Embedded Files
Locally rare species, with most records involving adult birds that may be returning to a particular region over a period of years. Molt patterns may be similar to Bonaparte's Gull; however, it is unclear if this species ever shows plumage features that may indicate a "second year" plumage.
First Cycle
June
July
August
September
The Great Lakes may be outside this species expected wandering limits for "first winter" birds, given how few nest in North America. (I.e., there is low probability of the few North American born Black-headed Gulls reaching our area, and we are perhaps too far from larger nesting colonies in Iceland / Europe to expect young birds to reach us).
October
November
December
January
February
March
April
May
The extent of black head markings in first spring birds is variable.
Second Cycle
The change from first to second cycle depends on the timing of the start of the inner primary molt. May/June is used here as an arbitrary cutoff.
June
July
August
September
Once their summer molt is complete, it is unclear if there would be any field marks to identify Black-headed Gulls in a "second year" plumage, and/or how frequently they occur. Examples of full adults are provided further below.
October
November
December
January
February
March
April
May
Adult
As noted above, it is unclear if Black-headed Gull has an identifiable second year plumage. Examples of full adults are provided by month below.
June
July
As a locally rare species, it is a bit of a mystery why some summer records involve adults in non-breeding plumage.
August
September
October
November
December
January
February
March
Black-headed Gulls are expected to obtain their black (brown) heads somewhat earlier than our local Bonaparte's Gulls.
April
May
Page updated
Google Sites
Report abuse