First Cycle With Herring x Lesser Black-backed Features

Adult Appledore Gulls (putative Herring x Lesser Black-backeds) are being reported frequently in Eastern North America these days. I have to wonder what percentage of these birds are F1 hybrids, backcrosses, aberrant Herrings or Lessers, or just completely different hybrids that are not on the radar at this time. In any case, the question of what 1st cycles Appledore Gulls look like persists and very little data is available.

Below is another set of photos of "what I imagine a 1st cycle hybrid" might look like. Ethan Gyllenhaal and I observed this individual in Northern Illinois on 23 Dec 2014 - neither of us was comfortable assigning a label to it:

Features that seem intermediate or atypical for one or the other species:

• Straight, thin, black bill more like LBBG than Herring.
• Neat, brown, plumage aspect with checkered wing coverts.
• Inner-primary window is not typical for Herring but too pale for LBBG.
• Thin tail band with white upperwing coverts, and whitish outer tail feathers.

Is this an Appledore Gull? Who knows. Off to the next one...