30 November 2017

Flight Feather Molt in November Lake Michigan Iceland Gulls

A short note on flight feather molt regarding mid-late November Iceland Gulls on southern Lake Michigan. Roughly 70% of adult types are still growing p10 before Thanksgiving, and about 40% of these individuals are also growing p9 at this date. Of birds growing p10 and/or p9, about a third of these individuals are finishing inner secondary molt (anywhere from what appears to be 3-6 secondaries remaining).

A few examples from last week:

p9-p10 still growing as are the inner secondaries. Lake County, Illinois. 19 Nov 2017. Photo 1 of 2.

Same individual above. Photo 2 of 2.

Thayer's. A relatively small p9 mirror. p10 growing as are many inner secondaries. 

A paler individual showing thayeri and kumlieni wingtip characterisitcs. P9 almost fully grown. P10 still growing. Lake County, IL. 19 Nov 2017.

A Kumlien's type. P10 still growing. Secondaries fully grown. Lake County, IL. 19 Nov 2017.

These next two individuals are from Lake Superior a week later. I was reassured by Peder Svingen that a good number of early Iceland Gulls (namely, thayeri subspecies) arrive in the Fall with p9/p10 growing on Lake Superior. His impression of their molt state was similar to mine with Lake Michigan birds.

Thayer's. Primaries grown but the secondaries are delayed. Douglas County, WI. 25 Nov 2017.

Thayer's. P10/p9 growing. Inner secondaries also molting. Douglas County, WI. 25 Nov 2017.