These first-cycle, second-calendar year Thayer’s Gulls Larus thayeri were seen during the Gull Frolic 2014, held on 15 February at Winthrop Harbor, Illinois, USA.
From a Western-European/Dutch point of view, it shouldn’t be too difficult to pick out such a bird from a flock of European Gulls (Herring or otherwise), right?
Some of the main identification features include:
- Uniformly coloured, pale-brown plumage (including chest and head) with little contrast (paler than a European Herring Gull but darker than an Iceland Gull or Glaucous Gull of the same age)
- Dark-brown outer primaries with light crescent tips
- Juvenile scapulars
- All-black bill
- Almost fully dark tail
- Pale window on inner primaries
- Heavy, dense barring on uppertail and undertail coverts
Note the broken tips of primaries P9 and P10 in the right wing and the light spots on the central tail feathers.
Gull Research – 2nd-calendar year Thayer’s Gull in February