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

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

adult: August

Birds in last stage of the complete moult (PB moult in summer) which now has aarived at the outer porimaries and central secondaries. In the wing-coverts, the moult gap in the central Gc and the small feathers in the carpal edge are the last to be replaced.

In August, birds are in active tail-feather moult, which normally show a centrigugal sequence (the central tail-feathers sehd first and moult progresses outwrads). It will reach the end by September, with the new feathers again showing neat bold white tips. Often, R5 is the last to be moulted. In August, typically birds show missing tail-feathers and some very worn and bleached brown old feathers, which lack the bold white tips of fresh feathers.
Moult in the secondaries started a couple of months ago in the upper tertials (which, technically are part of the secondary row at the body side); and another moult wave started more recently at outermost secondary S1, furthest away from the body (S1 shed approximately when P6 is halfway). These two moult waves will progress rapidly in August and September (almost feather shed as small blocks) and the two will meet at about S12 by early October. In the new secondary row, check for a small indent near the body, which are the last feathers to be growing in, together with P10. But that will be October, now, in August, many birds show a very irregular trailing edge at the hindwing, due to missing secondaries and primaries.
Primary moult started in early summer, when P1 was shed and PB moult commenced; now, in August and the first half of September