delawarensis Ring-billed Gull

(last update: 10-03-2014 )

Coordinators:
Keith Mueller
Amar Ayyash
Mars Muusse

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1cy June
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1cy Oct
1cy Nov
1cy Dec

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2cy May
2cy June
2cy July
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2cy Oct
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2cy Dec

3cy Jan
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1st cycle (juvenile): July

Juvenile Ring-billed Gulls (Larus delawarensis) are quite distinctive within their range, but anyone who's ever spent a little time observing this age group quickly comes to the realization that characterizing a "typical" youngster is no simple task.

Two juvenile types that may be thought of as opposite points along a spectrum. The following examples are limited to individuals thought to be from one to three colonies near the Chicago lakefront (all within an approximate 15 mile radius). Fledglings in this region begin to appear in late June and peak in late July.

Two Types:

Ghost-type (1) - As the name implies, this aspect is notably pale with a strong white ground color. The underparts, head and neck tend to show limited brown washing. The scapular feathers usually show an indistinct pattern. They're often boldly edged and based with white, giving the brown centers a golden appearance. The tertials can show a considerable amount of white, especially closer to the tips and along the edges, and the primaries are more likely to show pale tips; Both of these feather groups can show an intricate pattern of dark subterminal diamonds surrounded by white notches. 

Brown-type (2) - The general appearance of this type is a dark, chocolate-brown aspect. The most distinctive feature of this group is the large scapulars with solidly dark centers. The tertials are mostly plain and resemble the scapulars but are often a few shades darker. The greater coverts are more likely to show an even silver-gray throughout. The primaries are less often tipped with white compared to ghost-types. The underparts, head and neck show varying degrees of dark wash (this feature varies considerably and might be influenced by fading, wear and the onset of the first prealternate molt). Finally, I would suggest that this group is more likely to first acquire gray post-juvenile scapulars and upperwing coverts in late summer.

An important note here is that the aspects of these plumages quickly become altered shortly after the summer months due to the expected consequences of wear, bleaching and the commencement of the prealternate molt. And these two types appear to be on opposite ends of a variable spectrum- a spectrum that should be thought of as a work-in-progress.

Ring-billed Gull delawarensis juvenile, July 26 2013, Chicago, IL. Picture: Amar Ayyash.
Ring-billed Gull delawarensis juvenile, July 26 2013, Chicago, IL. Picture: Amar Ayyash.
Ring-billed Gull delawarensis juvenile, July 27 2014, East Chicago, IL. Picture: Amar Ayyash.
Ring-billed Gull delawarensis juvenile, July 26 2013, Chicago, IL. Picture: Amar Ayyash.
Ring-billed Gull delawarensis juvenile, July 26 2013, Chicago, IL. Picture: Amar Ayyash.
Ring-billed Gull delawarensis juvenile, July 13 2012, Cote Ste-Catherine, Canada. Picture: Julie Tremblay.
Ring-billed Gull delawarensis juvenile, July 27 2014, East Chicago, IL. Picture: Amar Ayyash.
Ring-billed Gull delawarensis juvenile, July 26 2013, Chicago, IL. Picture: Amar Ayyash.
Ring-billed Gull delawarensis juvenile, July 26 2013, Chicago, IL. Picture: Amar Ayyash.
Ring-billed Gull delawarensis juvenile, July 26 2013, Chicago, IL. Picture: Amar Ayyash.
Ring-billed Gull delawarensis juvenile, July 31 2013, Chicago, IL. Picture: Amar Ayyash.
Ring-billed Gull delawarensis juvenile, July 31 2011, LaSalle Park, Burlington, Canada. Picture: Miriam Bauman.
Ring-billed Gull delawarensis juvenile, July 06 2012, Chicago, IL. Picture: Amar Ayyash.
Ring-billed Gull delawarensis juvenile, July 04 2013, Blue Island, IL. Picture: Amar Ayyash.