Saturday, 27 August 2016

Oxwich Marsh 23-27 August:swallows, pipits, warblers and a redstart

A spell of settled, overcast weather allowed us to get a few sessions in towards the end of August. Although the conditions were perfect for mist netting, being cloudy with very low wind speed, the number of  migrant warblers (other than willow warbler) in the reed bed appeared low throughout the period, presumably as overnight conditions enabled birds to move through quickly on their migration south. They did allow us to target diurnal migrants, however, particularly tree pipit, for which Oxwich is proving an excellent site.

Over the five days we completed one evening swallow roost and three standard ringing sessions. The number of personnel available was limited, and we stuck to lines of nets in the reed bed and in fen habitats around the edge of it. The combined catch of 402 birds broke down as follows:

Species
Ringed
Recaptured
Total
Great Spotted Woodpecker
0
1
1
Sand Martin
3
0
3
Swallow
183
0
183
Tree Pipit
19
0
19
Wren
4
2
6
Dunnock
2
3
5
Robin
3
0
3
Redstart
1
0
1
Stonechat
4
0
4
Cetti's Warbler
1
2
3
Grasshopper Warbler
1
0
1
Sedge Warbler
16
3
19
Reed Warbler
28
4
32
Whitethroat
8
0
8
Garden Warbler
4
0
4
Blackcap
2
0
2
Chiffchaff
11
0
11
Willow Warbler
33
0
33
Goldcrest
1
0
1
Blue Tit
14
4
18
Great Tit
2
8
10
Chaffinch
3
1
4
Greenfinch
25
0
25
Goldfinch
4
0
4
Siskin
0
1
1
Reed Bunting
1
0
1
Total:
373
29
402

The highlights of the period were the relatively large number of swallows captured (mostly during the roost session but with birds on all days), 19 tree pipits, grasshopper (1) and garden warblers (2) (bringing the year total to 13 for both), the second redstart to be caught at the marsh since we began ringing at the site in 2013, and continued steady numbers of reed, sedge and willow warblers. There was no sign of the willow tit captured during the previous session (18 August).

Of the 183 swallows only seven were adults, and we captured only a small proportion of the roost. The number of roosting birds in the marsh was difficult to assess, but well in excess of 500 were present, and the number of sand martins that we captured did not appear representative of their abundance within the roost.

Tree pipit passage varied considerably daily (and hourly over the course of each morning). Although some pipits will come straight in to a tape, we found (as usual) that they will often be drawn into a general area in small flocks (paying passing attention to a tape), and frequently as many are captured in nets running through marshy grassland / rush pasture with scatted scrub within a couple of hundred metres of a tape as they are in close proximity to it. Our total of 35 birds now exceeds the number captured in Wales in 2015 (23). Ageing them with confidence remains challenging, albeit young birds often appear to show wear in the tail or (sometimes) visible moult limits in the tertials and lesser / median coverts. Adults have more uniformity in the coverts and pristine, and apparently more rounded tail feathers.

It has been a record breaking year for grasshopper warbler at Oxwich, and we would hope there are more to come. The thirteen birds to date exceeds the eleven of 2015, and there is still time to capture the species in September. Peak passage of garden warbler appears to be in mid to late August at the local level, however, and it is unlikely we will capture too many more now in 2016. 2015 was a poor year for the species at the marsh, mainly due (in all likelihood) to bad weather precluding sessions towards the end of August.

Redstart (Keith Vaughton)
The redstart, a young male, was in post juvenile moult.  A smart bird nevertheless. Pictures are above and below

Redstart (Keith Vaughton)
Thanks to all of those who made it along to the various sessions: Heather Coats, Keith Vaughton, Wayne Morris, Emma Cole and Val Wilson.

Further Photos are below

Owain Gabb
27/08/2016

Common hawker (female) successfully extracted from the net.
Yellow belle (moth) attracted to the ringing table light during the swallow session. Other species attracted included antler moth.and the micro ringed china mark. A beautiful china mark was seen during one of the daytime sessions.

L-R Heather, Keith and Emma processing some early swallows

Tree pipits. You can get an impression of the stouter bill and the short hind claw (a couple of the features that distinguish the species from meadow pipit) here. (Photo Emma Cole)


Grasshopper warbler 13 of the year

Tree pipit. This photo shows the white belly and lack of extensive streaking typical of the species

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