Learnin' Gulls - 07 Feb 2008
An ice jam in the river today brought lots of gulls in close, including a 2nd-cycle Glaucous Gull I found immediately upon arrival at the boat launch at the foot of Clinton St. (just north of BASF).
I had originally posted a sighting of an Iceland Gull, and believed it to be feeding next to a 1st-cycle Great Black-backed Gull on the ice, but after doing a bit of research I realized that I was mistaken (or so I think). This forced me to start evaluating all the flight shots of the fly-by gulls, and I decided to start researching the various developmental stages of the birds I photographed. So, I put together composite images of my flight shots so that I (and you) could evaluate the field marks that distinguish the different cycle-years of the local gulls. So without further adieu, let's start w/ the Glaucous Gull.
I originally believed it to be an Iceland Gull next to a 1st-winter GBBG and a 1st-winter Herring Gull. After reviewing Sibley's, Howell's, and National Geographic's books, however, I'm concluding a Glaucous Gull based on it's two-toned bill and short wing projection.
The dark gull in the middle appears to be a 1st-winter Herring Gull, while the slightly smaller and paler bird to its right is a 1st-winter Ring-billed Gull. A 1st-winter GBBG would have a more black-and-white appearance and a whiter head with an all-dark, heavy bill, so I conclude that the middle bird is a Herring Gull. By contrast, a 1st-winter Lesser Black-backed Gull is uniformly dark brown with a dark eye-patch on a lighter head.
Iceland Gulls appear to have all-dark bills their first and second winters, so the bicolored bill on this suggests Glaucous. (I'm not experienced enough to address hybrids, so I won't go there...).
Take a look at these 1st-winter Herring Gulls with its brown coloration, light heads and bi-colored bills. To me there is confusion here 'cause they could also look like GBBG's....
This bird appears to be a 3rd-cycle Herring Gull based on the amount of contrast between the yellow eyes and the brown coloration still on the neck, and just a touch of brown still on the wings. The P10 (?) primaries lack to white patches that are seen on the adult birds.
These birds appear to be non-breeding adult Herring Gulls based on the gray feathering still visible on the head and neck.
Other adults appear to be already in breeding plumage based on their all-white heads and bright red orbitals.
Ring-billed Gulls are easier to deal with relative to Herring Gulls. Here are some presumed 1st-cycle RBG's.
This one appears to be a 2nd-winter Ring-billed Gull based on the amount of gray on the head and the lack of white spots on the black primaries.
Here are some adult non-breeding Ring-billed Gulls based on the gray feathering in head and neck.
At this point I believe this one to be a female Mallard....
Please offer corrections if I appear way off! Thanks for looking!
