Saturday, 23 April 2016

Oxwich Marsh 23 April 2016

A light northerly wind strengthened and gradually swung around to the south-east over the course of the morning.

We put up a total of 580 feet of net, the majority of which was along a bund through the reed bed. Prior to dawn at least three grasshopper warblers could be heard reeling, and it was clear that there were also a few sedge warblers in. Reed warblers were conspicuous by their absence, however.

The catch was made up as follows:

Species
New
Recaptured
Total
Sparrowhawk
1
0
1
Wren
0
1
1
Dunnock
0
2
2
Blackbird
0
2
2
Grasshopper Warbler
1
0
1
Sedge Warbler
2
1
3
Blackcap
3
0
3
Willow Warbler
2
0
2
Blue Tit
1
0
1
Great Tit
0
11
11
Chaffinch
2
1
3
Greenfinch
1
0
1
Goldfinch
25
9
34
Siskin
7
3
10
Reed Bunting
1
3
4
Total:
46
33
79


The features were a second calendar year male sparrowhawk (sexed on biometrics), the second grasshopper warbler and the first few sedge warblers of the year, and a total of 34 goldfinches, the majority of which were un-ringed suggesting there is some passage going on at present.

Sparrowhawk (Keith Vaughton)

A few points of interest from comparison of the year to date with the same period during the past two years are as follows:

  • We have done better for non-passerines than in 2015 or 2014, with two sparrowhawk, a water rail, five jack snipe and six common snipe captured to date. Numbers of great spotted woodpeckers (4) are consistent with previous years, but we have not captured a green woodpecker yet this year (and had done so by this time in 2015).
  • We are a little ahead of where we were at this point in the past two years with regard to sub-Saharan migrants. We captured one spring grasshopper warbler in 2015 and none in 2014 (and already have two this year), while our first sedge warblers are earlier than 2015 and we have captured more willow warblers than we had at this point last year. We had already captured our first reed warblers by this date in 2014, however. 
  • Greenfinch numbers (39 unique birds to date) are considerably down on this point in 2015 (by which time we had captured 98), which was, in turn, considerably down on 2014 (134). It will be interesting to see whether this indicates a decline in the population, as in 2015 considerable numbers of juvenile birds from July onwards counterbalanced far lower spring totals than were captured in 2014.
  • Larger numbers of siskin (115 birds unique to date as opposed to 7 in 2015 and 38 in 2014). These birds are showing variation in brood patch development in particular, suggesting that some of the local birds are now breeding, while there is still some passage going on (or alternatively a substantial non-breeding population).

A good session in pleasant weather.

Thanks to Heather Coats, Keith Vaughton, Wayne Morris, Darren Hicks, Val Wilson and Phil Mead for company and assistance this morning.

Owain Gabb
23/04/2016

Grasshopper warbler (Keith Vaughton)
Reed bunting (Keith Vaughton)
Sedge warbler (Keith Vaughton)

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