31 January 2015

Primary Molt in Wintering Lesser Black-backeds: Florida

A significant percentage of adult/near-adult Lesser Black-backeds from east-central Florida (roughly 28.5"N, 81"W) showed variable p10 lengths in late January, 2015. Seventeen out of twenty-six also showed p9 feathers that were not fully grown.

A. Short-wing appearance. 
B. P10 mirror on underside of far wing still emerging. 
C. Pale-end bird.
D1. Green F05 with almost fully grown p10.
D2. P10 on left wing appears longer than right wing.
E2. Note how p10 appears shorter than the previous photo when the
primaries are folded closer together.
F1. Only about 30% showed mirrors on p9.
F2. Mirror on left p9 now unobstructed (see previous photo).
G1. Very similar to bird F (more black on bill).
H2. Asymmetric p10 growth on left and right wings.
H3. Very short left p10 (tip protruding under the greater primary coverts).
K1. Just about fully grown length on p10.

Adult with salmon-colored legs. P8 longest primary.
What this all means when trying to narrow down migration distances (or subspecies) is yet to be learned. But there is an ID implication that should be kept in mind: adults with primaries not fully grown appear shorter-winged. The overall impression of wing structure on standing birds is similar to American Herring (at least this would be so earlier in the season. Hence, there's potential for confusion where points may be given to a "hybrid" over pale-end graellsii. To make matters more interesting, some of these adult types may show leg color with pinkish tones.