Mew Gull, Adult: Golden Gate Park, San Francisco, California, USA - 13th November 2009: Note the slender and plain lemon yellow bill with only a small dusky spot on the gonys; most adult Common Gulls at this time of year have a sub-terminal band.
The head, neck and breast are dusky brown forming a diffuse hood which Common Gull lacks; adult winter Common Gulls tend to have fairly strong head and neck streaking which does not extend onto the breast.
The white primary tips are fairly small perhaps indicating that this is a near adult rather than full adult?
Mew Gull, Adult: Golden Gate Park, San Francisco, California, USA - 13th November 2009: A different bird to the previous individual. The head streaking is a little harsher on the crown, hind-crown and around the ear coverts but as above not the diffuse wash down onto the breast and the plain, slender yellow bill.
The legs are distinctly yellow.
Mew Gull, Adult: Golden Gate Park, San Francisco, California, USA - 13th November 2009: Although this birds eyes look dark they have a strange, brownish dark flecked quality; the black pupil stands out. The head streaking is boldest on the crown and around the ear coverts and as with the previous birds the dusky brown wash to the breast.
The primary tips are small possibly indicating that the bird is not fully adult however note the largish, pointed mirror to the under-side of P10.
Mew Gull, Adult: Golden Gate Park, San Francisco, California, USA - 13th November 2009: A close up of the head shows the brown eye and black pupil well. This can vary to almost completely dark to several shades lighter.
Note the extent of the head streaking; less diffuse on the forehead whilst the rear of the crown and ear coverts becomes a little heavier though never becomes striking as in Common Gull of this age. The bill lacks any sub-terminal bands seen on many Common Gulls at this time of year.
Mew Gull, near Adult: Golden Gate Park, San Francisco, California, USA - 13th November 2009: Aged as a very near adult, at rest would be an adult, due to the dark marks on the outer greater primary coverts and the very small black spots in the outer rectrices.
The primary pattern:
- P10 has a large white mirror, obviously split by the shaft and lacks an obvious white tip (also suggestive of the bird being a near adult)
- P9 has a fairly small split mirror and a lot of black to the feather tip which lacks a white tip.
- P8 is all black with the exception of the smallest white tip
- P7 has a clear white tip and an obvious white moon on the inner web
- P6 has a large black tip and a white moon across both webs
- P5 Broad black band; white moon and large white tip
- P4 has a white tip and a split black band; appears as a black notch on the outer edge of the inner web and a black crescent on the outer web.
Mew Gull, Adult: Point Pinos, Monterey, California, USA - 25th November 2009: The bill is short and yellow with a slight dusky mark at the gonys. This birds eyes look rather darker than those above. Note the extent of streaking on the crown and sides of the head with the mottling extending down the breast.
This bird also has a rather large white tertial crescent which is short on the outer feathers, clearly revealing P5 beneath. P5 shows a large white tip and broad black band.
P6-P7 are black with obvious white tips but also note especially the the white of P7 is just visible behind folder P6. Common Gull doesn't have white that extends this length of P7.
The mirror on the underside of P10 is large and isolated.
Mew Gull, Adult: Point Pinos, Monterey, California, USA - 25th November 2009: Here's a great example of the wing formula of an adult Mew Gull.
- P10 looks a little short and may still be growing. It has an extensive white mirror and no white tip
- P9 has a large white oval mirror and no white tip. Note the greyish tongue extension along the inner web and that the black on just reaches the primary coverts on the outer web
- P8 is black and has a white tip
- P7, laying across P8, shows a bold white tip and a white 'extension' along the inner web; Common Gull doesn't have this extension eating into the black.
- P6 is black with black bleeding along the shaft creating a central point or spur, Common Gull probably does not show this
- P5 has a broad black band and extensive white tip.
Mew Gull, Adult (left): Bodega Bay, California, USA - November 2009 and Common Gull, Adult (right) Nimmo's Pier, Galway, Ireland February 2009:
Comparison image, the Common Gull is currently the best wing spread shot image I have of the species.
- P10: Extensive white mirror 'bleeding' along the outer web on the Mew Gull where as remains more of an oval shape on Common Gull. Also the black of the primary does not reach the primary coverts on the inner web where as on the Common Gull it does.
- P9 on the Mew Gull the mirror is large with a slight pointed inflection to the basal tip; squarer ended on the Common Gull. On the Mew Gull not the black falls well short of the primary coverts, very nearly reach the primary coverts on the Common Gull. Furthermore there is a small white moon between the black of the primary tip and the grey of the basal half. This seems typical of adult Mew Gulls.
- P8 on the Mew Gull has an extensive white inner web between the black tip and the grey basal half, the black extends along the outer web creating a black 'spur'. As can be seen on the Common Gull the feather tip is completely black save for the very tip itself. This feature is key for Mew Gull adults from Common Gulls.
- P7 is black but with a large white moon and triangular white feather tip. The tip of the Common Gull is more extensively black, has only a small white moon and a small white primary tip.
- P6 large white feather tip and white moon on the Mew Gull; lack of white moon on the Common Gull
- P5 has a diffuse black band on the Mew Gull, pointed wedge shaped on the outer web and crescent shaped on the inner web, again bold white moon. On the Common Gull there is also a large band but is block shaped on the outer web and crescent shaped on the inner web.
- P4 The Common Gull has a small dusky mark in the outer web which Mew rarely shows.
Thus the Mew Gull has less black more white in the wing tips than Common Gull with what can be described as whitish tongues. P8 is probably the deal clincher with it being mostly black on Common Gull and extensive white tongue/moon on Mew Gull.
Mew Gull, Adult: Point Pinos, Monterey, California, USA - 25th November 2009: Here the dark hooded affect is almost a deal clincher on its own from Common Gull however note the following:
- Short plain unmarked yellow bill
- The pale tongues extending along the inner webs of P8 (especially) and P7.