Sunday, 5 June 2016

Oxwich Marsh 4 June 2016 and the year to date

A near windless overcast day on the marsh made for perfect ringing conditions. We put 660 feet of net across the reed bed and in surrounding scrub.

The catch of 80 birds was an improvement on recent weeks. The breakdown was as follows:

Species
New
Re-trap
Total
Great Spotted Woodpecker
2
2
4
Dunnock
1
0
1
Robin
2
0
2
Stonechat
1
0
1
Sedge Warbler
3
2
5
Reed Warbler
2
2
4
Whitethroat
0
1
1
Chiffchaff
3
3
6
Blue Tit
0
1
1
Great Tit
2
5
7
Chaffinch
6
2
8
Greenfinch
2
3
5
Goldfinch
16
11
27
Siskin
3
1
4
Reed Bunting
0
4
4
Total
43
37
80

Fledgling great spotted woodpecker
Fledged young of a number of species were captured for the first time in 2016 including great spotted woodpecker, dunnock, stonechat, chaffinch and goldfinch, while fledgling robins, greenfinches and siskins continued to dribble in in small numbers.

Recaptured birds included a male reed warbler initially ringed in 2013 and now captured in each subsequent year including 2016, a returning male chiffchaff initially ringed in 2015 and a couple of goldfinches and reed buntings ringed in 2014.

Fledgling chaffinch
As we are just over half way through the year, it is now a good time to make some basic comparisons as to how 2016 is shaping up. These are heavily qualified: the amount of net that is erected varies according to available personnel and weather, and the net rides currently in use differ from those used in the equivalent months of 2015 and 2014. Notwithstanding this, some basic observations are possible with regard to various species, and we have had feeders out throughout the period which indicates that it is reasonable to compare finch numbers in particular.

To date 937 birds of 39 species have been processed in 2016 (the table below excludes birds that have been recaptured on more than one occasion - there have been 1263 captures in total). The breakdown is as follows:

Unique birds captured 1 Jan - 4 June inc 2014-2016

Species
2016
2015
2014
Sparrowhawk
2


Water Rail
1


Jack Snipe
5
1

Snipe
6
2

Kingfisher


2
Green Woodpecker

1

Great Spotted Woodpecker
9
7
4
Swallow

1
1
Wren
17
17
14
Dunnock
18
19
18
Robin
14
21
18
Stonechat
1

2
Blackbird
10
9
5
Song Thrush
4
4

Mistle thrush

1

Cetti's Warbler
2
7
5
Grasshopper Warbler
3
2
1
Sedge Warbler
18
8
7
Reed Warbler
16
7
11
Whitethroat
5
3
1
Blackcap
7
16
12
Wood warbler


1
Chiffchaff
16
7
8
Willow Warbler
7
2
11
Goldcrest
10
6
3
Long-tailed Tit
2
11

Coal Tit
4

2
Blue Tit
100
131
127
Great Tit
61
53
43
Treecreeper
1
2

Magpie
1
1
1
Chaffinch
106
106
58
Brambling
1


Greenfinch
58
114
175
Goldfinch
232
185
191
Siskin
142
28
60
Lesser Redpoll
1
1

Bullfinch
2
8
4
Reed Bunting
55
36
83
Total
937
817
868


Most of the warblers that are captured at Oxwich are trapped in the late summer and autumn as birds disperse and feed in preparation for migration. The slightly higher number of sedge and reed warblers to date than during the equivalent period in previous years reflects the fact that we have put more net through the open reed bed in spring and early summer 2016. We have also captured chiffchaff and whitethroat in these nets.  Conversely, Cetti's warbler territories appear to be further from the nets than in previous years, and we have only captured two birds (both retraps from previous years), and blackcaps, while holding territory locally, are thin on the ground.

Fledgling goldfinch
The most notable differences between 2016 to date and previous years have been in terms of finches. We have captured far fewer greenfinches than in 2015 and 2014, while it has been a good year for siskins, and goldfinch numbers are also up on the past two years at this stage. The changes in greenfinch numbers could be the result of disease (trichomoniasis), but we don't have clear evidence for this (we capture occasional diseased birds that are released without ringing). It is also unclear what is driving the apparent increase in siskin numbers (for goldfinch the overall total is not markedly different and a couple of weeks of poor weather would likely see the between year results even out).

The other features of 2016 to date have been some nice late winter catches of jack and common snipe, with a water rail making for a welcome bonus - all were trapped in a rushy area near the South Pond. We have had nothing as unexpected as a spring wood warbler in 2016 (this species was captured in 2014), albeit we were not expecting a brambling on 8 April.

Thanks to all who have assisted at the marsh in 2016 to date, and to Heather Coats, Keith Vaughton and Emma Cole for their company and assistance during the session on 4 June.

Some further photos are below.

Owain Gabb
05/06/2016


Fledgling robin

Fledgling robin

Tail of fledgling robin showing fault bar. This may well prove a useful feature for ageing if this bird is recaptured following completion of its post juvenile moult. The juvenile tail feathers will typically be retained, and their shape, retained greater coverts (in the wing) and the colouration of the inside of the upper mandible are all useful ageing features. 

Juvenile stonechat (Keith Vaughton) 
Drinker moth caterpillar (Keith Vaughton)

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