2021 CES 1 Marsworth A good start.

 02/05/2021

Calm, cool and patchy cloud, some brief showers later.

LL, CN, CK, LAM, GK, NM

One of the CES nets (net 3)

With plenty of hands the CES nets went up quite smoothly and LAM,CK and GK went on to put some extra nets up further along the back of the reservoir where there is more dry scrub. It was cold but not as cold as it has been lately, and conditions were good. A Whitethroat was singing near net 4 which is unusual. Our first CES bird was a Sedge Warbler and it looks like over-winter survival may have been good for this species that spends the winter in Africa south of the Sahara as far down as South Africa and Namibia. There was a big influx of birds last week when the wind that had been blowing fairly constantly from the north for the last few weeks eased. We caught 5 today in the CES nets including a retrap male from 2019 and a female from 2020. 

Chiffchaff and Blackcaps are also present in good numbers already with retraps from 2019 and 2020 including a control Blackcap, we will need to wait a few days before we hear where that bird was ringed.  Blackcaps, Chiffchaffs, Wren, Blue Tits, Great Spotted Woodpecker and a Song Thrush were already on nests. It was interesting that the male woodpecker had a full brood patch indicating that the males must share the task of incubating the eggs. We caught a Whitethroat mid morning that burst into song as soon as it was released.

Male and female Common Whitethroat (photo C.Nuttall)

The extra nets were definitely worth the effort as the first bird brought back was a Grasshopper Warbler. This bird breeds in small numbers in Herts and needs undisturbed rank grass/herbage to build a nest. Another two Sedge Warblers were also caught in the extra nets and four Reed Warblers. One was a bird ringed in 2017 and not retrapped since so perhaps he has been spending his summers for the last four years close by, but just out of reach of the CES nets.

Grasshopper Warbler (photo L.Marriner)

The first Cuckoo arrived at 10:15am ahead of some thick rain clouds, he was very mobile flying between Marsworth and Wilstone Reservoirs, briefly perching right above our heads.

The biggest surprise of the morning was a male House Sparrow in net 2 - a new species for Marsworth and for Luke. There are often Sparrows around the reservoirs especially when there is a big hatching of flying insects and the sparrows are feeding young but I have never even seen one this far away from the buildings where they nest.

Male House Sparrow

	CES New birds	CES retraps	Extra nets new	Extra nets retraps
Reed Warbler	3		4
Sedge Warbler	2	3	2
Grasshopper Warbler			1
Chiffchaff	2	4	1
Blackcap	1	4
Robin		2	1
Blackbird			2
Song Thrush		2	2
Wren	1	2
Dunnock				2
Blue Tit		2
Great Tit				1
Goldcrest		1
Whitethroat	1		2
Willow Warbler	1
Great Spotted Woodpecker		1
House Sparrow	1
Reed Bunting		1
	12	22	15	3

 The average for the last 10 years is 34.6 for CES 1 and we caught 34 today. However one of the nets has been affected by the work done by HMWT over the winter to improve the reedbed. Excavator work to lower the reedbed and keep it wetter means that the end of net 7 is completely exposed and will not catch the usual numbers of reed and sedge warblers until the reeds grow back up. Thanks to some fantastic work by local volunteers we have a boardwalk ready for when this happens.

Lynne Lambert