#larusdelawarensis

[ethanm8n]

Differences Between Ring-billed and Short-billed Gulls

September 29, 2024

Misidentifications I see on the Metro Vancouver eBird somewhat frequently involve Short-billed and Ring-billed Gulls, especially juveniles and first cycles (juveniles that have begun the first pre-alternate/pre-breeding moult).

Adults are the easiest to separate.

Ring-billed Gull gets its name from the black band towards the end of the bill. At most, Short-billed Gull will have dark markings in a similar position, but never a complete ring. Sometimes the bill tip of some Short-bills is yellow, and the basal portion greenish yellow.

Adult Ring-billed Gull in breeding plumage. Note black band around outer bill, pale yellow eye.

Adult Short-billed Gull in non-breeding plumage, undergoing prebasic/post-breeding moult. Head is all white during breeding season, like Ring-billed Gull. Note dusky, speckled eye.

Also, Ring-billed is larger than Short-billed, has a lighter grey mantle (upper body) and pale yellow eyes instead of dusky/speckled.

In flight, Ring-billed has smaller wing mirrors on p10-p9 than Short-billed Gull (white patches near the top of the outer two wing feathers).

Ring-billed gull in prebasic/post-breeding moult. Note limited wing mirrors on outer primaries.

Short-billed gull in prebasic/post-breeding moult. Note extensive wing mirrors on outer primaries.

The juvenile plumages of both species are reliably identifiable as well.

Ring-billed is whiter overall, with contrastingly dark brown patterning on upper body, wings and behind the tail. Short-billed is grey-brown overall, bleaching whitish over winter.

Both species's bills start off dark, then become pink at the base. The dark tip of Ring-billed is more clearly demarcated.

[coffeenuts]

[flwgt07]

Big yawn! Boring!... Ring-billed gull / Goéland à bec cerclé / Larus delawarensis #RingBilledGull #GoélandÀBecCerclé #LarusDelawarensis #BirdsOfGeorgia #Birding #BirdPhotography #ColonialCoastBirdingTrail #GeorgiaBirdingTrails #JekyllIsland #Brunswick (at Jekyll Island) https://www.instagram.com/p/CnLGlueOsdn/?igshid=NGJjMDIxMWI=

[reptilearts]

Mood 🖤 #ringbilledgull #gull #Larusdelawarensis https://www.instagram.com/nadilyn_beato/p/BvSzPRCnJ2P/?utm_source=ig_tumblr_share&igshid=xjo94tlcu720

[thehoneyseals]

Day 37: More Seagulls . . . . . Hanging out on a post. 11:26 AM . . . #thehoneyseals #honeyseals #ringbilled #gull #ringbilledgull #larus #delawarensis #larusdelawarensis #seagull #superbowlsunday #SuperGullSunday #sealpeople #gullpeople #seagullpeople (at New York, New York) https://www.instagram.com/p/CLMuZyEDKmW/?igshid=e6dyg78jful9

[donpue]

Gaviota pico anillado N. Científico: Larus delawarensis E. Name: Ring-billed Gull #GaviotaPicoAnillado #gaviota #larusdelawarensis #larus #ringbilledgull #gull #Esenada #BajaCalifornia #México (en Ensenada, Baja California) https://www.instagram.com/p/BzhWkghn0GC/?igshid=1e9ks29xesfmv

[wabisabiwildflower]

Itchy by Dendroica cerulea on Flickr.

[rimcarthur]

Incoming! on Flickr.

A lady was feeding bread to the trumpeter swans, ducks and gulls at the Marina on Hamilton bay. This ring-billed gull was dropping in for his share. Feeding bread isn't the best idea, lots of bilk not much nutrition. Seed is always a better idea. Larus delawarensis Some Ring-billed Gull nests at study sites in California and Oregon contained pebbles the size and shape of gull eggs. The parents apparently pulled the pebbles into their nests from the surrounding ground, mistaking them for eggs gone astray.

[rimcarthur]

We have lift off. on Flickr.

We got a little too close to this ring-billed gull when we were out on the pontoon on Friday. After a running start it lifted off, gave us the evil eye and flew away. Larus delawarensis Most Ring-billed Gulls nest in the interior of the continent, near freshwater. Migrating Ring-billed Gulls apparently use a built-in compass to navigate. When tested at only two days of age, chicks showed a preference for magnetic bearings that would take them in the appropriate direction for their fall migration. source - Cornell Lab of Ornithology.