Saturday, 30 July 2016

Oxwich Marsh 30 July 2016: autumn migration begins

The day started very disappointingly. A moderate north-westerly wind (the worst direction for the marsh) of around 13 mph, was about 6 mph higher than forecast, and caused the nets to billow. The wind gradually died off over the course of the morning, and by midday it was almost perfect ringing weather (calm and mainly overcast).

Given the sub-optimal weather during the critical first few hours of the morning, the catch of 171 birds, of which 103 were migratory warblers, was pretty good. It broke down as follows:

Species
Ringed
Recaptured
Total
Great Spotted Woodpecker
0
1
1
Swallow
9
0
9
Meadow Pipit
1
0
1
Wren
1
0
1
Dunnock
2
1
3
Blackbird
0
2
2
Grasshopper Warbler
4
0
4
Sedge Warbler
33
3
36
Reed Warbler
20
7
27
Whitethroat
2
0
2
Garden Warbler
2
0
2
Blackcap
4
2
6
Chiffchaff
2
0
2
Willow Warbler
23
1
24
Blue Tit
3
0
3
Great Tit
1
7
8
Chaffinch
3
2
5
Greenfinch
15
0
15
Goldfinch
10
6
16
Siskin
1
1
2
Reed Bunting
0
2
2
Total:
136
35
171

The features of the catch were the first two garden warblers of the autumn, an excellent day total of four grasshopper warblers, an influx of sedge warblers, a few more swallows, and good numbers of sedge, reed and willow warbler.


Grasshopper warbler
Although it is likely that some of the warblers captured over recent weeks have not been local breeders, this was the first session during which we have trapped birds with significant fat and a species not likely to have bred locally. Single garden, grasshopper, willow and two sedge warblers were noted with fat scores of five (fat completely filling the tracheal pit and with a convex bulge), suggesting these birds were accumulating fat prior to migration. Garden warbler is a scarce breeding species and passage migrant in Gower, being more frequent in wooded valleys to the north and east of the Peninsula, and the two young birds captured are unlikely to have been of local provenance.
Garden warbler

Also notable was the capture of a very recently fledged meadow pipit, a bird that appeared likely to have left a nest close by (based on plumage characteristics). This is the first confirmation of meadow pipit breeding successfully on the marsh since we began ringing here in 2013. However it appears there are a few territories present.



Overhead there appeared to be siskins moving around. At approximately this time last year we noted a second brood of fledged juvenile siskin, but there has been no evidence of this in 2016 to date.

Thanks to this morning's team of Heather Coats, Wayne Morris, Emma Cole, Val Wilson, Hannah Meinertzhagen, Ben Rees, Lynn Watts, Sammy-Jo Pengelly and Terry Sullivan for company and assistance.

Further photos are below

Owain Gabb
30/07/2016
Grasshopper warbler

Whitethroat (Emma Cole)

The hoverfly Helophilus trivittatus (large tiger hoverfly)  was trapped (and subsequently released) from one of the nets

Sunday, 24 July 2016

Oxwich Marsh 23 July: some unexpected results

Conditions at the marsh were near perfect for ringing for the first few hours of the day. It was warm, overcast and virtually windless. A westerly breeze then gradually picked up, and the sun came out; the catch in the reedbed then dropped off, and we began to take the nets down around 10:30. 

The catch was as follows:

Species
New
Recaptured
Total
Sand Martin
1
0
1
Swallow
8
0
8
Wren
6
0
6
Dunnock
1
2
3
Robin
1
1
2
Cetti's Warbler
2
1
3
Sedge Warbler
11
2
13
Reed Warbler
23
6
29
Lesser Whitethroat
1
0
1
Whitethroat
1
0
1
Blackcap
2
0
2
Chiffchaff
4
0
4
Willow Warbler
7
0
7
Goldcrest
1
0
1
Blue Tit
3
0
3
Great Tit
5
8
13
Treecreeper
3
0
3
Chaffinch
2
3
5
Greenfinch
6
1
7
Goldfinch
18
3
21
Reed Bunting
7
0
7
Total
113
27
140

A sand martin (in the half light)
On arrival at the marsh it was apparent that a swallow roost was present very close to the main net ride. It then became a race against time to get the nets up ahead of the roost breaking up at dawn. We managed it, but most of the c. 200 birds flew away from the net line, and we only captured eight swallows and a sand martin. Still, an unexpected start.

As noted in Barry's blog post of yesterday, this was the first day when dispersal of birds through the marsh was noted. In addition to 29 reed warblers, the 13 sedge warblers, 7 willow warblers and lesser whitethroat all indicated that birds are moving around. The lesser whitethroat, a juvenile, was probably the bird of the day; we typically only capture a couple of birds a year (they are a fairly sparsely distributed local breeding species and do not breed close to the ringing site).




One of our three treecreepers

It was notable to catch three treecreepers in a session. All were recently fledged juveniles (as were the seven reed buntings and the two new Cetti's warblers captured). The continued dearth of blue tits does now suggest a very poor breeding season for them locally; we have caught 128 unique birds this year to date, while at the same point in 2015 we had caught 198. Of the 2016 birds only 25 have been juveniles compared to 87 (by 23 July) in 2015.


If you would like to understand what it takes to become a ringer and/or are interested in joining the Group, please leave your contact details in the comments box at the bottom and we will get back to you in due course.

Thanks to Heather Coats, Cedwyn Davies, Emma Cole and new prospective trainee Terry Sullivan for their company and assistance this morning

Owain Gabb
24/07/2016


A smart-looking young willow warbler


A dispersing sedge warbler

Our first lesser whitethroat of 2016

Lesser whitethroat (showing typical iris colour of young bird)

Cinnabar moth caterpillars on ragwort