The Wurzels once sang about a giant marrow, to the immortal words “Oh what a beauty / I never saw one as big as that before”. I can’t imagine what they were referring to. Anyway, today in beautiful winter sunshine after days of rain, it was perfect weather for digging brambles out of the South-facing butterfly bank above the old railway track (which I’m standing on in the photo). The ground, too, was ideally soft and well-watered, so the roots came out with hardly any digging. Just before it was time to stop, my fork struck a large lump of wood, right under a small tuft of bramble stalks. I removed the loose earth above it, and made out to my pleasure half-a-dozen stalks that had been clipped off at ground level in earlier years as too difficult to dig out. Well, today was the day, and after really not very much wriggling with the fork, pulling and leaning on the fork handle, I triumphantly wrenched this grandfather-of-all-brambles from the ground, including to my surprise the yard-long taproot below my right hand. In short, a monster, if not a marrow.
The bank, by the way, is the reserve’s best place for Gatekeeper butterflies – we saw 35 there at once, on a stretch of the bank which was well weeded and grassy at the time. Now we have a far longer stretch all de-brambled at once, so perhaps we’ll have a bumper butterfly year, let’s hope so. And there are quite a few young Buddleias (“butterfly bushes”) self-seeded on the bank, a pleasantly “railway” feature, so the signs are good.
The day was exceptionally warm after the chilly winter weather. The hedgerow plants dripped gently. I liked the colours and light on these blackened rose-hips, still somehow looking invitingly fruity.
The path too was covered in blackened leaves, wet and slippery. On the lake, half-a-dozen Goldeneye, a couple of Pochard, a few Teal, some Tufted Duck, a few Mallard. Apart from the ducks, a couple of Cormorants, two young and very white Great Crested Grebes. On the meadows, a Green Woodpecker, flocks of Goldfinches, scattered Redwing and Fieldfare, a flock of Carrion Crows.
Well, after all those sunny late autumn days – it seemed to go on all through October and November, and even in Mid-December it was still as much as 15 C, extraordinarily warm – it is time to get back to talking about conservation work.
Volunteers, a corporate group, and trainees took turns to coppice and dig out the mud in the “Mangrove Swamp” (Willow carr). The newly-qualified chainsaw specialists managed to lay two willows, carefully avoiding felling them completely, to add to the artful tangle of almost-mangrove trunks over the newly-deepened water, thus giving a surprisingly “natural” look after a great deal of work.
Birch Nursery Deadhedge completed
We then dragged the cut willow to the edge of the new Birch nursery area. Several Birches have already fallen (you can see a large trunk in the photo), and many others are on their last legs, covered in ivy and only waiting for a winter storm to bring them down. So we have cleared a sizeable patch of bramble to allow seedlings to grow, and protected the area with a woven deadhedge: two lines of sharpened willow stakes (front and back of the hedge), woven with snibbed willow wands, and packed with willow twigs in between. We’ve planted a few saplings we found around the site – an oak, a birch, two hazel – and we hope they’ll be joined by many small birches in due course.
Corporate group from Mace enthusiastically digging out the ‘Mangrove Swamp’. The succession leads from open water to willow carr (wet woodland) to forest, and since we’d like a variety of habitats, we need to work to turn back the clock a bit!
Ivy Bee, Colletes hederae: female on the spoil she’s dug from her burrow (top) on the steep bank trodden bare by the reserve’s young foxes
It’s not every day a new species turns up, but here’s one. The Ivy Bee, Colletes hederae, was only described in 1993. It’s a European plasterer bee that likes warm dry sandy soil, and provisions its nest with Ivy pollen (Hedera, if you didn’t get it). The eggs hatch into larvae, which eat the pollen and overwinter in the burrow. The adults emerge the following September; the females dig burrows and energetically collect the pollen which is only available then, while the males laze about, fight, grab females and mate, boast about the women they’ve laid, and drive fast cars. Well, I lied about the last two items, obviously. In 2001 the species arrived in Dorset, and it has since spread across southern England, for instance finding good sandy sites in Oxfordshire. Now in 2016 it has come to Chiswick.
We’re happy to report that the bare sandy ground on the steep south-facing bank has turned out to be ideal for this rather special bee. The young foxes seem to lark about and run up and down the bank every morning, which keeps the vegetation very low with plenty of bare soil. This is just what mason and plasterer bees like, and the ground is full of nest holes.
My thanks to Mick Massie for bringing this species to my attention.
Hammer upHammer down
While we weren’t being diverted to photograph the Ivy Bee, we spent the day sorting out the low fence along the ramp path. Here’s Netty and the team whacking a post. I did quite a lot of digging and a fair bit of sawing.
Digging a post holeToo narrow and deep to use a spade
The screech and clatter of the Piccadilly line train filled my ears as we rattled, mercifully quickly, deep below the city centre in London’s fastest and loudest tube line, on the way to Manor House.
I emerged into the grey urban jungle of the Seven Sisters Road, the cars whizzing past the fast food shops as if to escape as soon as they might. Hooded youths hung about the estate gardens in small disconsolate groups. Women scuttled past, heads down, on the grimy pavements. I consulted my map, strode eastwards as purposefully as I could, and crossed into Woodberry Grove.
Woodberry Down
The gleaming new towers of “Woodberry Down” rose on either hand, the street lined with clean young trees and gleaming black cars. Even the pavements were newly laid in handsome yellow-brown flagstone. It was evidently a shinier, more prosperous Manor that the developers had had in mind.
Woodberry Wetlands gateway
Around the corner lay the entrance to London Wildlife Trust’s newest reserve, Woodberry Wetlands. It too was carefully landscaped, and money (from Berkeley, Thames Water and the National Lottery) had evidently been lavished on the gateway itself, a cunningly strong rust-coloured hut of iron, the reserve’s name laser-cut right through the metal walls on both sides. The building straddled the New River, a natural moat; and the gatehouse had its own portcullis, in the form of robust iron gates, locked at night.
London Bat Group arriving for a night’s trapping. The New River is in the background
Huma (of Vole Patrol fame) and two other members of the London Bat Group arrived by car, carrying two enormous Harp traps in big red ski bags. I helped them over the footpath gates, locked to keep people away from bird nesting areas in the breeding season, and they walked around the reserve to a good place under the trees to set up their traps. They are doing some trapping as part of the National Nathusius Project, to learn about that species’ ecology and distribution in Britain.
Woodberry Wetlands (East Reservoir)
I walked along the broad new boardwalk to admire the reserve, a ring of reedbed and bushes around Thames Water’s East Reservoir. A Mute Swan dabbled peacefully; a few Mallard and Coot prepared for nightfall. I counted 66 Swifts whirling about the three grey towers across the water.
Woodberry Wetlands cafe
In an old Water Board building, elegantly converted to a cafe/meeting room, were waiting soft drinks and an excited crowd of the lucky few who’d managed to get tickets for the bat walk.
Huma ran in, a little late, but evidently excited by the result of putting up the traps. She quickly told us a little of the myth and truth about bats – they never get in your hair, they don’t really drink blood (well, vampires do exist, but they’re tiny, and they lap up a few drops of the blood of peccaries (wild pigs), unless humans cut down their forests, remove the peccaries, and then insist on lying with feet poking out of mosquito nets).
She introduced our local bats, too, painting colourful portraits of their respective characters.
The largest, the Noctule, is “military”, flying high, fast and straight, echolocating loudly on each downbeat of its broad wings, with sounds heard in a bat detector set to around 20 kiloHertz as “chip shop chip shop”, slow and regular. The Serotine is “funky” by contrast, with shaggy fur and uneven calls; the middling Leisler’s, a relative of the Noctule, is halfway between the two.
The small bats, the Pipistrelles, call at frequencies depending on their species: the Common “Pip” at 45 kHz, the Soprano Pip at 55 kHz, and Nathusius’ Pip (a migrant from Europe that Huma hopes may be here) at 39 kHz. All of them have a distinctive, low, jinking flight as they pursue their agile prey; and all, too, accelerate their echolocating calls into a feeding buzz or trill as they close in on their prey, getting more and more accurate positional information exactly when it is most needed.
Learning how to use a bat detector
We picked up bat boxes, little miracles of electronics with a sensitive ultrasound microphone, speaker, and illuminated setting dial. They work by heterodyning the signal: that is, you guess or choose what frequency you want to listen out at, say 20 kHz (too high for nearly everybody’s hearing), and the device subtracts that from the signal received from the bat, if one is calling. The difference, if you have guessed close to reality, is a low frequency, say 1 kHz, which you can hear. If the bat is calling in bursts (which radar engineers call chirps), you hear those as patterns of clicks.
Listening out for bats
We went outside and fiddled with the controls. Clouds of gnats, and some nibbling to our ears and cheeks, as well as the whizzing Swifts, proved there was abundant insect food on the wing for any bats that might deign to turn up. Nothing.
Suddenly the air was filled unmistakably with the loud, distant, slow handclaps of a Noctule bat. The Germans fittingly call it the Grosse Abend-segler, the Great Evening-Sailor, as it strides boldly across the dusk sky. We saw no bat, however, just a few Swifts. Presumably the Noctule was far away, its calls detected by our sensitive electronics. We scanned the sky in hope.
And then there was one, plain to the naked eye. And another, and another, and yet more. Five Noctules at least whirled above our heads, uttering loud claps in chorus. With binoculars they looked exactly as you’d think, large batwinged shapes black against the still-glowing sky. Since I was on duty as a helper, I passed the binoculars around; and everyone who looked managed to see what we had come for, bats wheeling joyfully, plentifully, close by, in a London summer sky.
Huma leading the bat walk
Huma led us on. Between the New River and the reedbed, with bushes and small trees all around, Pipistrelles darted and swerved, buzzed and clicked. They were harder to get in binoculars than their larger cousins, but it was possible. Heterodyned clicks and claps played a chorus all around. Excited fingers stabbed the sky. A Little Egret flapped slowly overhead, on its way to its night roost. The urban jungle felt very far away.
We were called forward in little groups to a gate to see the trapping. Huma came up and showed us a Daubenton’s Bat, her hands gloved against small sharp claws and insectivores’ teeth. The species is a specialist in hunting low over still water: it can scoop up insects from the water surface with a cunningly-designed flap, and if it should fall in, it can swim and take off again safely. The London Bat Group was carefully weighing and measuring the little mammals, and then releasing them. They were using a lure designed to attract Nathusius’ Pipistrelle: it also attracts Daubenton’s, hence the catches. But they did catch a female Nathusius’: Huma was delighted.
London Bat Group with their Harp traps. Bats strike the fine mesh and fall into the soft containers below. The bright reflections are of flying insects.
Let’s end with a closeup of the main photo. It’s not every day you see a Daubenton’s Bat face to face, let alone in a capital city.
Huma and John on Vole Patrol with Mammal Nest Box in Perivale Wood
We revisited the nest tubes and nest boxes that we put up for small mammals in four of the Vole Patrol study woods a few months ago. It seems another world: bare leafless trees over chilly wet forest floor have been replaced by a thick green mantle over a mass of brambles that seem to have shot up faster than tropical bamboos and bananas (my father maintained that he could watch a banana leaf unfurling while he shaved in the hospital he was running in postwar Malaya, but I digress).
So it was a case of first case your hare, or rather, first find your small mammal box. Gunnersbury Triangle’s densest parts are pretty thick, and the nest tubes had been put up somewhat at random as the new team did its enthusiastic best on its first day of training all those months ago, followed by the brambles doing their enthusiastic best to hide all traces. We did well to locate 14 of 18 nest tubes: none of them seemed to have been used. We moved on to Perivale Wood, where stout wooden boxes like bird nestboxes had been tied to trees in a much more regular array, and we found them without too much difficulty.
Mammal nest box used by Wood Mice, with opened hazelnuts
Three of the Perivale boxes were inhabited by Blue Tits, the helpless youngsters lying inside while (we suddenly realized) the alarmed but brave parents chattered excitedly outside. We closed the lids and backed off as quickly as we could. The boxes have the openings on the back to encourage mammals and discourage birds, but it’s of only limited value against sharp-sighted Blue Tits. One of the boxes had certainly been used by mammals: two hazelnuts had been opened by small teeth, their ends neatly gnawed to circular holes. I’m not certain I understand how a nut can be withdrawn through such a little hole.
Off to Tentelow wood through the grinding traffic. A game of cricket was going on in the playing fields; it was hot in the sun, a lot cooler under the canopy. The nettles were waist high, the brambles thick. It seemed impossible we would find any of the nest tubes, but we did, eventually. A Scorpion Fly perched on a bramble leaf beside the path.
Sir Thomas Gresham’s symbol, a golden grasshopper (a pun on his name, Grass-Ham), at his building in Lombard Street (photo: Wikimedia Commons)
Then we drove down to Long Wood, part of Sir Thomas Gresham‘s Osterley Park estate. He liked insects enough to use a golden grasshopper as his symbol, punning on his name, which might be Grass-Ham, village in the grass. It’s a beautiful wood, coppice with fine tall straight Oak standards, a proper stream running clean through a steep-sided valley, sullied only by the continuous roar of the M4 invisible above. Chiffchaffs and Blackcaps sang above the din.
Brown Silver-line Moth Petrophora chlorosata at Long Wood, Osterley
I disturbed a Brown Silver-line Moth, which flitted among the nettles and bracken. We saw Holly Blue, Speckled Wood, Large White, and Red Admiral butterflies: it looks a fine place for Purple Hairstreak too.
Acorn Weevil, Curculio glandium
When I got home, I found this funky weevil under my shirt. It looks very much like the Acorn Weevil, presumably from one of the many Oaks I walked under.
Well, at last it’s warm. The anticyclone is heating up the air nicely, a couple of degrees warmer each day. The air is buzzing with hoverflies, and luckily with Mike about, we can actually put names to them. This one, a really remarkable bumblebee mimic, is Criorhina ranunculi – nothing to do with buttercups (Ranunculus), but a species whose larvae live in rotting wood, and it does have an odd nose (rhino-). Quite an unusual species.
Myothropa florea, a wasp mimic hoverfly
This one, Myothropa florea, is a much more typical hoverfly, mimicking a wasp. Mike says he’s recorded some 18 species in the Gunnersbury Triangle LNR.
Nomada cf flava male cuckoo bee
This is a male Nomada cuckoo bee, a brood parasite of other bee species. Its jizz is quite wasp-like in flight, with a flash of aposematic yellow-striped abdomen looking distinctly worth avoiding. At rest, it looks much more like the bee that it is.
Andrena (broad-headed) bee
Andrena cf nigroaena on new Hawthorn leaf
This honey-bee-like insect, in contrast, is obviously a bee, and not a parasite. If you’re used to honey-bees, you’ll notice it has a markedly short head, shorter than it is broad: all the Andrena genus are like this. The head can be short because the tongue is also short, the genus being adapted to short-tubed flowers, so evolution has economically saved energy on building a wastefully long head.
Tiny tadpoles in the shallows
Down at the pond, the sun sparkled on the clear water; a newt or two lurked between the weeds; and dozens of tiny tadpoles wriggled in the shallows. The Mallard pair swam about just below us, greedily feeding. I hope they miss some of the tadpoles.
Women volunteers at work
We hammered in a line of posts for the log hedge, to reduce the number of sticks finding their way into the pond. The ground was rather stony in places, and the iron bar came in handy to break through the stony layer first.
As we did the butterfly transect (Green-Veined White, Brimstone, Holly Blue, Speckled Wood, Large White), we saw a Sparrowhawk swoop into a tree, whistling to his mate. So it seems they’re nesting here again this year.
Jo planting out cornflowers, poppies, climbing nasturtiums and foxgloves
Back at the ranch, Jo was planting out some nice-looking small cornflowers, poppies, climbing nasturtiums and foxgloves raised by the Chiswick Horticultural & Allotments Society’s greenhouse team.
Two days later, the Swifts arrived in the skies over Chiswick, bringing their screaming flight calls to announce summer.
Well, it isn’t every day one visits 3 nature reserves, but today I had a look at Hillingdon NHS’s Harefield Place LNR, London Wildlife Trust’s Frays Farm Meadows SSSI, and Denham Lock Wood to boot.
These are by London standards remarkably secluded and inaccessible, which is to say you need to know where to park and which way to walk, as there’s basically no indication on the ground until you arrive, and even the LWT website is misleading.
Whatever the reason, it’s a delight on a fine spring day to find woods alive with Chiffchaffs and Blackcaps, a pair of Greater Spotted Woodpeckers calling and chittering with excitement directly overhead (and visible in the still nearly-leafless trees), the Blackthorn in delicate white clouds of new blossom, and a Roe Deer skipping away across the meadow, stotting slightly and flashing its “I’ve seen you, I’m running away, and I’m faster than you so don’t bother” white rump-patch. It’s what zoologists call an honest signal, something that benefits both predator and prey. The predator is saved a wasted chase, and the prey gets away without hassle to live another day.
Canada Geese overhead
I walked in on the Golf Course path, a pleasant trek down the hill, past the lakes and along the muddy track through the willow woods. There are only our resident wildfowl at this time of year – Canada Geese, Egyptian Geese, Coot, Moorhen, Mallard, Tufted Duck, Mute Swan, Great Crested Grebe: presumably all breeding right here.
The track was studded with deer slots, and it was nice to have my “Roe Deer” slot identification confirmed with a broad-daylight sighting. Out of the woods, it grew hot, and I discarded coat and pullover.
An early Peacock butterfly
A few butterflies flitted about – Brimstone near the brambles, a Meadow Brown or two, several Peacock.
and a Vole Patrol poster
I met another LWT volunteer, Daniel, who it turned out was not only checking the local boardwalks, but had got up at 5:30 am to do the Vole Patrol on his local patch here! I said I volunteered at Gunnersbury Triangle, and he said he knew who I was, he read my blog (Hi Daniel!). We talked of Kingfishers and conservation and being bitten by small mammals. He asked me which group I particularly liked, birds, butterflies? I said dragonflies, but it was a bit early for them. Sure enough, a minute later, a damselfly flew past! I got my binoculars on to it but had no chance to identify it to species (Large Red is our earliest, but I saw no colour). Still, a distinct surprise so early in the year. Perhaps they are hatching earlier with the warmer climate.
On the way out, I passed a Vole Patrol poster. Huma, the small mammal expert in charge of the project, really can’t be getting a lot of sleep travelling all over West London like this and trapping every day.
I walked across to Denham Lock, an attractively rustic spot with a line of narrowboats, traditional wooden lock gates and a delightful lock-keeper’s cottage complete with teashop.
Denham Lock
A pair of Grey Wagtails flew about as if they owned the place, landing in the trees beside the canal, a few steps from where I took the photo. They must be breeding here too.
The English seem unemotional … except for their passion for nature
