Tuesday, 7 April 2015

Oxwich Marsh 6 April 2015: news of controls

A very pleasant morning at Oxwich.  The skies were open and there was a barely discernible northerly breeze.  We put nets in the scrub around the feeders (200 feet), in the fen meadow (180 feet) and in a new net ride through semi-natural woodland and rhododendron scrub near one of the main channels through the marsh.  Only the feeder nets proved fruitful.
 
The catch was more diverse than in recent weeks, and we caught our first sub-Saharan migrant of the year (willow warbler).  The breakdown was as follows:

Species New Re-trapped Total
Wren 0 1 1
Dunnock 0 3 3
Robin 0 2 2
Blackbird 0 2 2
Cetti's Warbler 0 2 2
Chiffchaff 1 1 2
Willow Warbler 1 0 1
Blue Tit 5 1 6
Great Tit 0 8 8
Magpie 1 0 1
Chaffinch 2 2 4
Greenfinch 1 0 1
Goldfinch 5 1 6
Siskin 0 1 1
Reed Bunting 0 2 2
Total: 16 26 42

Of particular interest were the willow warbler , a re-trap chiffchaff (ringed on the marsh in September 2014 and either now on passage or back to breed [no brood patch or cloacal protruberance was apparent]) and a magpie.  We have trapped one magpie a year for the past three years.  Beautiful and feisty birds in the hand, they can be aged based on the shape and pattern of the first and second (pattern only applies) primaries.
 
We also controlled a siskin.  This bird had been initially ringed in Minehead, Somerset in 2012, and was also captured at the marsh in June 2014, so we already knew some of its history.  It will be interesting to see if the siskin numbers now start to build, as they did in 2014.  There is no evidence of it at present. 
 
The two Cetti's warblers were re-traps from 2014.  More interesting news recently received from the BTO, however, concerned a Cetti's warbler initially ringed at Magor Marsh, Monmouthshire in July 2012 and re-trapped at Oxwich in November 2014.  Clearly Cetti's warblers disperse (as is demonstrated by the continued extension of their range in the UK), but to re-trap a bird that has moved almost 100km since ringing is great.

So, how are the results from 2015 so far looking in comparison to the same period in 2014?  The table below provides a breakdown of unique birds for the period 1 Jan to 6 April for the respective years.

Species 2015 2014
Jack Snipe 1
 0
Snipe 2
 0
Green Woodpecker 1
 0
Great Spotted Woodpecker 1 2
Wren 8 5
Dunnock 16 8
Robin 15 4
Stonechat
 0
2
Blackbird 2
 0
Song Thrush 1
 0
Cetti's Warbler 2 2
Chiffchaff 5 3
Willow Warbler 1
 0
Goldcrest 5 3
Long-tailed Tit 9
 0
Blue Tit 113 113
Great Tit 37 29
Treecreeper 1
 0
Magpie 1
 0
Chaffinch 78 29
Greenfinch 88 108
Goldfinch 120 129
Siskin 2 11
Lesser Redpoll 1
 0
Bullfinch 8 4
Reed Bunting 25 70
Total 543 522

Any comparison between years must be very cautious.  We have put up more net in 2015 than we did last year (although returns from extra nets have been limited), have visited the site more regularly, and sessions have varied a little in length.  Weather plays a massive part in determining the size of catches on any given day.  We have had permanent feeders in place since 2013 (albeit these are moved around within the site / rides), but another significant difference is there has been no ground-feeding in 2015.  Pheasants have taken up residence around the feeders and have been hoovering up all spilt fragments of seed, so ground-feeding has been pointless.
 
Comparisons are therefore limited and qualified.  The most notable difference has been is in the number of reed buntings trapped.  This may relate directly to the lack of ground feeding.  Interestingly, chaffinch numbers are notably higher in 2015 than the equivalent months of 2014, however, and this bird also typically forages on the ground.  Overall, the number of birds per session is lower in 2015 than in 2014.  By this time in 2014 we had only completed 9 sessions (58 unique birds / session), whereas we have completed 14 to date in 2015 (39 unique birds / session).  So the higher number of birds relates to extra effort, not to any evidence that there are more birds in the marsh.
 
Many thanks to Heather Coats, Charlie Sargent, Keith Vaughton, Darren Hicks and Valerie Wilson for company and assistance this morning.
 
Some pictures of birds from the session are below.
 
Owain Gabb
07/04/2015
 
 
Control Siskin (Owain Gabb)

The first willow warbler of 2015 (Charlie Sargent)

Magpie (Charlie Sargent)
 

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