Heinii Common Gull? Mirfield UK (1 Viewer)

Nipped down to Sands Lane to see if the Ring Billed Gull was there. It wasn't but there was a very dark mantled common gull on the ice. Any comments appreciated.

If you are sure that this isn't the Ring Billed Gull then I have no idea.

RBG has a pale Iris and apaler mantle than CG.

Some notes on Heinei from here

Features that suite ssp. heinei in few of the individuals are without being diagnostic:

1) long-winged appearance where the very long and slender wings are held slightly dropped on standing gull. On folded wing p5 is obviously exposed behind the longest tertials in a degree rarely mirrored by any canus and p10 is the longest primary
2) retarded moult in February with massive presence of juvenile upperpart feathers which is only seen on northern canus breeders
3) heavy markings and barring on hind neck, breast and along flanks where canus often has finer markings and a more striated patterns without the washed out appearance of some of these gulls
4) less marked underwing coverts than in canus
5) more contrast in upper wing than on typical canus with lesser upperwing coverts darker brown than in canus and greater upperwing coverts darker brownish-tinged with weak dark subterminal spot and gradually darker towards outer coverts (most obvious in flight)


and some pictures
http://gulldk.blogspot.com/2009/08/russisk-stormmage-larus-canus-heinei-4k.html

James Thomas said:

Nipped down to Sands Lane to see if the Ring Billed Gull was there. It wasn't but there was a very dark mantled common gull on the ice. Any comments appreciated.

Click to expand...

Was it really darker, or is that an effect of the light?

Twas dark, think there is a little effect from the angle but not entirely attributable. I've put the same shot up with some common gulls at about the same angle, slightly darkened but nothing compared to the bird in question. The bird next to it is getting a full broadside of the sun.

Just checking for better shots, shouldn't have been there - taking the lads to Grandma's on a present run and popped in to feed the ducks a loaf of bread. Couldn't give it proper time and attention.

I had a similar bird back in march, which was very dark-
http://birdforum.net/showthread.php?t=187222

James Thomas said:

Twas dark, think there is a little effect from the angle but not entirely attributable. I've put the same shot up with some common gulls at about the same angle, slightly darkened but nothing compared to the bird in question. The bird next to it is getting a full broadside of the sun.

Click to expand...

Hi Jim - thanks for posting your pics for comment. In response, firstly, IMHO the dark grey apparent in the pic is predominantly an effect of the back being in shadow, the head being angled slight away from the camera (compare shadow lines on ice from other birds); not obvious, but I believe this is the case. Even if it were not in shadow a small amount of angle in relation to the direction of the light can make quite a difference. See apparent variation in attached, from my local roost on Saturday, this was at sunset and it was overcast so there was no bright directional lighting, nevertheless some with mantle shielded from west (left) look darker, and vice versa. This is compounded by a degree of variation in mantle shade of apparent canus even in identical conditions. You also need to be sure the feathers are not damp (from washing) though that does not seem to be the case here.

Secondly, the henei features your quote earlier are from an article titled 2CY, so these are what you're looking for on a 1st-winter bird; only the structural features are really relevant to your bird. From the thick sub-terminal band on the bill yours is actually a 2nd-winter, but I don't see any other apparent features (mantle shade aside) that are suggestive of henei - would be interested in other comments though.

It is a very hard job (an almost impossible one, I would say) to ID in the field Common Gull subspecies...

Cheers, couldn't find any better pics!

James

WelshS is right that this bird is a 2nd winter - note that the white primary tips are very reduced compared to an adult - and right to advise caution in the judgement of grey tones. While the primary projection at first glance looks encouraging for heinei, I think that that is due to the bird raising its tertials which makes the primaries look longer.

As Cristian points out, the field identification of this subspecies is thought to be near impossible. The best bet seems to be to find a colour-ringed individual - or get some biometrics on a bird in the hand. If you look at the limited images of heinei on the web, you will note that they don't look very (or any) different from canus! Even in the hand I get the impression that only the largest birds would be identifiable out of range - there is a cline between the two subspecies with many intermediate birds in the area of overlap.

That said, I have been looking quite closely at the variation in Common Gulls in Edinburgh in recent weeks. If you are interested there are various posts on my blog here.

Geoff

Supposing that the usual subspecies in Romania is heinei, you can also see some pics taken in Bucharest here:
http://www.talk.gull-research.org/viewtopic.php?f=7&t=3
http://www.talk.gull-research.org/viewtopic.php?f=24&t=195
http://www.talk.gull-research.org/viewtopic.php?f=24&t=181