return to possible Slaty-backed Gull in Davis
possible first winter Slaty-backed Gull
November, 1998; Davis, CA
FLIGHT SHOTS (click here for standing shots)
Fig 7 with close-up) These images show the primary pattern.
All of the inner webs are a bit paler than the outer webs, but they
are especially whitish on P6-7, and still rather pale through P3.
This is best for Slaty-backed and not right for Herring.
On Slaty-backed, the inner webs of P4-7 are palest,
while the inner webs of P1-4 are palest on Herring
(Pyle, P., Birder's Journal 6(5): 251). This pattern is unique
to Slaty-backed Gull, but possibly not diagnostic, as hybrids
(e.g., Herring x Glaucous-winged) may be able to replicate this.
Photo by Mike Rogers, copyright 1997.
Fig 8) That's the bird on the left. On the
left wing, you can see the underside of the
primaries as the wing folds forward. That's a
Glaucous-winged Gull on the right.
Fig 9) The upperwing was closest to Herring Gull, with a pale window that extended to P8. Note that P10 is all dark and P9 is mostly dark. Also note how much white there is at the bases of the outer retrices. Photo by Mike Rogers, copyright 1998.
Fig 10) Note the bill shape. It has pink at the base of the lower mandible. Also note the solid greater coverts and pale barring at the base of the outer retrices. That's a Glaucous-winged Gull behind it. Photo by Mike Rogers, copyright 1998.