Winter Bird-crops – Summary of Winter 2017-18

Compiled from reports produced by VAK for the respective landowners

Introduction

The Glastir Environmental Scheme supports the growing of an over-wintered cereal and brassica mix, either as a 1 Year or 2 Year Option. This crop provides a valuable feeding resource for finches, buntings and a number of common resident species in its first year (= year of sowing). It is largely the cereal seed within the mix that attracts the birds, and therefore in the second year there is little to interest wild birds apart from shelter.  At Glaslyn, Pennorth, a portion of a field was sown as a 2-Year Option, in April 2015 and April 2017.  At Penybryn Farms, Llangorse, a 1 Year Option bird-crop has been grown in each of the last four winters. The Llangorse crop rotates around the farm, and in 2017-18 was in a field adjacent to Cwrt-y-prior house and stables.  These crops have held the largest recorded winter Yellowhammer flocks in Wales for each of the four winters. In previous years, it has been noted that the numbers of birds using the crop tailed off quickly from mid-January. Both sites are relatively exposed, and weather conditions frequently limit ringing visits.

Maximum monthly bird-counts at Glaslyn (Pennorth), September 2017 – March 2018:

Species	September	October	November	December	January	February	March
Sparrowhawk		1
Pheasant	4
Woodpigeon	35		3
Skylark		12	3	3		6
Dunnock	2	2	3	5	2	3
Robin	3	3	3
Wren	2	1		5		3
Great Tit	1	1	1
Blue Tit	7	15	10	4	3	3
Long-tailed Tit		3
Blackbird		2	3	3	1	1
House Sparrow	4	42	15	20
Chaffinch		15	400	130	30	5	1
Brambling		1	10	2	1
Goldfinch		4		2
Linnet		80	5
Bullfinch						1
Reed Bunting	2	12	60	40	60	50	2
Yellowhammer	4	5	5	25	10
Nuthatch						1

Maximum monthly bird counts at Cwrt-y-prior (Llangorse), October 2017 - March 2018:

Species	October	November	December	January	February	March
Sparrowhawk			1
Pheasant			10			1
Stock Dove			13
Woodpigeon			20
Dunnock			6	5	6
Robin	1		5	3	2
Wren	3		10	3	2
Starling			350
Great Tit	2
Blue Tit	3		5	5
Goldcrest					2
Treecreeper			1
Chiffchaff	1
Blackbird			3		2
House Sparrow	35		50	30
Chaffinch	5	100	170	80		1
Brambling			1
Bullfinch			2
Reed Bunting	2		20	10	7
Yellowhammer	2	50	120	80

During the 2017 - 18 winter five ringing visits were made to the Glaslyn bird-crop, and three visits were made to the Cwrt-y-prior bird-crop.

Numbers in both tables below refer to birds ringed, with re-trapped birds in brackets.  At Glaslyn, all re-traps were originally ringed at the same site in either the current winter, or the 2015 - 16 winter.

Ringing dates and catches, Glaslyn (Pennorth)

Species	30/10/2017	17/11/2017	05/12/2017	28/12/2017	07/02/2018
Dunnock	1	1	1	7	(1)
Robin		2		2
Wren		4 (1)		1
Blue Tit	9	4	4	2	1
Blackbird			(1)	1
Song Thrush		1	1
House Sparrow				2
Chaffinch	3	23	10	31
Brambling		6		4
Reed Bunting	5	11	4	11	6 (1)
Yellowhammer	2			12
Nuthatch					1
TOTAL	20	52 (1)	20 (1)	73	8 (2)

Ringing dates and catches, Cwrt-y-prior (Llangorse)

Species	02/12/2017	20/12/2017	11/01/2018
Dunnock	4 (1)	4	2
Robin	2	1	1  (2)
Wren	2	1	3
Blue Tit	2	2	2
Treecreeper		1
Blackbird		3
House Sparrow	23	7	7 (2)
Chaffinch	3	3	13
Reed Bunting		4	1
Yellowhammer	20	15  (2)	16  (2)
TOTAL	56  (1)	41  (2)	45  (6)

Both Yellowhammer and Reed Bunting are the main targets for winter ringing on the birdcrops. Reed Bunting numbers were relatively low during the 2017 - 18 winter, but catches of Yellowhammer were good and consistent, the sexes and ages of those trapped are shown below:

Yellowhammer ages/sexes for Cwrt-y-prior (Llangorse)

Date of capture	Male	Female	First year	Adult
02/12/2017	7	13	18	2
20/12/2017	10	7	13	4
11/01/2018	7	11	18	0

Observations on birds that used the Glaslyn bird-crop (Pennorth), and ringing activity

• Spring Barley again provided a very good food source, especially for the finches and buntings (including more Yellowhammer than seen here in the 2015 - 16 crop).
•  Much of the seed supply gets used up, or becomes spoilt/rotten by mid-January. Woodpigeons and crows were less of a problem this winter, although there was evidence that large flocks of Starling (from the nightly Llangorse Lake roost) fed in the crop during October – December.
• The most severe winter weather from late-February occurred after the crop seed supply had been exhausted.
• The numbers of Chaffinches using the field between mid-November and mid-December was noteworthy, and reflected larger flocks of continental migrants in the UK than usual.
• The Brambling max. count and ringing catches (unusual in the Brecon area) were associated with this large arrival of Chaffinches from northern Europe.
• As a species, Reed Bunting appeared to hold in good numbers for longer, and later, through the winter. Quite why they prefer the Pennorth crop is a mystery, although may be related to it being a drier site surrounded by low, managed hedgerows, and relatively close to Llangorse Lake.  Since ringing started at the bird crop there have been six birds ringed at the Lake (from reedbed and scrub sites), and re-caught in the bird crop, one bird moved from crop to reedbed, and another moved from the Llangorse crop to the Pennorth crop.
•  It is noted again how few retraps occurred again in the 2017 - 18 winter (as per the 2015 - 16 winter). This suggests that there is a regular movement of new birds through the crops, rather than individuals staying for long periods.
• Song Thrushes were not counted/seen until they appear caught in a net. Most likely this is due to their secretive nature, and their preference for searching on the ground for slugs and snails under the brassica element of the crop.
• The Skylarks were only using the stubble part of the field, and not the bird-crop.

Observations on birds that used the Cwrt-y-prior bird-crop (Llangorse), and ringing activity

• A rather limited range of species were caught this year.
• Numbers of Chaffinch were high during the November/December period, a feature found at other sites (due to an increased number of migrant Chaffinches arriving from northern Europe).
• As with the Pennorth Reed Buntings, there have been some movements - since the group commenced ringing in the bird crops four birds moved from the Lake to the crop, one from the crop to the Lake, and from the Pennorth crop to the Llangorse crop.
• Ringing data for Yellowhammer is summarised above. Sex ratio was slightly in favour of females, and there was a predominance of juveniles in the catch. Why Yellowhammer has preferred the Llangorse bird-crops in each of the winters is unknown. There are reasonable breeding populations of Yellowhammer on the lower western slopes of Mynydd Troed and Cockitt Hill/Mynydd Llangorse, perhaps as many as 15 pairs. Could it be there is an element of local breeders in the wintering flock that are familiar with feeding sites, roosting locations, etc.? There is also a more varied mix of age in hedgerows too that may attract Yellowhammer, rather than box-shaped hedges or mature trees.  All recaptures of Yellowhammer have been at the Llangorse crops, from either a previous winter, or later in the same winter
• It was unfortunate that seed supply did not last through to March, a month that has in the past been productive for catches of both Reed Bunting and Yellowhammer. The departure of birds from late-January, and the stormy/snowy weather conditions thereafter, did not justify additional ringing visits.
• The continued lack of re-traps suggests that birds within the flocks have a high turnover rate with few staying for long periods. Alternatively (and this appears unlikely), there could be a good number of equivalent sites locally, offering similar good quality feeding in winter. In two of the last three winters there have been similar Glastir wildbird crops at Llangorse and Pennorth, but it has been found that there is little movement and exchange of birds between the two.

Acknowledgements:  The Llangorse Ringing Group thank the Roderick family and their staff for allowing access to Glaslyn, and for providing access routes via tractor wheelings around and through the crop.  The Group is also grateful to the Thomas family, Penybryn Farms  for similar permissions on the Llangorse crop, and to Alison Strawford (Cwrt-y-prior) for car-parking.

For Further reading on the bird crops see here:
Summary of Llangorse 2016/17: http://llangorseringing.blogspot.co.uk/2017/03/8th-session-at-llangorse-birdcrop.html