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

Thursday, 18 August 2016

Oxwich Marsh 18 August: a Gower Rarity

An odd morning in some ways. Warm, still and close, with early fog rapidly lifting.Very few birds were present in the marsh (26 in four hours suggested a clear out the night before / a lack of influx), but what there was there was well worth the trip out.

Due to limited personnel we only put a small amount of net up. The pipit triangle and seven forty foot nets through the reed bed. The first bird of the day was a garden warbler, and an hour later we caught a second. These were numbers 8 and 9 of the year, a good total for a fairly irregularly recorded autumn passage migrant in Gower.

Willow tit (Keith Vaughton)
Having put the pipit nets up, and had a look at the South Pond, we were just walking back to the ringing field when we heard a vaguely familiar call. It took a few seconds to register that it was a willow tit (a less than annual species in Gower in recent years). We started to look for it. The bird was flitting around in some scrub. It called again, pausing in open view long enough to reveal a pale wing panel and fairly buff-looking flanks / underparts. 

Willow tit wing with fairly understated pale panel
As we were only about 50 m from the pipit nets, I made my way back and put on a willow tit tape. The bird instantly became alert and flitted through the scrub, moving towards the tape. We left for a few minutes, returning to find it in one of nets. Given the calls, views and attraction to the tape, separation from (the very similar) marsh tit was not really in doubt, but catching it potentially allowed conclusions to be drawn with regard to age and/or sex.

Back at the ringing table we made a close inspection of the bird, and measurements were taken. The wing and tail feathers were very fresh, there was no evidence of a re-feathering brood patch, but some tracts of body feathers were being moulted. Given that an adult willow tit would likely be in main moult in mid-August (typically main moult takes place between late July and early September), but that the flight feathers were very fresh and there was extensive pin on the body, it was determined as a a young bird in post-juvenile moult (age/moult code 3JP). A relatively understated wing panel is typical of young willow tits; adults have paler fringed inner secondaries and terials which makes the feature more obvious. The panel is visible in the photos.

The wing of the British subspecies of willow tit, kleinschmidti, typically measures 55-63 mm (marsh tit 59-71) (Svensson, 1992; Demongin, 2016). Ours, with a wing length of 59 mm was near the middle of the willow tit range but right at the bottom of that of marsh tit. Another feature that is considered useful in separating freshly-plumaged willow tit and marsh tit is that the 6th tail feather falls more than 4 mm short of the tip of the tail in willow tit (marsh tit tail feathers are usually less than 5 mm short of the tip). Our bird had a difference of 5 mm. Although marsh tit cannot be ruled out on these features, they are the shortest wing length and the longest tail difference recorded in marsh tit respectively, but typical of willow tit. 

Willow tit tail showing pale edges and indicating the length
difference between the central and outer feathers.
Demongin lists further features that are typical of willow tit. Some of these are rather subjective: the bill is more elongated than that of marsh tit; willow tit tends to lack a pale cutting edge (and if present this in on the lower mandible; the lack of a well-defined black bib, and whitish cheeks and sides of the neck are typical of willow tit (the latter are often grey-brown in marsh tit). The top photograph indicates that our bird showed all of these willow tit features.

Other interesting notes from Demongin concern iris colour, which gradually changes from dark brown in juveniles to light / rufous brown in adults, and pale edges to the tail feathers in juveniles. Our bird showed both a dark iris and pale edges to tail feathers, indicating a juvenile (see photos).

On release the bird flew approximately 50 m north-east to an area of scrub. It promptly started its nasal calling again.

The next net round produced two stonechats. The following round produced another, The only frustrations of the day were a kingfisher that bounced out of a net and a complete lack of migrant tree pipits in the nets despite a haul of sixteen a few days ago.

Many thanks to Heather Coats, Keith Vaughton and Ben Rees for company and assistance.

Owain Gabb
21 August 2016


Stonechat (Keith Vaughton)

Stonechat (Keith Vaughton)

Sunday, 14 August 2016

Oxwich Marsh 14 August: sixteen tree pipits!

A virtually windless and overcast morning provided ideal conditions for ringing. We put up a total of 960 feet of net in a series of lines through the reed bed and in reed bed edge habitat along with a pipit triangle in rushy pasture.

It was a steady morning. The settled weather during the preceding night may have resulted in some birds clearing out, but the mix of birds and the numbers of some species were excellent.

The catch was as follows:

Species
Ringed
Recaptured
Total
Snipe
1
0
1
House Martin
1
0
1
Tree Pipit
16
0
16
Wren
8
3
11
Blackbird
1
0
1
Grasshopper Warbler
1
0
1
Sedge Warbler
17
1
18
Reed Warbler
11
6
17
Whitethroat
2
0
2
Garden Warbler
5
0
5
Blackcap
1
0
1
Chiffchaff
2
0
2
Willow Warbler
41
3
44
Blue Tit
1
0
1
Reed Bunting
0
3
3
Total:
108
16
124

Tree pipit (Paul Aubrey)
The features of the catch were sixteen tree pipits (the best day for the site to date); single snipe, house martin and grasshopper warbler, five garden warblers, an excellent day total of 44 willow warblers (including a control) and the recapture of an aged reed bunting.

There was considerable passage of tree pipit overhead during the morning, with at least 25 birds noted. The first bird in the nets was captured approximately an hour after dawn, with numbers then increasing, and one mid-morning net round returning seven birds. The hind claw of the tree pipits was measured to confirm species (they have a shorter claw than meadow pipit). However, most were instantly recognisable as tree pipit based on plumage features. All were young of the year.

Snipe (Paul Aubrey)
The house martin was the third of the year and the grasshopper warbler the twelfth. The martin was in the lowest shelf of a forty foot net, which seemed unlikely!  More unlikely however was a snipe; the species is relatively scarce in Gower in August, and was assumedly foraging in mud caused by foot fall adjacent to one of the net rides.

Garden warbler is very much a mid to late August bird at the marsh, based on results from previous years (albeit we have captured a few birds in September). One of the five birds was aged as an adult, based on wear and bleaching of the flight feathers, with the others being pristine juveniles.
House martin (Emma Cole)
Willow warblers were everywhere, and it was good to secure our first control of the species. We will await the details with interest.


Finally, the reed bunting was ringed in August 2010, and was therefore at least six years of age. The brood patch was still feathering up. The head was very dark, superficially similar to a male, but with brown flecking and an incomplete off-white neck collar.

Thanks very much to this morning's team of Keith Vaughton, Wayne Morris, Paul Aubrey, Emma Cole, Darren Hicks and Sammy-Jo Pengelly.

Further photos are below.

Owain Gabb
14/08/2016

Garden warbler (Owain Gabb)


Great green bush cricket (female) (Paul Aubrey)
Larva of the sawfly Athalia scutellariae (thanks to Barry Stewart for the ID).
Whitethroat (Emma Cole)