Monday, October 3, 2016

YBW and Linnets

Yellow-browed Warblers seem to be everywhere again this autumn. Not to be left out of such excitement there was one calling loudly around the garden on Sunday afternoon. Several times I heard the loud, coal tit-like slurred call and then managed to locate the tiny warbler in the tall sycamore of a neighbour’s garden. The sycamore branches almost overhang my own garden in a couple of places so I’m not certain I can claim the YBW as a first for my garden list. Within a minute or two the bird had moved on, not to be heard or seen again that day or the next. 

 Yellow-browed Warbler- Photo credit: Hans Olofsson via / CC BY-NC-ND

Considering that the first Yellow-browed Warbler was only recorded in Britain in 1838, and that over the next 130 years only 300 of these Siberian sprites were seen on our shores, their now regular September appearances give birders food for thought as well as a reason to go searching for one of their own.

Yet the incredible migration strategy of these tiny warblers may indicate a more serious long-term climatic trend. By rights, each autumn Yellow-browed Warblers should head south east from their Siberian breeding grounds to winter in the warm tropical forests of Myanmar, Laos, Thailand, Vietnam and Cambodia. But over the past few decades, increasing numbers have been sighted across Britain and Western Europe, down to Spain and The Canary Islands during September and October.

This may be an indicator they are improving their survival rates by seeking out new wintering territories in Africa and close to their relatives the Chiffchaff and the Willow Warbler.

On Monday I met up with Andy and we headed to Cockerham to follow-up the permission to catch Linnets. As a ringing group in recent times we have caught less than twenty Linnets annually, such is the species’ decline and the reason that we wish to use this opportunity. We cut a single ride in the set-aside field much quicker than we imagined which left us time to have go at catching a few birds. Despite our upsetting their dining table the Linnets came back very quickly and although the sun shone on our single net set low in the field and the breeze was less than ideal, we managed to open our account with two Linnets, a first autumn male and a first autumn female. We both feel confident we can catch more Linnets in the coming weeks and therby collect important data on this declining farmland bird.

We had to remind ourselves how to sex Linnets in October when there are lots of similar looking juveniles/females and also when most males have lost their striking red and orange breast feathers. On a male the white on the inner parts of the 7th-9th primary feathers reaches the feather shaft itself or is less than 0.5mm in width to the shaft. On a female the same inner parts of the 7th-9th primary feathers never reaches the shaft itself and shows a darker zone, 0.5mm wide or more. In other words, the male has more white in the wing than a female, a feature that can often be picked up on Linnets in flight during the autumn. The difference can be seen below.

Linnet - female

Linnet- male

Linnet - male

Whilst ringing we noted many hundreds of Pink-footed Geese overhead, all heading south. In amongst the set-aside field we also saw a couple of Goldfinch and Tree Sparrows. A Kestrel circled around a couple of times and there was also a Sparrowhawk which made a single attempt to snatch a Linnet by flying into the set-aside crop, scattering the finches in all directions.

The Sparrowhawk failed but for sure it will be back. And will too for another look at those Linnets.

Linking today to Stewart's World Bird Wednesday.

10 comments:

Prunella Pepperpot said...

The little yellow brown warbler is lovely. Hopefully it will be back to pose for a photo!
Good luck netting the linnets. I always thought it was very sad when the farmers ripped out the local hedgerows. If only we could turn back the clock.
Have a great week.

David Gascoigne said...

Nice dissertation, Phil, and as you may imagine I was very interested in the sexing technique for the Linnets. Hope you mannge to catch a few more before the season is out.

Linda said...

Lovely photos, Phil. I had no idea how to tell the difference between a male and female linnet but, thanks to your photos, details and explanations, I do now.

Russell Jenkins said...

Phil, that Sparrowhawk header is just magnificent! I tried to understand your clear description in separating the sexes but I'm sure glad you kindly provided the image examples, which are just brilliant. Sadly, it seems many species are in decline.

Margaret Adamson said...

Lovley to see the YBw Phile and the 2 shots showing the difference in the Linnets wings

eileeninmd said...

Hello Phil, the warbler is a beauty! Great find!

Happy Tuesday, enjoy your day!

Andrew Fulton said...

A nice post Phil... thanks for the info

Firas said...

Beautiful close images. Liked them.
Cheers, Firasz

Breathtaking said...

Good morning Phil!:) I'm now sure that I saw a Yellow Browed Warbler yesterday. Like you I heard it's song, which for me was unfamiliar, and saw a little bird like this one perched in our peach tree. Thank you for the wing photos of the Linnet and the info, and good luck netting more Linnets.

Lowcarb team member said...

I really like the colouring of the little yellow brown warbler ...

Hope your week is going well

All the best Jan

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