07 December 2015

Cleveland BSBO Pelagic Redux

I attended the December "pelagic" trip out of Cleveland offered by the Black Swamp Bird Observatory this past weekend. We were hoping for a "nice" gull but Lake Erie was calm and mild. One thing is for sure, the northern gulls have not arrived! The highlight came after the trip where I was able to relocate an adult Little Gull at Harbor Point, but it was a distant bird with no good photos to share. Later in the afternoon, shortly before sunset, a group of us watched a juvenile Pom Jaeger half-heartedly rip pass a group of Bonaparte's in the distance.

So when all else fails and there are no special gulls around, one has the common species to fall back on as there is ALWAYS something neat to see. Herrings, Ring-billeds and Bonaparte's - love 'em and learn them well!

Herring Gulls

Standard "Great Lakes" or "Interior" American Herring. Single mirror, black on p9 extends to both webs, and full subterminal "w-band" on p5.
Likely age-related, but the marked p3 is very unusual for a bird this mature. With an all-white tail and clean wing coverts, the only sign of immaturity is the few streaks on the outer greater primary coverts. 
Another adult-type (sub-adult?) Herring with just a couple streaks on the G-P coverts. Note how the black extends almost all the way to the primary coverts on p8 - this is not typical of definitive adults, even those seen in the Great Lakes. P4 has a broken band. Again, my assumption is the pattern on this wingtip is age-related.
Same individual pictured above.
Textbook, 2nd cycle American Herring.
1st cycle Herring with slightly less contrasting inner primaries than average, although this may be due to the angle. Note how the window contrasts a bit more on the left wing. Scapular molt nearly complete.

Here's a neat composite I put together to demonstrate how the shape of the hand (short and round versus long and narrow) can change in flight. It also shows how the two outermost primaries may appear to have round tips in one instance, and then pointed tips in another instance. These photos were taken - literally - seconds apart.

American Herring Gull (1st cycle).

Ring-billed Gulls

An "old" Chicago Ring-billed. This blue patagial-tag bird was banded at the now non-existent Lake Calumet colony on the southeast side of Chicago in 2007. Those birds were displaced (30.000 + pairs). I've not seen a blue tag on the Chicago lakefront in some time, although I have seen them in Wisconsin, Indiana, Michigan and now Ohio in the last couple of years.
At least 8 years old, this adult shows no p9 mirror and has dark shaft streaks on p6-p8. The greater primary coverts also have a few dirty smudges which may be cosmetic.
Same individual. Relatively large mirror on p10 but no mirror on p9. Note the black at the base of p10. It's common to see this part of p10 exposed with no greater primary covert covering the outer web. There was a time when I thought it was the primary covert itself that was black.
Maarten van Kleinwee was keen to pick out the "false" or "pseudo" mirrors on the underside of p10 on this bird. More than any large white-headed gull I know, Ring-billeds will often show these wannabe mirrors on p10, p9 and even p8.
False mirror on the underside of the innerweb of p10
Here are two adult Ring-billeds showing these false mirrors, photographed on the same day (05 December 2015):

A small false mirror on the underside of p9 and p8 on two different birds. Note both of these adults are without mirrors on p9 and have full bands on p5, similar to the blue-tagged adult above. Compare this with the individuals below.
A "white-winged" Ring-billed, if you will. Two large mirrors and apparent white tongue tips on p6-p8. Note the fainter band on p5. Is this age-related?
Another "white-winged" Ring-billed Gull. Large mirrors on p9-p10, and apparent white tongue tips on p6-p8. Black marks on p5 absent.
Same indvidual above. One has to wonder how old is an adult with such a wingtip.
When you have this many Ringers to pick through, you're bound to start looking for patterns!

Bonaparte's Gulls

Adult holding its legs out and down in typical plunge-dive formation. Scapulars closing the gap between wing and body.
Adult with unmarked p9. Note the absence of markings on p3.
2nd cycle "type"? Black outer edge to p9 and small spots on greater primary coverts. Interestingly, though, note the broken band on p3 and overall thicker black subterminal trailing edge to the primaries (compare with the bird above).

Another 2nd cycle type. Note the black markings on the tail and secondaries, black sliver on p9, and most intriguing, the marked innermost primaries. Do older Bonaparte's show less black on the innermost Ps? I think the reasoning makes sense when considering studies that have been conducted on known-age gulls, in general, but it'll take a few more thousand observations, and some banded birds to be sure!
1st cycle Bonaparte's Gull
1st cycle Bonaparte's Gull.

Glamour Shots