Wilstone Reservoir CES 2020 summary

The 2020 CES season should have been from the 30th April until the 2nd of September. However, due to imposed Covid restrictions the first visit was actually on the 14th June. 

The birds per session figure was 82.25 calculated by dividing the total of each session's catch by the number of visits,8. This figure compares to 85.75 from 2019 and 67.0 in 2018. 

During 2020 there was a distinct lack of juveniles of resident species. Migrant species juveniles were near or slightly better than in normal years. Blackcap were down after the exceptional influx of numbers during August of last year. Reed Warblers suffered from the reedbed water level being low throughout the summer, affecting nesting and feeding opportunities resulting in a lower than average catch.

In summary, 2020 CES shows it to have been an average year.

Johne Taylor

	Adult	Juvenile	Total
Blackbird	6	1	7
Blackcap	30	87	107
Blue Tit	8	13	21
Cettis Warbler	0	2	2
Chiffchaff	10	70	80
Dunnock	1	0	1
Garden Warbler	2	2	4
Goldcrest	0	1	1
Goldfinch	1	0	1
Great Tit	3	10	13
Long Tailed Tit	0	24	24
Marsh Tit	0	2	2
Reed Bunting	6	0	6
Reed Warbler	77	89	166
Robin	4	20	24
Sedge Warbler	10	70	80
Song Thrush	10	1	11
Treecreeper	0	2	2
Whitethroat	0	2	2
Willow Warbler	1	21	22
Wood Pigeon	1	0	1
Wren	4	23	27
Total	181	401	582

Marsworth, Autumn is upon us.

After a week of wind and rain we grabbed the chance to go out on Wednesday even though it still looked fairly breezy. We put up a few nets in the more sheltered eastern corner of the site and a new net between some hazel trees. I had planned to fill the time with some scrub clearing but it was a busier morning that expected with that interesting mix of the last summer migrants and autumn visitors. We started with Chiffchaffs and Blackcaps and then a flurry of Goldcrests came to the tape lure along with four Bullfinch.

The new net was a success and caught four Lesser Redpoll, a new species for Claire, plus a Chaffinch. The Chaffinch was a young male that had unusually moulted all the secondaries and a couple of primaries on one wing Given the terrible condition of the feathers on the other wing it was likely that he had had to replace similarly damaged feathers. 

Juvenile Chaffinch with new secondaries on right wing compared with tatty feathers on left wing.

All the Redpolls were juveniles, aged according to the shape of the tail feathers and a moult limit along the greater coverts. None were showing any red feathers on the breast so we could not sex them.

Redpoll wing showing 6 old greater coverts

Lesser Redpoll

The last bird of the day was a new Great Spotted Woodpecker which was still moulting its primaries as part of its post juvenile moult. The contrast between the black lesser coverts and the duller greater coverts plus the good condition of the unmoulted outer primary, aged the bird as a juvenile. Its body moult was nearly complete and there were just a few little red feathers left in the crown but the new bright red nape patch means this is a male.

Greater Spotted Woodpecker wing. 

The bright red nape of a male Greater Spotted Woodpecker with just a few red juvenile feather left in the crown.

We finished with 56 birds (11 retraps/45 new)

Bulbous Honey Fungus on dead willow

Marsworth CES Summary 2020

 

Due to Covid restrictions we were not able to start with any CES ringing until mid-June which meant we missed the first 4 sessions.

CES 5 : 15/6/20 (91 birds) Warm and Sunny. Claire and I divided the site between us and used separate equipment. Off to a good start with 91 birds: Blackcaps, Reed Warblers, Sedge Warblers and Cetti’s all with brood patches and plenty of juvenile birds. An unusual Starling roost of about 500+ birds left the reedbed at 4:20am. A male Great Tit was already in main moult. It was a strange start to the season.

CES 6 : 22/6/20 (100 birds) CES 6 was run the same way and was again an excellent catch of 100 birds and included our first Kingfisher since 2016 and lots of juvenile Great Tits.

CES 7 : 7/7/20 (101 birds) A magnificent sunrise with cloud and breeze increasing through the morning. With covid restrictions eased we had 4 ringers and had another good catch of 101 birds. The day was dominated by Reed Warblers and Sedge Warblers. Both species are doing well this year.

CES 8 : 13/07/20 (94 birds) Patchy cloud.  We did not put up net A because there was a Song Thrush nest with 4 eggs half way along the net ride. We caught a second juvenile Kingfisher in the first net round and a third in the last net round, unfortunately Claire N missed both…  Apart from that it was Chiffchaff, Blackcap, Reed Warbler and Sedge Warbler all morning with one or two Robins and Wrens and four Long Tailed Tits in moult. Two Oystercatchers flew over.

CES 9 : 28/7/20 (89 birds) Five Hobbies were hunting over the reed bed when we arrived and a Water Rail was calling at the end of net 1. The breeding season is still in full swing with lots of newly fledged Reed Warblers and six new Cetti juveniles, but a couple of Willow Warblers are a sign that birds are already on the move.

Newly fledged Reed Warbler 2/8/2020

CES 10 : 2/8/20 (79 birds) The Song Thrush was still on three chicks along net ride A and we caught the female in net 2 on the last net round. Two Hobbies flying around. There are strangely very few mosquitoes this year. The Angelika is flowering and some Great Willowherb but the Orange Balsam that usually accompanies it is missing.  Many juveniles now in post-juvenile moult although there are still plenty of very young reed warblers indicating that there has been an extended breeding season. One of the female Reed Warblers L942449 had been ringed in Aug 2012 so is 8 years old. Three juvenile Bullfinch were ringed and the elderberries are starting to ripen.

Heavy rain in August had flattened the reedbed by net 1 & 2

CES 11 : 16/8/20 (54 birds) A misty, murky morning, “greech” we decided was the word. The reed bed had been flattened by the heavy rain over the last week or so, we could see right across to the causeway from net 2. Willow Warblers were moving through and we caught seven. There were also a few Sedge Warblers carrying fat and adult Blue Tit and Dunnock in main moult.

Brown Hawker 2/8/2020

CES 12 : 23/8/20 (43 birds) A breezy sunny start that became cloudier. Two Sandwich Terns flew over as we were putting the nets up. A fairly quiet end to the CES with 43 birds but a bit more variety with Reed Bunting, Bullfinch, 4 more Willow Warblers and a few Long Tailed Tits that were still in main moult.

	Adults			Juv
Species	2019	2019	2020	2019	2019	2020
	CES 1-12	CES 5-12	CES 5-12	CES 1-12	CES 5-12	CES 5-12
Blue Tit	8	3	6	103	86	33
Great Tit	2	1	3	25	24	41
Robin	5	2	7	28	21	17
Blackcap	28	17	22	106	103	51
Chiffchaff	29	16	25	99	85	66
Willow Warbler	5	2	2	10	10	12
Reed Warbler	57	35	56	71	71	101
Sedge Warbler	15	8	26	12	12	28
Bullfinch	3	2	7	0	0	5
Cetti	7	2	6	21	20	17
Reed Bunting	8	0	2	2	2	4

 

Here is a comparison of our commoner birds with last year’s catch. Adult numbers were generally good but there were some big differences in breeding success. It looks like Blue Tits did quite badly whereas Great Tits fared better. We were unable to check the next boxes during lockdown so we won’t know what that was due to. Blackcap and Chiffchaff did poorly compared to last year but Reed Warblers and Sedge Warblers had a cracking year. We obviously had a Bullfinch family on site and Cetti’s had another good year.

Thanks to all the ringers for their help and efforts this summer.

Lynne Lambert