delawarensis Ring-billed Gull

(last update: 10-03-2014 )

Keith Mueller
Amar Ayyash
Mars Muusse

Index ORG

ring projects

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

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

Below: first-spring Ring-billed Gull. This bird was the darkest one seen, and has very strongly-marked and fresh-looking wing coverts and tertials. Presumably it started out last fall with relatively dark markings on these feathers. Looking at the tertials we can see the effects of wear, and how melanin (dark pigment) actually strengthens the feathers so that the white parts wear away first.