Sunday, 22 September 2013

Oxwich Marsh 22 September

A good morning at Oxwich Marsh with 81 birds of 12 species caught in overcast, calm conditions.  In addition to resident species, reed warbler (5), chiffchaff (15), grasshopper warbler (1), blackcap (4) whitethroat (2) and swallow (23) were captured.  One of the whitethroats (below), was an adult, and showed an attractive hazel-coloured iris as well as white outer tail feathers (and other features indicating its age).  Both whitethroats were carrying significant fat (scores of 5 and 6 respectively with regard to the BWG system), as were a number of blackcaps and the grasshopper warbler (a young bird with a fat score of 6).

The migrant reed bed warblers seem to be on the wane, and there were no sedge warbler seen, heard or captured this morning.  Chiffchaff, in contrast, were relatively abundant in the scrub, but willow warbler were similarly noticeable by their absence, with a single bird heard calling during the morning. 

Swallows were captured over the main channel running through the site, over which a 'ladder' bridge has been laid.  All bar one was a juvenile.  Pictures are below:

Thanks to Charlie Sargent and Aaron Davies for an enjoyable session this morning.

Owain Gabb


Saturday, 14 September 2013

Meadow pipits but still no martins

Another beautiful day at Oxwich Marsh this morning.  Due to the very low wind speed, and overhead movements of pipits, wagtails and Hirundines (barn swallow and house martin) we supplemented the usual nets in the reedbed and scrub with a triangle of nets in the open field (surrounding a tape lure).

The martins showed very little interest in the tape, but we did catch seven meadow pipits.  Ageing meadow pipits (see pic opposite) is not straightforward if you don't catch them regularly, but before attempting this you firstly need to confirm the species.  Apart from general plumage characteristics, they were separated from tree pipit on the basis of the length of the hind claw (which should be between 10mm and 13mm in length in meadow pipit and is shorter in tree pipit [7-9mm]).  This was measured using calipers.  Age was then determined based on a number of factors, particularly the colouration of the edging of the greater coverts, on the basis of different generations of feathers in the wing (adult wing feathers should be of one generation following post-breeding moult), and the shape and size of the dark 'teeth' on the median coverts.  Juvenile flight feathers should also show more wear, which is a good supporting feature.
The photograph opposite shows the wing of a juvenile meadow pipit.  It can be seen that one of the tertials has been retained (this has an abraded edge and a very white tip), but the others replaced.  This bird also appeared to have moulted its two innermost greater coverts, which were fresh and edged yellow-brown, but not the remainder, which had far paler edges.

In total 51 birds of 14 species were trapped.  The number of re-trapped birds (those already ringed at the site and recaptured today) is shown in parenthesis:  meadow pipit 7 (0); reed warbler 9 (3); sedge warbler 6 (1); blackcap 4 (0); chiffchaff 5 (0); robin 1 (0); chaffinch 1 (0); blue tit 7 (2); wren 2 (2); dunnock 1 (0); song thrush 1 (0); bullfinch 5 (1); blackbird 1 (1); great tit 1 (1).
We are now pushing 500 new birds for the year at Oxwich Marsh, which has probably exceeded expectation.  Thanks to Heather Coates, Barry Stewart and Cedwyn Davies for an enjoyable morning.
Owain Gabb 14/09/13.

Saturday, 7 September 2013

Plenty of warblers, but no martins ...............

As the weather forecast had been poor right up until last night (when it changed completely), the ringing session at Oxwich Marsh this morning was far better than expected.  A light north-westerly wind wheeled gradually to the north and strengthened over the morning, but until around 10am the nets were relatively still, and the rain held off despite showers until dawn.

The decision to go to Oxwich was fully vindicated by the number of birds trapped.  In total 43 birds of 11 species were caught.  These were: reed warbler (20), sedge warbler (7), Cetti's warbler (2), chiffchaff (3), blackcap (1), whitethroat (1), blackbird (2), wren (3), blue tit (2), bullfinch (1) and robin (1).   

The catch was dominated by young of the year, with only one of the blue tits being more than 1 year old.  Many of the reed warblers had finished their post juvenile moult, and are likely to be feeding up prior to migration.  Only a few had significant fat deposits however. 

The young of some resident species, such as wren and bullfinch, in contrast, are less well progressed in terms of post-juvenile moult.  In fact, one juvenile bullfinch was still in entirely juvenile plumage, with a bare belly, and no sign of any replacement of body feathering.  It was good to catch two more Cetti's warblers: both were juveniles with fresh flight feathers but extensive moult of body feathers going on.

Attempts to catch some house martins (following several mixed flocks of swallows and martins across the site) were 'after the horse had bolted.'  By the time an additional net had been put up all hirundines seemed to have disappeared.  Visible migration was very limited overhead, with only meadow pipits and the odd pied and grey wagtail noted in addition to the swallows.

Thanks to Charlie Sargent, Keith Vaughton and Cedwyn Davies for a pleasant morning and a good session.

Owain Gabb 07/09/2013