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)


Wednesday, 10 August 2016

CES 10 at WWT 5 August 2016

Low numbers again this session however of the 16 birds, 12 were juveniles and we caught 11 species. There was a tit flock and several Goldfinches flying around but we caught only 3 tits and 1 Goldfinch, the second this year after 2 years without any.

Species
Juveniles
New adults
Re-trapped adults
Total
Chiff chaff
2
0
0
2
Wren
3
0
1
4
Robin
1
0
0
1
Song thrush
1
0
0
1
Bullfinch
1
1
0
2
Long tailed tit
1
0
0
1
Goldfinch
0
1
0
1
Blackcap
1
0
0
1
Dunnock
1
0
0
1
Great tit
1
0
0
1
Blue tit
0
1
0
1
Total
12
3
1
16

Thanks to Paul Aubrey, Phil Mead and Dan Rouse for help this morning and to Sammy-jo Pengelly for helping to set up before going to work.


Heather Coats

Tuesday, 9 August 2016

Oxwich Marsh: early August warblers and hirundines

A couple of sessions in short periods of settled weather at the start of August have proved reasonably productive. The first, on Saturday 6 August saw us deploy a total of 840 feet of net, predominantly in the reed bed and nearby rushy ground. The second was a roost visit for swallows, and we limited ourselves to a line of nets along a bund through the marsh (total length 280 feet).

The total catch over the two visits was as follows:

Species
Ringed
Recaptured
Total
Sand Martin
1
0
1
Swallow
107
1
108
House Martin
1
0
1
Wren
3
0
3
Robin
1
2
3
Song Thrush
1
1
2
Grasshopper Warbler
1
0
1
Sedge Warbler
13
4
17
Reed Warbler
18
8
26
Whitethroat
4
0
4
Blackcap
4
1
5
Chiffchaff
6
0
6
Willow Warbler
7
3
10
Blue Tit
0
1
1
Chaffinch
1
0
1
Greenfinch
1
0
1
Siskin
1
0
1
Reed Bunting
5
4
9
Total:
175
25
200

Whitethroat
Swallows have been roosting in the marsh for some time (a roost began to build in mid-July), but this was the first time we have managed to get an evening session in. The catch was a slightly under par 105 birds, with singles of both sand martin (after dusk) and house martin (before dusk), and a few other odds and sods, including two willow warblers and single sedge and reed warblers.

The swallows were mainly juveniles. Only four adults were noted among them. We caught a few birds prior to dusk, which were released following processing, and over-nighted the remainder in purpose made boxes. The house martin was a bonus. It is only the third we have caught since February 2013.

The highlights of Saturday's catch were the eleventh grasshopper warbler of the year, steady numbers of reed and sedge warbler, a few whitethroat and siskin number 150 of the year (a record for the site by some distance). Some overhead movement of siskin was noted, which may indicate dispersal following breeding.

We also noted a reed bunting that resulted in some discussion with regard to sexing.
Reed bunting (in main moult)
Back of reed bunting showing white neck collar
Brood patch of reed bunting (the feathers have been gently blown to reveal the brood patch in this photo)
The reasons for this may be clear from the photos above. Photos 1 and 2 might suggest a male: the bird is scruffy as in main moult, but has a predominantly black head (albeit with some brown flecking) and a marked white collar. The third photo is of its brood patch. This was very well defined and wrinkled, suggesting recent engorgement (a female characteristic). The bird also had a short wing (74 mm), which also suggests a female. We tend to handle over 150 reed buntings a year at Oxwich, but don't often see a bird showing such a confusing set of features. However on the basis of the brood patch we concluded it could only be a female. Any comments with regard to experience of similar birds would be useful (thanks to Jerry Lewis for some very useful notes via email).

Thanks to all who attended one or more of the two sessions: Heather Coats, Keith Vaughton, Cedwyn Davies, Emma Cole, Val Wilson and Lynn Watts.

Owain Gabb
09/08/2016

Swallow on overhead line (Keith Vaughton)
[we didn't manage a decent shot of a bird during the session]

View towards the marsh at dusk (Emma Cole)