Saturday, 26 October 2013

Oxwich Marsh 26 October 2013

A break in the weather, with the south-westerly winds dropping slightly and the rain holding off, allowed a relatively short session at Oxwich this morning.  The wind did pick up after a couple of hours, and the catch was limited by both the duration of the session and the fact that the nets were seldom particularly still.  After the nets were taken down we did some much needed net ride maintenance and planning for the winter.  This included cutting out a couple of new rides using a brushcutter, and trimming the vegetation around the winter feeding station.  The main target for the winter will be reed buntings, for which there is a long data set for the site.
In total 30 birds were caught this morning.  The catch was as follows: blackcap (1); goldcrest (2); Cetti's warbler (1); reed bunting (1); robin (2); (winter) wren (4); blue tit (10), long-tailed tit (5); blackbird (2); dunnock (1); song thrush (1).  Three of the five long-tailed tits, a blackbird, a robin and two of the blue tits were recaptures from previous sessions.  The highlights were the Cetti's warbler and the blackcap, which may have been an immigrant or a late passage migrant.  It was not carrying any fat, so the logical conclusion might be that the bird is likely to stay for the winter.  A picture of one of the goldcrests is below.

As it seems likely that we have recorded the last of our summer visitors, a summary of captures of these species ('new birds' as opposed to retraps) is included below:
Barn swallow - 23
Grasshopper warbler - 2
Sedge warbler - 61
Reed warbler - 112
Whitethroat - 17
Blackcap - 51
Chiffchaff - 41
Willow warbler - 22

The timing of the captures of the reed and sedge warblers seems to bear out conclusions drawn in the field i.e. that the number of reed warbler territories in the marsh was relatively low (individual birds could be clearly heard singing around the reedbed - there was no wall of sound) and that very few sedge warblers bred locally.  Only 2 sedge warblers and 5 reed warblers were caught prior to July, and most birds of both species were trapped in August and September, when they are likely to have occurred in the marsh while on passage. Notwithstanding this, fledged birds caught in July did clearly indicate that both species bred on site.  The two grasshopper warblers were both young of the year, but there was no indication from field observations that breeding occurred in the marsh (and one of the records was relatively late in local terms). 
Totals of resident species will be reported at the end of the year.  However 9 new Cetti's warblers have been trapped to date in 2013, which is of local interest.  It is hoped that the current tally of 25 new reed buntings will be substantially increased by Christmas, and that there is a similar increase in goldcrest numbers.  Recent captures of roving tit flocks have resulted in blue tit overtaking reed warbler as the most regularly trapped species in 2013 (the tally of new blue tits currently stands at 121). 
By the end of the session 669 new birds had been trapped at the marsh in 2013, and 789 birds if retraps are included.
Thanks to Cedwyn Davies and Charlie Sargent for company this morning, and to Charlie for the loan of his brushcutter.

Owain Gabb

Saturday, 19 October 2013

Oxwich Marsh 19 October 2013

Unsettled weather and a forecast of strong south-westerly winds in the build up to the weekend did not inspire confidence that a ringing session would be possible, but in the event the weather was relatively mild. 

A total catch of 56 birds comprised: 4 goldcrests, 3 reed buntings, 10 (3) wrens, 2 (1) blackbirds, 1 robin, 24 blue tits, 8 long-tailed tits, 2 great tits and a Cetti's warbler.  Brackets indicate retrapped birds.

The highlight was the Cetti's warbler.  The species can usually be sexed on the basis of wing length and weight, as the male is a larger, heavier bird than the female, and there is limited between-sex overlap in these measurements.  The bird we trapped was a female, with a wing length of 58mm and a weight of 11.4 grams.  A picture is below. 


The feature of the session was the lack of lingering breeding migrants, and the catch was 'wintery' in character.  Tit flocks were moving through the reed bed - blue tits and wrens were doing their best to make extraction difficult - and overhead redwing and siskin were heard and seen moving west.  There were no flocks of goldcrests heard or trapped (the birds caught were all singletons), and the chiffchaffs and blackcaps of recent weeks appeared to have moved on.

The main ageing challenges to wrestle with were therefore the great tits (none of which proved particularly difficult - as the immatures had retained obvious juvenile alula feathers), wrens (where we considered recent research on spot patterns as well as looking for old greater coverts and other features) and reed buntings (all of which were fairly obvious 1st winter birds).  The blue tits and long-tailed tits were far easier to assign to an age class: first winter blue tits show clear moult limits in the wing (often retaining some unmoulted greater coverts or alula feathers but always their primary coverts - adults have a wing that is uniform blue in colour); adult and juvenile long-tailed tits both undergo a full moult of flight feathers, making ageing them in the autumn impossible (BTO age code 2).  Long-tailed tits are always a pleasant bird to capture.  A photograph is below.
Hopefully next week will bring a few winter immigrants, late autumn migrants on their way south or perhaps a local scarcity to provide a bit of a technical challenge and reward the effort over the spring and summer.
Thanks to Cedwyn Davies, Charlie Sargent and Aaron Davies for coming along.
Owain Gabb

Tuesday, 15 October 2013

A Visit to the Vale

Heather, Charlie and I joined Chris at Ty'n-y-Caeau near Monknash in the Vale of Glamorgan. We supplemented our regular seventy-eight metres of nets along the hedgerow with a further thirty-nine metres in the corner of the field.
There were large flocks of finches feeding in the seed crop and feasting on the abundance of berries in the hedgerow and a number of swallows were observed flying low over the field in a south-easterly direction.


Meadow Pipit

The early catches tailed off after 10:00 a.m. yet in spite of the slight breeze and rather bright conditions we totalled fifty-two birds of ten species - 14 Goldfinches, 13 Greenfinches, 9 Linnets, 5 Yellowhammers, 4 Blackbirds, 2 Reed Buntings, 2 Meadow Pipits, 1 Chaffinch, 1 House Sparrow and 1 Song Thrush. 

Saturday, 12 October 2013

Oxwich Marsh 12 October

The weather forecast for the weekend had been changeable for days, and the main concern was that the north-easterly wind would be too strong to allow a session to be held or that it would seriously limit the catch.  In the event, it was relatively calm first thing, and the wind only picked up gradually over the morning.

Being mid October, there was always the feeling that we could catch something out of the ordinary.  We did, but it was not the eastern vagrant that we might have hoped for!  Instead, a couple of magpies got themselves tangled up in an extra net put up near the on site wood store.  Despite their abundance, they are normally too clever to fly into nets, and even when they do so, they tend to get out pretty quickly.  One duly escaped, but the other was successfully extracted.

In the hand, the ageing of magpies is based on the amount of black on the first and second primaries, with adults having a thinner black fringe on both, and the shape of primary 1.  Our bird was an adult, with the first primary being far more clear cut (in terms of pattern when ageing) than the second.  A stunning bird to look at closely. 

The catch amounted to 28 birds: song thrush 1; (winter) wren 7; robin 3; Cetti's warbler 2; great tit 1; goldcrest 6; chiffchaff 4; magpie 1; blackbird 1; blackcap 1; and, dunnock 1.

Thanks to Cedwyn Davies, Heather Coates, Aaron Davies and Keith Vaughton for another enjoyable morning.

Owain Gabb 12/10/13