delawarensis Ring-billed Gull

(last update: 10-03-2014 )

Coordinators:
Keith Mueller
Amar Ayyash
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 April
adult May
adult June
adult July
adult Aug
adult Sept
adult Oct
adult Nov
adult Dec

Ring-billed Gull delawarensis 1st cycle (2CY), April 18 2010, Boston, MA. Picture: David Sibley.

See David's site.

The variation in appearance in 1st cycle April birds comes from four main sources, which all interact:

  • the intensity (darkness) of feather markings on retained juvenal feathers
  • the degree of wear and fading of the feathers (which is related to darkness since pale feathers wear and fade more quickly)
  • the extent of dark markings on new feathers on the head and body (which seems to be related to the darkness of the juvenal feathers)
  • the extent of the spring molt which may or may not include wing coverts and tertials by this date

Besides variation in feather color and the intensity of wear and fading, birds can also differ in appearance depending on how many feathers have been replaced in the spring molt. The individual below has all replaced some wing coverts and tertials with new – grayish – feathers. A study by Kevin McLaughlin (2000) shows photos of Ring-billed (and Laughing) gulls that have replaced many of their wing coverts and tertials with new gray feathers, and his photos are from the fall. So it’s possible that these birds below actually acquired new gray coverts and tertials in their first post-juvenal molt last fall, although some additional replacement might happen in the spring.

Below: first-spring Ring-billed Gull. This bird is similar in bleaching, wear and plumage color, but has undergone a slightly more extensive molt, with a few new gray feathers among the wing coverts and tertials.