Mew Gull Larus canus canus; heinei; kamtschatschensis; brachyrhynchus

(last update: March 12, 2012)

Mew Gull SVS 7146844 3cy/4cy, 14 December 1997 & 12 December 1998, Malmö, Sweden.

first image is figure 19: 7146844 (358/92,8) three-year old bird (3CY), lacking white tip on P8 and with black markings on primary coverts and alula. 14 December 1997. Compare to fig 24 in second image, for 4-year old plumage.

In their third year Mew Gulls are almost impossible to distinguish from four years old and older birds. The average three-year birds have mirrors on P9 and P10, black on six primaries (range 5-7) and white tips on P7 and P8 (about 50% also have a white tip on P9, see fig 18). Without exception the tail is all white in three-year old birds.
Retarded three-year old birds may be separated from advanced second-year mainly on the white tip on P8 and normally the mirror on P9 is fully developed. However, some second-year birds (3,3%) have a white tip on P8 (see fig 17) and some third-years do not show a white tip or have a very small one (two birds out of 18 in our data set). The third-year bird in fig 19 (below) lacks a white tip on P8, has a dark alula and small dark markings on wing-coverts. The same bird has been documented as four-year old (fig 24, second image) and even in this plumage it still lacks the white tip on P8 and shows the dark alula.

Figure from:
Is it possible to age subadult Mew Gulls Larus canus?
by: Kenneth Bengtsson & Lennarth Blomquist, publication in: Anser 2-42(2003): p 73-92.

below is figure 24, four-year old bird (4CY), with dark alula and lacking white tip on P8. 12 December 1998. Same bird as in fig 19.

We have 15 proven four-year old birds in the data set. The majority of these birds have two or three mirrors and black on six primaries (range 5-7). The alula is dark on three of them, while two birds have small dark markings on the primary coverts. Three out of 15 have a mirror on P8. All 15 birds have completely white tails. The most mature looking four-year old bird is shown in fig 23. We have also some less developed, retarded birds in this age-class; fig 24 (picture below) shows a bird with black in the alula, small markings on the greater primary coverts and lack of a white tip on P8. This black tip on P8 is normally an indication for two-year old birds and the bird in fig 24 is the only older birds in our material that shows this character.