BLAGDON LAKE BIRDS

August 2011 News


Monday 1st August [Warm and muggy]

The juvenile Black-necked Grebe Podiceps nigricollis was off Hellfire Corner feeding around the cormorant trees this afternoon but despite extensive searches by myself (except Butcombe Bay) and Mervyn Pearce neither of us saw any Red-crested Pochards Netta rufina or the Ferruginous Duck Aythya nyroca, so can reasonably assume they have gone. There were 11 Common Sandpipers Actitis hypoleucos, with 6 on the dam and 5 on Home Bay Point.

Alan Bone, Warwick White and I ran both my 125W Robinson moth traps at the Top End from 2200 - 0145 hrs (16 Celsius) and had an amazing haul. We even heard a Barn Owl Tyto alba calling while we were there. Here's the list with thanks to Mike Bailey for the genitalia determinations, and Ray Barnett and Andrew Duff for the beetle identifications:

Tuesday 2nd August [Hot and sunny]

I spent all day identifying last nights amazing moth catch and photographing some of the species that aren't already on the website, so didn't get down to the lake until late this evening. Amazingly, the juvenile Black-necked Grebe Podiceps nigricollis was the first bird I scoped! It was feeding off Rugmoor Point and moved towards Peg's Point later. The lake has dropped another 3% to 70% full (per Bristol Water).

Canary-shouldered Thorn Ennomos alniaria, Top End © Nigel Milbourne, 2011

Wednesday 3rd August [Warm and sunny]

I found 2 juvenile Black-necked Grebes Podiceps nigricollis feeding off Ash Trees this afternoon, with the female Common Goldeneye Bucephala clangula close by. Ironically, I was telling an angler, Brian, how unusual one Black-necked Grebe was and blow me, there were two together! I tried photographing them, but the results aren't worth showing you, unfortunately. There were a few remnants of the Common Sandpiper Actitis hypoleucos fall of a couple of days ago, with one on the dam and two on Home Bay Point still.

I ran my new 15W Heath moth trap with Rich Andrews this evening, for a few hours, at Chew Valley Lake (2200 - 0045 hrs, 18 Celsius). The best find for my trap was a migrant Dark Sword-grass Agrotis ipsilon that Rich spotted as I was taking the trap apart to check the catch. He will publish the list on his CVL Birding website. I had a quick look at the Common Fleabane Pulicaria dysenterica in the Hollow Brook car park for Fleabane Tortoise Beetle Cassida murraea and was able to show Rich both a red adult and a larva. And, talking of beetles, Rich spotted a large click beetle attracted to one of his lights that I was able to identify as Stenagostus rhombeus, which we'd caught at Blagdon on Monday night and had been kindly identified for me by Ray Barnett of Bristol Museum today! In addition, a Common Toad Bufo bufo visited my trap and there were several along the road home including a huge one outside our gate that I moved under the hedge for safety.

Thursday 4th August [Rain early, then sunny spells with a strong westerly breeze]

White horses were racing down the lake as soon as the rain stopped at lunchtime and, try as I might, I couldn't find the 2 Black-necked Grebes Podiceps nigricollis today. However, equally exciting as them, was the summer-plumaged adult Ruddy Turnstone Arenaria interpres on the dam with 2 of the 5 Common Sandpipers Actitis hypoleucos - the other 3 were on Home Bay Point. The female Common Goldeneye Bucephala clangula was asleep among the Tufties off Peg's Point.

One interesting behaviour I observed while on Rainbow Point was 3 of a brood of 6 cygnets of Mute Swan Cygnus olor standing tall on the bank intertwining their necks and calling softly. I initially thought they might be mutual grooming, then thought that they were probably young males practising their 'assertion of status' in the group (play-fighting if you like). I got my video camera out and 'filmed' them for a minute or two before one of the parents broke it up and led them away onto the water. Sadly, when I reviewed the 'footage' which I'd hoped to share with you, my clumsy fingers had switched the video on and off almost immediately and captured nothing of the event! Ho hum.

I found one of the Black-necked Grebes Podiceps nigricollis this evening along the North Shore with a Tufty flock but there was no sign of its pal anywhere nearby. I sat in the Top End hide until dark and watched another of the (too) regular firework displays at Coombe Lodge 1.8 miles away and had a simultaneous view of some roosting dabbling ducks, mainly Mallards Anas platyrhynchos on Wookey Point that were spooked by the sight and sound of the pyrotechnics and flew off. Some Great Cormorants Phalacrocorax carbo were spooked out of their roost by the sounds, but the good old Canada Geese Branta canadensis didn't seem to be bothered by any of it.

I ran a 15W Heath Trap at Top End in a marginal habitat overnight and caught the following:

Friday 5th August [Warm and dry]

It was an early morning at the lake retrieving a 15W Heath Trap run overnight (the list will be published for the 4th, as it is customary to record moths caught in traps run overnight on the date the trap was deployed).

There were good numbers of migrant Willow Warblers Phylloscopus trochilus at Top End some of which were singing in the early morning sunshine. I saw one of the Black-necked Grebes Podiceps nigricollis off Bell's Bush and checked to see if the other was along the North Shore but didn't see it, so it's reasonable to assume there's just the one present now. An adult Common Tern Sterna hirundo was feeding over the dam end and I saw 4 Common Sandpipers Actitis hypoleucos; one on Butcombe Shore and 3 on Home Bay Point.

I ran a 15W Heath Trap at Top End overnight in a meadow and only caught the following (presumably all the harvestmen disturbed the roosting moths which subsequently escaped):

Saturday 6th August [Sunshine and showers]

Another early morning retrieving the 15W Heath Trap which didn't have too much in it other than a good collection of Harvestmen (for results see 5th). I drove through, stopping periodically, to look for any new birds that might be about while I was there and only noted a new brood of mum and 7 juvenile Tufted Ducks Aythya fuligula at Long Bay (1st brood, 2011) and the 3 Common Sandpipers Actitis hypoleucos on Home Bay Point before going home for breakfast.

This afternoon I went back down to try and find the Black-necked Grebe Podiceps nigricollis and spotted it at long distance from Rainbow Point before I was called home to try and catch 'a moose loose aboot the hoose'! The Wood Mouse was duly escorted out of the house and when I went back down later I saw the Black-necked Grebe feeding in the floating weed in Top End and an additional Common Sandpiper at Cheddar Water, bringing the total to 4. I also got a mammal tick, when I saw a young Hedgehog Erinaceus europaeus at Burmah Road. Here's a rather rubbish record shot of it taken with the aid of car headlights before I moved it off the road:

Hedgehog Erinaceus europaeus, Burmah Road © Nigel Milbourne, 2011

Sunday 7th August [Thundery showers]

Mike O'Connor emailed to tell me there was a female Northern Wheatear Oenanthe oenanthe on the dam earlier today. I didn't see it after tea. The Black-necked Grebe Podiceps nigricollis was off Ash Trees with a small group of Tufties and the female Common Goldeneye Bucephala clangula was off Peg's Point with another large group of Tufties. I only saw one Common Sandpiper Actitis hypoleucos on Home Bay Point and none on the dam. There are huge numbers of Aythya ducks present now, mainly drake Tufted Ducks Aythya fuligula and Common Pochards Aythya ferina, so the WeBS count next weekend will be interesting. Together with the large number of Common Coots Fulica atra there will certainly be over 3000 birds present. With the margins starting to show around the Top End we might hope for a passage Spotted Crake Porzana porzana that is visible for a change. We only have two records of two birds at the same time in September 1996. So careful observation may reap some reward in the next few weeks.

Monday 8th August [Gale force westerly wind and cloudy]

There was no sign of the Black-necked Grebe Podiceps nigricollis in the very trying conditions, but I counted 915 Tufted Ducks Aythya fuligula bouncing around in the waves and spotted the adult drake FERRUGINOUS DUCK Aythya nyroca again off Burmah Road / Wood Bay Point. I guess it's been present all along, but just been missed. The other surprise was a juvenile Marsh Harrier Circus aeruginosus that dropped into the marginal vegetation between Peg's Point and where I was standing at Ash Trees not 150 metres away at 1357 hrs. A few minutes later it flew up, drifted over Rugmoor Bay before powering into the teeth of the gale low over the waves towards Rainbow Point. The female Common Goldeneye Bucephala clangula remains off Peg's Point with the Tufty flock there and the 4 Common Sandpipers Actitis hypoleucos were on the dam and Home Bay Point. Other birds of note included a Little Egret Egretta garzetta at Flower Corner a calling Eurasian Siskin Carduelis spinus at Lodge Copse and a flock of 50-60 Common Linnets Carduelis cannabina in a field between Top End and Henmarsh Farm.

In addition, I saw 2 Small Skippers Thymelicus sylvestris and 6 Migrant Hawkers Aeshna mixta for the first time at the lake this year. There were a few each of Emperor Anax imperator, Common Sympetrum striolatum and Ruddy Darters Sympetrum sanguineum also on the wing. All in all a very pleasant 4 hour walk.

When the wind died down a bit this evening I re-found the Black-necked Grebe Podiceps nigricollis off Rugmoor Point at 2000 hrs.

Tuesday 9th August [Dry with sunny spells]

The wind had died down a bit by this lunchtime and I found the Black-necked Grebe Podiceps nigricollis with relative ease off Peg's Point with the Tufty flock and the adult drake FERRUGINOUS DUCK Aythya nyroca was feeding close to Top End hide off Wookey Point. I also saw a Northern Lapwing Vanellus vanellus at Burmah Road, a Little Egret Egretta garzetta at Bell's Bush, a juvenile Ringed or Little Ringed Plover Charadrius sp. on Rugmoor Point, 2 Common Sandpipers Actitis hypoleucos at Ash Trees and the female Tufted Duck Aythya fuligula with her 7 ducklings still in Long Bay. The island (Tiny's Shallow) has appeared in front of the Lodge today and will hopefully act as a migrant feeding and resting place in the weeks to come.

I spent some time sweep-netting for invertebrates at Bell's Bush this afternoon but didn't catch a great deal. Eventually, I was driven off by Twin-lobed Deer Flies Chrysops relictus which were present in good numbers and kept buzzing around my head and arms. They bite!

Twin-lobed Deer Fly Chrysops relictus, Bell's Bush © Nigel Milbourne, 2011

I wanted to check some Small Skippers Thymelicus sylvestris to see if there were any Essex Skippers Thymelicus lineola among them, but didn't find any today. I checked a lot of grass moths and they all appeared to be Agriphila tristella. I also photographed some black appendages on grasses that I wanted to try and identify because I wondered if they were fungi or moth pupae. They appear to be Ergot Claviceps sp. possibly C. purpurea a very interesting fungus that has played a significant part in history e.g. causing ergotism or "St. Anthony's Fire".

Ergot Claviceps sp, Burmah Road © Nigel Milbourne, 2011

I ran a 15W Heath Trap on Home Bay Point last night (12 Celsius) but didn't have a very good return:

Wednesday 10th August [Overcast and cooler than of late]

I was at the lake between 0700 and 0815 hrs this morning and saw the juvenile Black-necked Grebe Podiceps nigricollis off Rugmoor Point again where it was feeding yesterday afternoon. There were 4 Little Egrets Egretta garzetta (3 on Wookey Point and 1 at Bell's Bush), 4 Common Sandpipers Actitis hypoleucos (1 on the dam and 3 on Home Bay Point) and just 7 Canada Geese Branta canadensis (the 350+ post-moult flock has moved off again as usual in August - see WeBS Counts).

I went to Ubley this afternoon and popped down to Top End hide where I spent some time looking for the FERRUGINOUS DUCK Aythya nyroca, but it wasn't until I went down to Bell's Bush that I was able to find it. I think it had been roosting at Hellfire Corner. There had been an influx of Canada Geese from Chew Valley Lake during the day too.

Alan Bone and I ran my two 125W MV Robinson Moth Traps at the North Shore car park from 2200 - 0115 hrs (15 Celsius) this evening. We had a reasonable evening though it tailed off very quickly around midnight. Here's the provisional list:

Thursday 11th August [Overcast with drizzle]

The FERRUGINOUS DUCK Aythya nyroca was reported (on RBA pagers) as still being present this morning and I may have seen it this evening, though I couldn't be sure. I did, however, see the Black-necked Grebe Podiceps nigricollis off Rugmoor again this evening from Rainbow Point where I also watched a Eurasian Curlew Numenius arquata fly west down the lake calling. There was a Common Sandpiper Actitis hypoleucos on the dam and a Green Sandpiper Tringa ochropus along Burmah Road.

The rather startling, Red Underwing Catocala nupta, North Shore © Nigel Milbourne, 2011

Friday 12th August [Warm with drizzle]

I spent a good 5 hours at the lake today and saw the juvenile Black-necked Grebe Podiceps nigricollis off Ash Trees but not the Fudger. A few shorebirds are starting to drop in with at least 5 Common Sandpipers Actitis hypoleucos and possibly as many as 9 present around the lake, a Green Sandpiper Tringa ochropus at Hellfire Corner and an adult Ringed Plover Charadrius hiaticula took a rest on Tiny's Shallow but had gone by the time I got back to the Lodge. A single, very mobile, Little Egret Egretta garzetta stalked around the Top End wiggling its foot in the weedy margins and snaking its neck out to catch small fish and other tasty morsels and an adult Eurasian Sparrowhawk Accipiter nisus washed itself on the shore at Rugmoor Point. I saw or heard 54 bird species while I was at the lake.

Saturday 13th August [Cloudy but warm]

We did the WeBS Count this morning and saw the Black-necked Grebe Podiceps nigricollis off Peg's Point and the adult drake FERRUGINOUS DUCK Aythya nyroca at Top End despite lots of fishing boats moving the birds about on the main body of the lake. We counted 7 Common Sandpipers Actitis hypoleucos and 3 Little Egrets Egretta garzetta of particular interest, together with 1247 Common Coots Fulica atra and 1001 Tufted Ducks Aythya fuligula which provided lots of exercise for the 'clicker' fingers! Eurasian Teal Anas crecca and Northern Shoveler Anas clypeata have started to arrive over the last week or two and their numbers will continue to rise as the water level drops. Now to find the first Garganey Anas querquedula of the year.....

This afternoon while on the internet, I thought about 'Nimrod' the radio-tagged Osprey Pandion haliaetus that dropped in overnight at Blagdon Lake last spring, so went onto Roy Dennis' website to see what he's been up to since then. It transpires he raised one chick last summer and flew back to Africa where he wintered successfully before flying back to Scotland this spring (albeit missing Blagdon this time). As he arrived back late, he was unsuccessful at attracting a mate and raised no young this year. Then, part of his transmitter aerial broke off, so no more data is being received, though Roy says he is still alive and well.

Daniel Hargreaves rang to invite me to join the YACWAG Bat Group in the evening to do some trapping. The plan was to try and catch some Daubenton's Bats Myotis daubentonii from their roost in the grounds of the Pumping Station (but this had been abandoned by the bats) and set up three harp traps and lures along Butcombe Bank (two by the water and one in the woodland). What an extraordinary night we had! We captured 53 bats of 9 species, two of which were new to Blagdon Lake, so far as Daniel is aware:

First are a couple of pictures of the new species. I will add more pictures underneath, including some parasites that Daniel and I collected off the bats, to celebrate a fantastic evening. Thanks to Daniel and the team for the opportunity and teaching me so much. The team plan to check the bat boxes at Blagdon Lake next Saturday 20th August.

Brown Long-eared Plecotus auritus and Whiskered Myotis mystacinus Bats, Butcombe Bank © Nigel Milbourne, 2011

Noctule Nyctalus noctula and Serotine Eptesicus serotinus Bats, Butcombe Bank © Nigel Milbourne, 2011

A flea, possibly Ischnopsyllus sp, A bug probably Cimex pipistrelli, a mite probably Spinturnix myoti and Leptotrombidium sp. mite larvae, Butcombe Bank © Nigel Milbourne, 2011

Glow-worm Lampyris noctiluca, Butcombe Bank © Nigel Milbourne, 2011

We had the added pleasure of seeing a Glow-worm Lampyris noctiluca advertising for a mate, and I took the opportunity to run my 15W Heath Trap in the fishermans car park from 2145 - 0315 hrs (14 Celsius) though there was a poor return for my effort:

Sunday 14th August [Sunny spells with a cool wind in the evening]

While I was at the lake last night I heard a probable Bar-tailed Godwit Limosa lapponica fly over calling at about 0300 hrs but due to getting home very late I didn't bother to go down to the lake again until this evening. There was a really cool wind blowing so I didn't spend ages looking for the two 'rares', I just checked around for new arrivals. I didn't see anything new, just 2 Little Egrets Egretta garzetta and 2 Common Sandpipers Actitis hypoleucos.

Monday 15th August [Sunny spells and late afternoon mizzle]

I only visited late this evening and saw 2 Little Egrets Egretta garzetta and 4 Common Sandpipers Actitis hypoleucos aside from the regular wildfowl fare. I plan to spend some time tomorrow morning having another proper look around for migrants.

Tuesday 16th August [Sunshine and showers]

Well, it wasn't long since my comment on Saturday about finding the first Garganey Anas querquedula, as I found 3 asleep on the bank in front of the Lodge at 1245hrs. A welcome first for the year, as we no longer seem to get them in spring at Blagdon. I had an unsuccessful search for the adult drake FERRUGINOUS DUCK Aythya nyroca and juvenile Black-necked Grebe Podiceps nigricollis and have a hunch that while the 'Fudger' is probably still present, the grebe appears to have moved on. There were 2 Little Egrets Egretta garzetta at Top End and 4 Common Sandpipers Actitis hypoleucos at Bell's Bush, while the female Common Goldeneye Bucephala clangula has reappeared along the North Shore today, after her brief absence for the WeBS Count.

Wednesday 17th August [Overcast with drizzle much of the day]

I went walking today but visited the lake after tea and found the adult drake FERRUGINOUS DUCK Aythya nyroca off Ash Tree and rather surprisingly a Black-necked Grebe Podiceps nigricollis in front of Top End hide as the sun went down. It had a really bright eye and may be a different bird to the one present recently. I'll have a closer look in better light tomorrow morning. There was no sign of the Garganey Anas querquedula in front of the Lodge but they may have relocated to the Top End with the Eurasian Teal Anas crecca but the setting sun made them all into silhouettes so I couldn't sort them out. There were 4 Common Sandpipers Actitis hypoleucos at the dam end and a Little Egret Egretta garzetta at Top End. A young Roe Deer Capreolus capreolus suckling across the lake at the water's edge provided a rather poignant sight.

The lake has dropped another 3% to 64% (per Bristol Water website).

Thursday 18th August [Rain in the morning]

AYTHYA HEAVEN: Having checked Tiny's Shallow (now a spit of land) in front of the Lodge I drove straight to Top End to check the Eurasian Teal Anas crecca and look for last nights Black-necked Grebe Podiceps nigricollis. I was happy, but not entirely surprised given the conditions, to to see 14 Ringed Plovers Charadrius hiaticula (10 adults and 4 juveniles) on Wookey Point, but what happened next was almost beyond belief. I started to check the ducks feeding off the point and one of the first birds I looked at was an eclipse drake Ring-necked Duck Aythya collaris! I rang RBA to put the news out and started to look at it more closely and spotted an Aythya next to it with a peaked crown. Forgetting the 'Ringer' for a moment, it slowly dawned on me that I was looking at an adult female Ferruginous Duck Aythya nyroca. What are the chances of that? I rang Richard Mielcarek, who was at Chew with Keith Vinicombe, and they both came over for a look. We all agreed it was 'a good'un' and with that Richard spotted the adult drake FERRUGINOUS DUCK distantly off Burmah Road as well. Now, to be fair, Richard met me in the Top End hide a couple of days ago and drew my attention to an Aythya duck that was asleep on a branch at Hellfire Corner with its back to us. We both 'grilled' it for quite a while, weighing up the possibility of its being a female 'Fudger', but reluctantly gave up due to the inconclusive views. I wouldn't be at all surprised if this was the same bird (see subsequent comments on 28th August).

Other birds seen during my visit included a Common Sandpiper Actitis hypoleucos also on Wookey Point, a Little Egret Egretta garzetta, and lots of hirundines low over the water including a few Sand Martins Riparia riparia. However, I didn't see the Black-necked Grebe again.

Friday 19th August [Sunny]

I went to the Birdfair at Rutland Water today and only visited the Top End hide at dusk to see if there were any sightings left on the message board. Sadly nothing to report there. However, Andy Davis kindly texted to tell me that he had seen the eclipse drake Ring-necked Duck Aythya collaris and adult drake FERRUGINOUS DUCK Aythya nyroca from the Top End hide today. He also saw at least 12 Ringed Plovers Charadrius hiaticula and 2 Little Egrets Egretta garzetta. I'll have a proper look around tomorrow before we check the bat boxes at 1030 hrs and put out any news if I see anything.

I picked up the latest WeBS Survey Report 'Waterbirds in the UK 2009/10' at the Birdfair from the WeBS team and a quick thumb through showed that Northern Shoveler Anas clypeata and Common Coot Fulica atra occur in sufficient numbers for Blagdon Lake to qualify as a site of national importance in Great Britain.

Saturday 20th August [Overcast with occasional drizzle]

I saw the eclipse drake Ring-necked Duck Aythya collaris off Burmah Road late this afternoon, 14 Ringed Plovers Charadrius hiaticula (10 adults and 4 juveniles) on Wookey Point, though they may have been flushed by a visiting birder on the foreshore (this is not permitted), 2 Little Egrets Egretta garzetta and 4 Common Sandpipers Actitis hypoleucos. There may have been a Black-necked Grebe Podiceps nigricollis in Top End, but it was a bit too far off to positively identify, and I didn't see either the drake FERRUGINOUS DUCK Aythya nyroca or hybrid before I had to leave (but the drake is in heavy moult and unlikely to have gone anywhere).

The bat boxes contained 20 Soprano Pipistrelles Pipistrellus pygmaeus and the last one Daniel and I checked contained an adult male Nathusius' Pipistrelle Pipistrellus nathusii.

Nathusius' Pipistrelle Pipistrellus nathusii showing face and ear detail, Pumping Station © Nigel Milbourne, 2011

Nathusius' Pipistrelle Pipistrellus nathusii penis showing white fringing hair and underwing detail, Pumping Station © Nigel Milbourne, 2011

Three of the bat boxes contained Hornet Vespa crabro nests last year, but we saw none this year. Did the early onset of the cold weather last winter hit them hard? I haven't seen many this year. However, there were at least 45 Copper Underwings agg. Amphipyra pyramidea agg. moths and a few Brown House Moths Hofmannophila pseudospretella in the boxes, particularly those which contained old bird nests. I may do a proper survey of these next autumn when Daniel does the boxes. I don't know why they should be so frequent in the boxes, or, even if this has been remarked upon in the literature (Ray Barnett at Bristol Museum kindly replied to my enquiry and suggested that the Copper Underwings are known to aestivate viz. spend the summer in a state of torpor). Interestingly, three of the boxes in the Scot's Pines Pinus sylvestris ssp. scotica at Indian Country contained huge nests made of pine needles and Badger Meles meles hair which I guess were made by Wood Mice Apodemus sylvaticus - does anyone know if this is likely to be the case? It's a surprise that these particular boxes were used by mammals which would be very exposed to Tawny Owl Strix aluco attack on the bare trunks in reaching the boxes. Please email me if you have an informed view...

Sunday 21st August [Hot and sunny]

I went to the Millfield School nature reserve at Worley Hill with Somerset Invertebrates Group (SIG) today and had a very enjoyable time especially getting the opportunity to photograph Woodland Grasshopper Omocestus rufipes and best of all saw a Hornet Robber Fly Asilus crabroniformis that had caught, and was flying around with, a Woodland Grasshopper before consuming it.

Hornet Robber Fly Asilus crabroniformis, Worley Hill NR, Somerset © Nigel Milbourne, 2011

After tea I got down to the lake and saw that someone had noted seeing a FERRUGINOUS DUCK Aythya nyroca on the Top End hide board. I didn't see either 'Fudger', hybrid or the Ring-necked Duck Aythya collaris but did spot an adult, near summer-plumaged, Black-necked Grebe Podiceps nigricollis off Rugmoor Point - possibly the Chew bird? There were also at least 11 Ringed Plovers Charadrius hiaticula on Wookey Point, a couple of Common Sandpipers Actitis hypoleucos and a Little Egret Egretta garzetta present.

I ran my 15W Heath moth trap at Holt Copse from 2100 - 0615 hrs (10 Celsius) and caught the following:

Monday 22nd August [Warm sunny spells]

This morning the drake FERRUGINOUS DUCK Aythya nyroca and drake Ring-necked Duck Aythya collaris were both still present but mobile due to fishing pressure. I could not find the female 'Fudger' despite looking carefully through the Aythya flocks. The adult Black-necked Grebe Podiceps nigricollis in near summer plumage was also at Top End but being pushed around. In addition I noted 171 Canada Geese Branta canadensis, 2 Barnacle Geese Branta leucopsis, 11 Ringed Plovers Charadrius hiaticula, 2 Common Sandpipers Actitis hypoleucos and a Little Egret Egretta garzetta. A flock of 28 Common Terns Sterna hirundo flew through to the west mid-morning and a new, juvenile, Little Grebe Tachybaptus ruficollis was being fed by one of its parents at Top End (I think there were between 2 and 4 successful broods this year, but it's hard to be precise). I ran a 15W Heath moth trap last night (results 21st Aug) and have added some more information about our bat box checks (see 20th Aug).

Tuesday 23rd August [Cooler and overcast]

The drake FERRUGINOUS DUCK Aythya nyroca was still among the throng of ducks at Top End this morning, but I was unable to spot the Ring-necked Duck Aythya collaris or Black-necked Grebe Podiceps nigricollis. 10 Ringed Plovers Charadrius hiaticula (3 juveniles) remain at Top End, usually on Wookey Point. The burgeoning Canada Goose Branta canadensis flock contained 7 'naturalized' Barnacle Geese Branta leucopsis and there were 4 Common Sandpipers Actitis hypoleucos dotted about still. Welcome new arrivals were 2 Common Greenshanks Tringa nebularia, that settled down to feed along the shore at Indian Country (opposite Top End hide). These are the first of the year.

As I left the lake, I spotted a Great Black-backed Gull Larus marinus sitting in the road over the dam. It clearly wasn't well and it became the largest organism that I've ever caught in my moth sweep net! I put it over the dam wall and it waddled off over the grass and down towards the water looking a bit bemused.

Andrew Duff, Coleopterist extraordinaire, emailed me this morning to confirm that the large beetles that Alan and I caught in the moth traps on the 1st August were indeed the Wasp Diving Beetle Dytiscus circumflexus. He commented "The black and yellow banding on the abdomen, combined with the sharply pointed hind coxal processes, make your specimen 100% Dytiscus circumflexus or 'Wasp Diving Beetle'. This is a Notable B and according to my records is a new 10 km square record." Here are a couple of pictures that I took, before returning it to the lake, where it swam away strongly.

Wasp Diving Beetle Dytiscus circumflexus, Top End © Nigel Milbourne, 2011

Alan Bone, Deve Nevitt, Warwick White and I ran my 2 Robinson traps and the 15W Heath trap at Rugmoor Bay this evening from 2130 - 0015 hrs (14 Celsius) when we were rained off. Up to that point, despite the concerted effort, we had a very poor return, but did pick up 3 new species for the site and we also saw one, or two, Barn Owls Tyto alba:

Wednesday 24th August [Showers]

Mike Jenkins visited the lake before me this morning and reported (per Bristol Wildlife e-group) seeing the drake FERRUGINOUS DUCK Aythya nyroca near Rugmoor Point, the eclipse drake Ring-necked Duck Aythya collaris close in Wood Bay, 2 Common Greenshanks Tringa nebularia and 4 Ringed Plovers Charadrius hiaticula.

Many of the Aythya ducks appear to be drifting away from the lake, presumably to Chew, and I could find none of the 'rares' this lunchtime despite giving it a 'good look'. There is, on the other hand, a steady build-up of dabbling ducks, especially Eurasian Teal Anas crecca. The 14 Ringed Plovers Charadrius hiaticula were still on Wookey Point, and a Little Egret Egretta garzetta was fishing around Top End. I could see a Green Sandpiper Tringa ochropus in Top End as well, when looking from Rainbow Point, but not from the hide because it was feeding on the edge of the bund, hidden from view by marginal vegetation. There are still lots of Aythya ducks along North Shore and I saw the female Common Goldeneye Bucephala clangula, which is putting in an appearance every now and again, in Orchard Bay.

Sunday 28th August

News from Sean Davies who visited the lake today and saw a juvenile Black-necked Grebe Podiceps nigricollis at Top End as well as 2 Common Greenshanks Tringa nebularia, 2 Dunlin Calidris alpina, 2 Common Sandpipers Actitis hypoleucos, a Green Sandpiper Tringa ochropus and a Little Egret Egretta garzetta.

I received a very interesting and thought provoking email from Keith Vinicombe as follows:

"I just thought I'd drop you a line to say that that female 'Fudger' is now at Chew. I saw it from the BK Hide on Friday, but a bit distant and in difficult light. However, I saw it wing stretch and it seemed to show quite a lot of dark on the outer three primaries. Also, it has quite a sharp peak on the rear crown (much sharper than a real Fudger) and the bird didn't look particularly chestnutty. Eventually, it flew and disappeared on its own towards the Dam; in flight, I thought its wingstripe looked quite similar to a Tufted. It's definitely the same as the Blagdon bird as it has the brown spotting on the belly and the dark line up the centre of the undertail coverts. I wasn't really sure what to make of it but I saw it again yesterday from Stratford Hide, much closer and in better light and I came to the conclusion that it's not quite right for a pure Ferruginous - all the doubts I had on Friday were confirmed. Also, at one point it flew with two Tufteds and the three wingstripes were very similar. I think it must be the bird we originally saw on 8th April in Stratford Bay. I watched it then for two hours before coming to the conclusion that it wasn't a pure Fudger. In fact I b******d up my back sitting hunched up looking down my telescope - it took about three months to get back to normal! When I saw it with you at Blagdon, I thought it looked OK but I've had to change my mind I'm afraid, although it certainly looks quite convincing on the face of it."

Richard Mielcarek and I discussed at some length what was presumably the same bird when we first saw it at Blagdon on the 16th August and decided at the time that the views were inconclusive to claim a female 'Fudger'. However, the three of us saw it reasonably well on 18th and although the spotting the on the belly was a topic of conversation, we saw no other features at the time to rule out it being a Ferruginous Duck Aythya nyroca, so far as I remember. Females moult later than males by some 4 - 6 weeks, which are generally in flightless moult between June and August (Kear J. Ed. 2005 Ducks, Geese and Swans, OUP), so it wouldn't be surprising to see some 'odd' plumage features at this time, though 'spotting' is not easy to explain. It is also suggested in the text that partial autumn - winter moult is also undertaken and this may overlap with post-breeding moult. A confusing situation for sure. On the 18th August I saw nothing about the head shape to suggest hybridisation while the bird was diving and feeding, though I did with the bird on the 16th August when it was preening. At that time, the crown was occasionally flattened to resemble a Tufted Duck Aythya fuligula, so it made me sceptical, but not positive, it was a hybrid. Head shape and feather gloss are very variable features, and whilst I use shape as a key feature to try and pick out vagrants in Aythya flocks, I know it is unreliable on its own. This was something I noticed very early on while watching the various drake Lesser Scaups Aythya affinis that have turned up at the lake. Not only did they frequently flatten their head feathers when feeding, but the gloss colour would change significantly as well, either due to angle relative to the sun or due to a film of water on the feathers of the head. This resulted in an appearance contra to identification criteria given in many authoritative texts, albeit briefly. Unfortunately, at no point during my observations did I see the "sharp peak on the rear crown" alluded to by Keith in his email, but again, this could be a recent temporary moult feature. I am happy to accept that there is now a question over the identity of the female bird we saw at Blagdon on the 18th August, Keith and Richard have far more experience of female Ferruginous Ducks than me, but I will try to spend some time at Chew and WWT Slimbridge photographing and comparing the birds to provide more information that will contribute to a better understanding of the moult features we might expect to see at this time of year in female Ferruginous Ducks and Aythya hybrids that resemble them.

Tuesday 30th August

The lake is now 59% full (per Bristol Water website) compared with a level of 47% on 24th August 2010.

Wednesday 31st August

More news from Sean Davies today, who saw the juvenile Black-necked Grebe Podiceps nigricollis, 2 Common Greenshanks Tringa nebularia and 3 Common Sandpipers Actitis hypoleucos at Top End, as well as 2 Ringed Plovers Charadrius hiaticula and 2 Northern Wheatears Oenanthe oenanthe at the Lodge.