Tuesday, December 4, 2018

A Frosty Gulf

Last week was one to forget, seven days of wind and rain with no birding. But now on Tuesday morning it was time to make amends with a much needed visit to Gulf Lane for Project Linnet. 

A quick check on Monday evening with on-line DemOn revealed a catch total of 470 Linnets in the three winters to date. The early winter is disappointing so far with a lack of Linnets on site, the reasons as mentioned in a previous post of 22 November- “an abundance of natural food that Linnets and other species have exploited, hence their lateness at arriving at Gulf Lane to a field of bird seed mix, one that could never match their natural diet.” 

It was a cold, frosty start this morning, 0730 and setting nets in the darkness to await the Linnets that roost fairly close by and soon after dawn arrive in groups for a morning feed. Our best count of the mobile Linnets this morning was 160+, a fair number, but as yet a good deal below recent winter counts of 400+. 

Andy in the dark 

Frosty Start 

Despite the lack of numbers we are still keen to catch more and explore the theory that many of our locally wintering Linnets are of Scottish origin and from the slightly larger and darker sub-species Linaria cannabina autochthona. We were given a boost for this idea on this morning by a first winter male with a wing length of 87mm, and two more with wing length of 84mm. The 87mm is at the top end of the range of published Linnet wing lengths, a data entry that provokes a query/potential error from the set parameters of DemOn, the online BTO database. 

Birds of Western Palearctic: Linnet Wing Length
Nominate race Linaria cannabina cannabina - Average ♂ = 80.8.  Range 78- 85 
Linaria cannabina autochtona (Scotland) Average ♂ = 80 - 82.  No range given 

Linnet - First Winter Male 

Such first winter birds carry their retained primary wing feathers, the ones they were was born with in the summer of 2018. The replacement feathers grown during the latter half of 2019 will increase the wing length by one or two millimetres. It would be good to recapture this or similarly sized Linnets in consecutive seasons but this is highly unlikely with minimal recapture rates for small passerines like the Linnet. 

We caught just 11 Linnets this morning, a slightly disappointing number given the 160 we saw, and while our project is not simply about numbers, the more we catch the better the information. 

Linnet

Birds have thousands of feathers and each one is subject to wear and tear that leads to moulting. Birders who understand the moult process can recognize how birds change their appearances and why those changes are a necessary and vital part of bird biology. Understanding the process can lead to easier identification no matter what stage a bird's plumage may be in. 

Moulting is the process of a bird shedding old, worn feathers to replace them with fresh plumage. A moult may be partial and replace just some of a bird's feathers or complete when all the feathers are replaced at once. The time it takes to complete a moult varies for different species, but may last as little as two weeks or much longer for larger birds. 

I found a video on the Internet that shows the typical sequence of moult in the wing of a passerine. It is quite instructive for anyone unsure or unaware of how and when birds replace their feathers.A passerine is a bird of the order Passeriformes, small songbirds which perch - more than half of all bird species. 


Another Bird Blog is back soon with more news, views and photos.

Linking this post to Anni's Blog,  Eileen's Saturday Blog and Stewart's World Bird Wednesday.

13 comments:

Jenn Jilks said...

That's really interesting! I'd never thought of it before!
http://bit.ly/2Sqq6vC

Rhodesia said...

I just hate the cold, I lived too many years in Africa me thinks. Frost means sit by the fire. I am delighted though that you braved the weather and gave us something interesting to read about. Keep warm Diane

Lowcarb team member said...

So often not a good time of year … but we do the best we can!

Thank you for getting out and about, and then letting us enjoy your blog posts from the comfort of our arm-chairs :)
I thank you (and Andy)

All the best Jan

David Gascoigne said...

Good afternoon Phil: A high quality post, as always. Moult is a fascinating topic and as you say a knowledge of it is often critical in determining the age of a bird. I am always cognizant of this phenomenon when shorebirds begin to arrive in the fall. Adults arrive first with their worn, bleached, sometimes scruffy, feathers followed by the young of the year in their crisp, bright first plumage, newly acquired before leaving the breeding grounds. The contrast is quite stark, and this is without having the bird in the hand. I continue to watch your progress with Linnets with great interest. I note that you are keeping Andy in the dark!

Angie said...

Phil - great information - and thanks for including the frosty fence picture - sharp!

Margaret Adamson said...

i think you mustbe having it colder where you live than us in N.I. No frost yet I think it is waiting until I leave this Saturday for Cape town!!!

Adam Jones said...

A fascinating read Phil, as ever. Glad the numbers are building again, just a shame you weren’t able to catch more on the day. They’re a great little bird.

betty-NZ said...

Interesting photos and post. Thanks for the information. I never thought much about bird feathers before :)

eileeninmd said...

Great post and information on the moulting. It look look very cold there. The birds look pretty sad looking during their moulting. Your Linnet is pretty.
Thank you for linking up and sharing your post. Happy Saturday, enjoy your weekend!

Anu said...

Hello. Interesting post. I have to watch that interesting video in this evening. Thank you.

italiafinlandia said...

It was interesting to watch your video. Nice to know.
All the best!

~Lavender Dreamer~ said...

You are very dedicated to do this work! Love this beautiful bird and the info is always interesting!

Anni said...

Excellent again Phil. I never cease to learn so much from you. The mounting video is a winner. Frost? In England? I just didn't realize the likelihood of that!! Too bad the numbers were low, but the next time out may be more.

You always give us so much pleasure and such a great variety of birds and wisdom no matter where you roam...for that I send along my thanks and appreciation for linking in with us at I'd Rather B Birdin. Have a beautiful week ahead & Happy Birding!

Related Posts with Thumbnails