 |
| Herring with virtually no mirror on p10 (still growing). P4 with small speck on outer web and marked p-coverts/alula suggest a 4th cycle type. Michigan City, IN. 07 October 2016. |
 |
| Same individual above. A mostly adult-like bird near finishing prebasic molt. |
 |
| Another adult type with a large p10 mirror showing several white "spots" on the underside of the primary. P-9 with a weak thayeri pattern. Michigan City, IN. 07 October 2016. |
 |
| Adult type Herrings. Left bird already in nonbreeding condition while the bird on the right has bright legs and bill. The most natural explanation for this is hormonal variance. |
 |
| Sub-adult Herring with the often-seen black ink spot on the tertials. Also of interest on this bird is subtle hints of wavy barring on the neck/breast. Although this is most commonly seen on Glaucous-winged Gull, Herrings too can show it. |
 |
| 1st cycle Herring with ~90% of scapulars 2nd generation. Rare is to see a few (inner) upperwing coverts replaced already (likely PA1). Bill is beginning to pale. Also of interest on this bird is a paling forehead, an attribute often found in similar-aged California Gulls. |
 |
| 2nd cycle Herring Gull. A very obvious marbling to the greater coverts and tertials, unlike in 1st cycle birds. The primary tips are rounded (and still growing - see next image). |
 |
| A still largely marked tailband, with reduced markings on the upper rump. The inner primaries are more silvery than is seen on 1st generation primaries. The axillaries are mostly white as expected at this age. |
 |
| 1st cycle with ~100% of scapulars replaced. Somewhat unusual is a few wing coverts (median and greater) have been renewed. This usually doesn't take place with the majority of hatch year herrings that I encounter. A better angle of this in the photo below.. |
