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Showing posts with label icelandic black-tailed godwit. Show all posts
Showing posts with label icelandic black-tailed godwit. Show all posts

Sunday, 17 September 2017

Black-tailed Godwits

As promised a few posts back...

There are three sub species of Black-tailed Godwit Limosa limosa in the world. L. l. melanuroides, which breeds in eastern Russia, Siberia, China and Mongolia, has never been recorded in the UK so we can forget about that one, leaving us with these two...

The Icelandic Black-tailed Godwit (L. l. islandica) breeds mostly in Iceland, but also the Faeroe Islands along with a few pairs in Scotland. The majority winter in the UK, Ireland, France and Holland.

The small number of Continental or European Black-tailed Godwit (L. l. limosa) that breed in the UK (East Anglia) are at the western limit of their breeding range, with most breeding in western and central Europe to central Asia and west Russia. They winter around the Mediterranean and as far south as the west coast of North Africa, mostly Senegal.

So to summarise the above information, it would seem that islandica is an abundant winter visitor to the UK, whereas limosa is a very rare breeding bird and probably a fairly scarce passage migrant. And this is what the case seems to be on the Axe Estuary, through my observations and the on going Black-tailed Godwit colour-ringing project undertaken by the Axe Estuary Ringing Group. In fact I can't say I've ever seen/noticed a limosa here before.

Separating the two sub species is far from easy though, especially in winter plumage when on plumage they are identical.  Spring birds in breeding plumage are do-able, as are fresh autumn juveniles, and this is why I have been paying extra attention to our Black-tailed Godwit flocks this autumn as they've contained a high proportion of juvenile birds. Everything I've seen though has  looked fine for islandica, well until last Saturday morning...

A small flock (c12 birds) of juvenile islandicas have been feeding on Colyford Common at high tide over the past couple of weeks, but last Saturday morning (9th Sept) one bird really stood out and stood up! Bingo, surely my first limosa...

Juvenile/first-winter L. l. limosa on the left and juvenile  L. l. islandica on the right


The structural differences are pretty striking in the above photo. Longer necked, bigger headed, longer billed with a broader bill base and longer legged (noticeably the tibia).

Sadly the L. l. limosa at the back is out of focus in this shot


Check out the bill size difference!

L. l. limosa at the front


The above photo shows the neck difference nicely. All the islandica in the flock lacked any sort of neck bulge when they held their heads tight to their body, whereas the limosa always showed a noticeable bulge along the lower edge of the neck. Presumably this is simply down to the fact it's a larger bird with a longer neck?

L. l. limosa at the front


Looking at the actual plumage of the bird, I'm not sure how useful this is as there was so much variation in moult and wear within all the Godwits in this group. But I'm sure it's not a coincidence this was the palest and blandest bird in the flock, lacking any orange tones to the head, neck or mantle - just a buff wash. This fits well with the literature for the limosa as they are far less colourful as juveniles than the often almost bright orange islandica. Just a pity it wasn't a month earlier though when they'd all be in much fresher plumage.

It's also worth mentioning that when the flock took to the air, the size difference was just as notable in flight. It was always easy to see which one the limosa was even if you couldn't see any plumage features.

Because all I've got for sub species specific identification of this bird is structural differences, and no real plumage traits, I reckon that means I can do no more with it that write this blog post. This limosa Black-tailed Godwit would (on paper) be the first record of this sub species for Devon, and for me to submit this as a county first I would need all the boxes ticked, not just a few. Annoying yes, but when it comes to bird ID I am strict. Oh well, at least I've got a blog post out of it!

If you're after your own limosa it's very important to remember that overall size and bill length varies between sexes (and maybe age?) in Godwits like most other wading birds, so be aware that islandica will show a variety of bill lengths and body sizes. As with many things, a direct comparison makes it so much easier so it's best to study Godwit flocks, lone birds will always be tricky unless they show a particularly striking plumage.

And here's some useful links on the subject:

Birding Frontiers
http://birdingfrontiers.com/2011/07/15/more-on-continental-black-tailed-godwits/

Northumberland & Tyneside Bird Club
http://www.ntbc.org.uk/wp-content/uploads/2013/06/Black-tailed-Godwits.pdf

Handbook of the birds of the world
http://www.hbw.com/species/black-tailed-godwit-limosa-limosa

Monday, 7 August 2017

Quick Update and Icelandic Blackwits

Only time for a short update. The last few and the next few days have been and will be a bit hectic for a variety of reasons. I have managed a bit of time out though which I'll summarise here...

A morning wander around Black Hole Marsh last Friday showed the bushes were the busiest they've been so far this autumn. The highlight was a cracking juv Lesser Whitethroat along the track to the Tower Hide, but the ten Willow Warblers were just as exciting to see...

Autumn Willow Warbler - hope I get to ring some soon!


The marsh itself revealed a Greenshank, c18 Dunlin and two Cattle Egrets.

Saturday gave me less than above, although three Green Sands showed well.  In the afternoon I saw my first settled Yellow Wagtail of the autumn (but my third of the season) on Seaton Marshes.

Green Sandpiper


And that's about all the bird news from me, although there has been a few other bits and bobs about. The six Goosander are still around, as are at least two Cattle Egret. And this afternoon Dad had a juv Little Ringed Plover on Black Hole which was new in.

Lastly I have been showing my (annual) love for juvenile Black-tailed Godwits on Twitter over the past few days. I saw my first on Wednesday 2nd which showed really well in front of Island Hide...

Juvenile Icelandic Black-tailed Godwit


This dull photo doesn't really do it justice. They are the most beautiful colour, with soft yet crisp plumage and amazing patterning on their scapulars and tertials.   Despite the gloomy weather, a nearby adult meant I was able to take a nice adult vs juv comparison shot...

Moulting adult Icelandic Black-tailed Godwit (left), juvenile Icelandic Black-tailed Godwit (right).


There are so many differences visible and I would happily go through them all...but that would be boring so I won't. All I will say is just look at how different they appear, the adult is a tatty worn looking bird, whereas the juvenile is so so fresh - you can just tell all those feathers are new.  Such smart birds.