these markings.
  2. The primary pattern has changed, mainly in the left wing. The photos of 2013 clearly show black markings on the outer web of P4 and on both webs of P5, but in 2015 no black can be seen on P4 and in P5 only the outer web has a black mark. In the right wing, P5 has not changed but again the black mark in P4 has disappeared.

Here is White E21C in March 2012 as a 4th-calendar year:

W-E21C-20120309

…in March 2013 as a 5th-calendar year:

W[E21C]_16Mar13

…and in March 2015 as a 7th-calendar year:

W-21C-20150320-2

Here is a comparison of the left wing. Note the black markings on the primary coverts and the differences in P4 and P5:

W-E21C-2013-2015-primary-pattern

Finally, some more photos taken this weekend (March 2015) in Zoetermeer, the Netherlands:

W-E21C-20150320-4

W-E21C-20150322-2

W-21C-20150320-1

I find this primary pattern variation in indvidual gulls fascinating to document and it is something that I had already observed in a European Herring Gull. I am looking forward to following E21C over the coming years.

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