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.

Reprise

Saturday was spent watching for breaks in the rain, living in hope the forecast might change for the better; it did, so Will and I found ourselves at Out Rawcliffe again this morning, and hoping for a repeat of Thursday’s catch of 122 birds.

But we didn’t quite hit the same heights with today’s catch of 94 birds of 12 species, 93 new and a single recapture of a Chaffinch from recent weeks. New birds today, 48 Chaffinch, 29 Meadow Pipit, 3 Chiffchaff, 3 Blue Tit, 2 Goldcrest, 2 Coal Tit and singles of Great Tit, Goldfinch, Robin, Lesser Redpoll, Dunnock and Blackcap.

Chiffchaff
Goldcrest
Chaffinch – adult male
Lesser Redpoll

The throughput of Chaffinches from north to south was very marked today, with larger groups than of late and sometimes up to 10 or 12 individuals, which led to an overall count for the 6+ hour session of approximately 600 birds. The Meadow Pipit passage was slightly less than last Thursday with today’s count being 300+ birds, but again a mid-morning peak. There is a marked sexual difference in Meadow Pipits but one of today’s males was quite enormous, with a wing measurement of 90mm, significantly above the quoted range in Birds of the Western Palearctic (BWP). This bird just has to be of Icelandic origin.

We are now seamlessly into the swing of ageing Meadow Pipits, a process which is easier than determining their age in spring. However to accurately age any species it is essential to have a thorough knowledge of the moult and wear of those species’ feather tracts and a grasp of the general principles of ageing. If it is a species we don’t see in the hand very often a copy of “Svensson” or “Moult in Birds” are always to hand, books which give invaluable guidance. Both of the above mentioned books are actually invaluable to bird watchers who might want to spend time ageing species in the field through a telescope, but to bear in mind that some of the feather tracts or other features described may be invisible on a closed wing or tail.

”Svensson”
Moult in Birds

In the case of Meadow Pipits we have many years of experience with them to recognise the features of an adult’s complete post-breeding moult, or the partial moult of a juvenile bird where it replaces some only of its feathers. We also take into account the fact that in the north of their wide range an adult Meadow Pipit moult may take several days less than a typical UK Meadow Pipit, and in addition allow for the fact that Meadow Pipits may have two or more broods of young; the young birds could have been born anytime between the months of April/May and August, and depending upon their places of origin and date of birth, apparently identical juveniles may actually show quite differing amounts of feather wear and/or replacement.

The photographs below are from today, a recently fully moulted adult Meadow Pipit with the same age of feathers throughout the wing structure, and below that an image of a juvenile wing with a mix of recently grown adult type feathers and its retained juvenile “summer” feathers.

Meadow Pipit - adult
Meadow Pipit - juvenile

Once again our busy ringing session meant missing some of the visible migration, but we noted 37 Snipe, 20+ Skylark, 35+ Siskin in 3 separate groups, 20+ Lesser Redpoll, 3 Sparrowhawk, 180 + Swallows and 6 House Martin.

“Locals” included 2 more Sparrowhawks, 9 Buzzard, 2 Tawny Owl, 40+ Goldfinch, 20+ Linnet, 2 Kestrel, 3 Jay and 2 Great-spotted Woodpecker