Heermann's Gull heermannii

(last update: 23-01-2018 )

Coordinators:
John Cant
Mars Muusse

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1cy June
1cy July
1cy Aug
1cy Sept
1cy Oct
1cy Nov
1cy Dec

2cy Jan
2cy Feb
2cy March
2cy April
2cy May
2cy June
2cy July
2cy Aug
2cy Sept
2cy Oct
2cy Nov
2cy Dec

3cy Jan
3cy Feb
3cy March
3cy April
3cy May
3cy June
3cy July
3cy Aug
3cy Sept
3cy Oct
3cy Nov
3cy Dec

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adult June
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adult Sept
adult Oct
adult Nov
adult Dec

Heermann's Gull heermannii adult, August 13 2018, Pismo Beach, California USA. Picture: Alex Abela.

See Alex's Flickr site for many more images, illustrating the plumage development in this species.

Old feathers heavily worn and bleached to faded pale brown. White tips of tail-feathers largely worn away.
Pre-basic moult started with new scaps and wing-coverts grey, strongly contrasting to old feathers. Central primaries missing / growing, with neat white tips again; outer primaries still old, also worn and bleached to brown.

P5/P9, P6-P7 growing, P8 missing. Moult started in outer secondaries and in central tail-feathers. Secondaries moult in two waves: one starting from the body (in the tertials) and one starting in the outer secondaries. The two moult waves will meet at about S12 in the last stage of the complete moult. Tail-feathers are shed and grown in centrifugal order, commonly R5 replaced last in line. White patches in the wing are mutant featyyhers, quite commonly found in Heermann's Gull.