Marsworth CES 4 - What's Missing?

All CES nets 560'
Sunny, warm, calm.
Ringers LL, GK, CK, AK
4:45am - 11am

Species	Adults	Juveniles	Total
Blackbird	2	1	3
Blackcap	5		5
Bullfinch	1		1
Blue Tit	1		1
Chaffinch	2		2
Chiffchaff	1	1	2
Great Tit		3	3
Reed Bunting	1		1
Reed Warbler	5		5
Robin		3	3
Song Thrush	3		3
Sedge Warbler	1 not ringed
	21	8	29

A beautiful morning even though the rain during the week has given us waist-high nettles and some serious mosquitoes. The new insect repellent I had bought in anticipation of my imminent Scottish trip was sadly ineffective. The Cuckoo was back and stayed with us most of the morning and the reed bed was alive with Reed Warbler song. Common Terns were flying low over the reservoir in the early morning light. The catching was still slow even with the first juvenile Robins, Great Tits and Chiffchaff. Another four new Reed Warblers has brought our numbers up to around normal but where are our Sedge Warblers? The only one we caught today had a good brood patch but had knemidokoptes mite infestation on both legs and was not ringed.

We checked our nest boxes and ringed a brood of 5 and another brood of 8 Great Tits. One Stock Dove nest has been predated but the other box held two large Stock Dove chicks plus two warm eggs. The female must be incubating another clutch while still feeding her chicks.

Wavy Bittercress

To make up for the lack of birds in the nets we had a nice selection of insects!! including a massive Hornet that we managed to release rather nervously, various beetles and a Bumble Bee. There was an interesting plant growing in our net ride but after a second visit with a plant ID book turned out to be Wavy Bittercress, nice but not rare.

When I got home I did some work comparing our results with the last 5 years to try and identify why our catches are so low.
The table below shows the species we catch most and it is clear that while there is a general reduction across the board there is a serious drop in Sedge Warbler and Chiffchaffs. Dunnocks, Reed Buntings and Wrens are also down and we are totally missing many of the birds that we normally catch in small numbers such as Goldcrest, Lesser Whitethroat, Whitethroat and Treecreeper. We have also not caught Willow Warbler or Cetti's Warbler although we have heard them singing each time.
Last year started with low numbers and picked up from session 5 onwards so I hope that pattern will repeat.

Species	5 year average for sessions 1 to 4	2018
Total for all species	124	97
Blackbird	9	9
Blackcap	15	14
Blue Tit	5	5
Bullfinch	3	1
Cetti’s Warbler	6	0
Chaffinch	2	3
Chiffchaff	19	6
Dunnock	8	1
Great Tit	4	6
Long Tail Tit	10	5
Reed Bunting	9	4
Reed Warbler	29	24
Robin	8	5
Sedge Warbler	17	2
Song Thrush	6	5
Wren	8	5

Speckled Wood on False Brome (Brachypodium sylvaticum)