Showing posts with label Linaria cannabina. Show all posts
Showing posts with label Linaria cannabina. Show all posts

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.

Friday, March 9, 2018

Back To The Linties

Linnets have hung around all winter at Gulf Lane but Friday morning and with a gentle breeze from the south east came the first opportunity for a month or more to catch a few. 

Earlier this week when I’d topped up the seed feed there’d been about 120 Linnets in the field, 8 or more Skylarks and 3 Stonechat dotted along the fence. 

I met Andy at 0700 and within ten minutes we had the usual configuration of nets ready for action. The Linnets appeared ravenous as they dived into the area of the food from the off. Well into March, the hungry month for birds, there’s not much of their natural food left so our seed mix is doing the job. 

We had a good catch of 23 Linnets but failed to catch a Skylark; despite two Skylarks being in the net, they both escaped before we laid a hand upon them. The Skylark is the Harrier Jump Jet of the bird world in being able to rise vertically from a standing start, even when partially enveloped by a mist net. 

Skylark

Our catch of 23 Linnets comprised 8 first winter females, 2 adult females, 8 first winter males and 5 adult males. This brought our running total of new Linnets ringed during the Winter of 2017/18 to 237 individuals.

For only the second time at this site and with almost 450 Linnets behind us in two winters, we had only our second recapture – S800285 was ringed here on 2/11/2017 and recaptured today, but not in the intervening period. 

A glance at the coffee stained field sheet from today shows a few large males with wing lengths of 83mm. This was  surpassed by the very last adult male caught at 0930 with a whopping measurement and double checked via Andy as 87mm. Almost certainly this male will be from the Scottish and slightly larger sub species of Linnet, Linaria cannabina autochthona. By the way, and for those who collect such trivia, the old Scottish name for a Linnet is “lintie”. 

Today's Field Sheet

Linnet

"Lintie"

And now to work for the next hour or so in transferring the data for those 23 birds into the new BTO online database DemOn. 

DemOn - BTO

I knew that 87mm was a big one. DemOn gave me a validation warning.

"Wing-length queried as outside normal range of species – max 86mm"

"Validation warnings occurred when submitting the record. Please check the warnings, and click continue to save the record anyway. Please enter a comment for any warnings that require one before continuing. To go back and edit the record, click 'Cancel' ". 

A ringer’s work is never done but back soon with more news, views and photos.

Linking today to World Bird WednesdayEileen's Blog and Anni's Blog.


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