SEPTEMBER 2008'S MYSTERY BIRD ANSWERS

So, hands up all those of you who hate gulls. Living rooms, kitchens, study's and the like all around the county are now complete with birders frantically stretching their hands aloft, straining to get the very last inch out of their limbs but lets face it, they offer undoubtedly the biggest challenge and the most complex identification puzzles of any species we can go out into our county and see on a regular basis, so why ignore them? 24 entrants chose to push themselves to their limits of identification with this beast and they should be commended on their bravery in offering an identification in the first place but what the hell is it...?

Mystery Bird 17

Firstly some background to this bird. Rather than being clear cut and identification complete, photos of this bird (infact these very photos here) were initially sent to me by email as the finder of it wanted to check his original identification, however, on seeing them it struck me that it was infact not what it was originally believed and was something completely different. That initial assessment was just a gut feeling, an opinion based on an overall 'feel' of the bird, delving deeper into a more thorough assessment, whilst eventually confirming the identification didn't always necessarily help such can be the complexity of these beasts and infact the finder also sought an opinion from two very experienced and widely acknowledged 'gullers' (one in the UK and one in the Netherlands) who fortunately also came to the same conclusion as myself. So, no moaning about it being 'easy for me' or that I wouldn't get it right either. Been there, done that ☺

So, lets look at the species offered as answer, Lesser Black-backed Gull (1 vote), Yellow-legged Gull (13 votes), Herring Gull (3 vote), Kumlien's Gull (1 vote), Caspian Gull (3 votes), American Herring Gull (2 votes) and Glaucous Gull (1 vote) and just to clear things up Caspian Gull (Larus cachinnans) is now a separate species from Yellow-legged Gull (Larus michahellis) which is in turn now a separate species from Herring Gull (Larus argentatus) as is American Herring Gull (Larus smithsonianus) now a separate species from Herring Gull (Larus argentatus)...phew! Also, as been said before, ageing of any gull should be your first step in identification so it was encouraging to see that many of you correctly identified the mystery bird as a 2nd summer (3rd calendar year bird), shame you don't get any points for that though! Please note that the explanations for each species below have been kept simple and I have refrained from delving 'too deep' into the murky world of larid identification, afterall I don't want you all to give up before you've even started.

For our first species, some confusion arose from the fact that our single Lesser Black-backed Gull entrant felt that the two right hand birds were probably the darker, Scandinavian race of Lesser Black-backed Gull (Larus graelsii intermedius) which would mean that mystery bird, which is clearly paler than the Herring Gull on the extreme left must be a British race Lesser Black-backed Gull (Larus graelsii graelsii). However, the head shape should be similar for both races of Lesser Black-backed Gull and our mystery bird clearly has a more angular head shape and it's mantle shade is still too pale even for a graelsii Lesser Black-backed Gull. Bright, direct sunlight can give grey tones on gulls a much paler appearance and confusion has arisen in the past from Lesser Black-backed Gulls in strong sunlight being mis-identified as Yellow-legged Gulls but these two right hand birds are clearly not dark enough for intermedius which would show little contrast between the grey mantle and wing coverts and the blackish primaries, so I'm afraid our mystery gull isn't a Lesser Black-back!

Glaucous Gull is easily eliminated thanks to our mystery gull's solidly dark black/brown primaries and Kumlien's Gull is also eliminated by the presence of the same feature and the fact that, amongst other features, neither of these species displays a mantle tone anywhere near that our mystery gull.

So, that only leaves us with the four 'old money' Herring Gulls and if they hadn't all been split into full species in their own right then this mystery bird would had been oh so much easier!

American Herring Gull is infact very similar to our very own argenteus Herring Gull on mantle tone and so the comparison between our mystery gull and the argenteus Herring on the very left of the photo clearly shows them to be very different with the mystery gull being much darker, dark enough to eliminate American Herring Gull from our potential suspects.

Caspian Gull has a similar mantle shade to our mystery bird but the legs look too short for that species (which usually looks very long legged) although we have to consider the way the bird is 'hunched up' but the head shape is wrong for Caspian, too obviously square looking with a very steep angular forehead and the course dark markings around the head, neck and breast are wrong for that species too. Nope, it's not a Caspian!

This leaves us with only Herring Gull and Yellow-legged Gull, of course Herring Gull encompasses two races, the British argenteus race and the Scandinavian argentatus race and with a mantle colour as dark as our mystery bird (utilising the comparison with the argenteus on the left of picture again) it could only be argentatus (confused yet?). So, argentatus Herring or Yellow-legged, both can be infact quite similar and on lone individuals without comparison argentatus Herring Gulls are often mis-identified as Yellow-legged Gull due to their similarly dark grey toned mantle and wings, but can that be what has happened here, afterall our mystery gull was taken in July in the western UK, a prime time for Yellow-legged Gulls but not for argentatus Herring which is a winter visitor to our shores and inland reservoirs? Let's look at what we've got. It's not a particularly big bird but that doesn't help us much owing to the size differences between males and females of either species, the mantle colour could fit either, there appears to be a good primary projection (beyond the tip of the tail), a good feature for Yellow-legged Gull but then again whereas argenteus Herring has a short primary projection, argentatus is longer, so back to square one (we should also be cautious of the camera angle potentially accentuating this feature)! The legs do look admittedly very short (so pro-argentatus) and the bill doesn't look obviously blunt ended or deep enough for Yellow-legged and overall seems to fit argentatus better, there also seems to be a little hint of pinkish at the base of the bill (particularly on the lower mandible) which Yellow-legged Gull shouldn't show but we're pushing it here on this image alone. The head shape however would seems to start to reveal this bird's true identity. It seems very square shaped and angular, lacking the almost bulbous, swollen forehead of Yellow-legged and seems quite small headed overall, to the experienced eye (and it's not always easy to explain why!) it just looks like an argentatus but it is those coarse dark markings around the head, neck and breast seem to offer us our conclusion as they are all wrong for Yellow-legged Gull which should be all together more pale headed with any head streaking confined to the area around the eye and crown (like earphones!), it just doesn't fit right with Yellow-legged Gull and that is because our mystery bird, as long-winded as it might have been to get to our final decision, is indeed an argentatus Herring Gull.

The fact is, that I specifically chose this gull as mystery bird number 17 to illustrate the potential pitfalls of identification, since it had already fooled some excellent gullers in their own right and in the hope that we might look more closely and not jump to 'every dark-mantled Herring Gull's a Yellow-legged', even if it would seem that an argentatus Herring Gull in July in the UK would be extremely unlikely. Yellow-legged Gulls are so much more than 'dark-mantled Herring Gulls' but their identification can be very difficult and confusing to the inexperienced (not to mention the experienced!) so look carefully the next time you think you have one, don't just get drawn in by the tone of the mantle, look at the structure of it's bill and head, overall jizz, any head markings, and most importantly, leg colour (of course) and if it flies, flaps or just raises/stretches it wings, the extent of the black on it's primaries. But that's one feature I'll leave to you to get your books out and read for yourselves.

Only four entrants managed to correctly identify this mystery bird correctly, Michel Rogg, Dean MacDonald, Rob and Sonia Adderley and Dave Broome, so give yourselves a pat on the back!

Above: Herring Gull (Larus argentatus argentatus), Dumfries and Galloway, July 2008 (Pete Berry)

Below: Yellow-legged Gulls from Pennington Flash and Heaton Park Reservoir for comparison (all by Ian McKerchar)

Mystery Bird 18

Our 24 entrants this month were split amongst six species for this mystery bird, although to be fair, 19 of those entrants got it spot on and managed the correct species but after the previous mystery bird's long-winded explanation (how many of you have just woken up having fallen face first fast asleep into the keyboard?) I'll keep this quick. Jay, Wigeon and Snipe were all offered as answers and had me initially scratching my head somewhat as to if those entrants were looking at the right bird (still not sure!), our mystery bird lacks Jay's overall pink plumage, it has a greyish streaked head and is streaked on the mantle, so it doesn't fit Jay; Wigeon (I can sort of see where they were coming from with this, but...) doesn't have a streaked mantle and isn't so strongly warm brown either and Snipe is a bird of contrasting dark brownish/black and bright yellowish stripes, quite unlike our mystery bird. No, it is none of those. Shorelark was another offering but it too lacks our mystery bird's strongly warm brown upperparts, also the white patch in the wing and I'd expect Shorelark's strong head pattern to be evident on this image if it was one. This leaves us with our remaining two suggestions of Linnet and Twite but quickly, Twite is again clearly never so strongly warm brown on the upperparts as our mystery bird and it's upperparts are always more strongly and obviously streaked anyway. So, Linnet it is!

Linnet, Irlam Moss, June 2008 (Ian McKerchar)

Only three entrants managed to correctly identify both species correctly in this, the round with perhaps the most difficult mystery bird to date, so they are to be especially commended. Well done indeed to Michel Rogg, Rob and Sonia Adderley and Dave Broome.

Of course this means that our long time leader Simon Johnson did indeed slip up this month and with that has allowed Rob and Sonia Adderley to within 1 point of him, so he cannot allow another point to go amiss (no more gulls this year you'll be happy to hear!). Either way he still remains our current leader, so on to the next round and all it may bring.