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!
Today I set out between the showers to survey the Swifts, if any, near Chiswick Mall. Equipped with a map and instructions, I chose six viewpoints at road junctions, and cycled between them, keeping a sharp eye out. By St Nicholas’ Church, three House Martins wheeled overhead, but no Swifts.
Up the Mall, near Chiswick Lane South, one Swift hawked high over the river, as did a pair of House Martins, quite an encouraging sight:. There were six nests in good condition on Field House, and within a minute I saw two Martins fly in and out of a nest.
Down the beach in front of Chiswick Eyot, a Little Egret trotted up and down in the water, showing off its elegant figure and yellow feet, and stabbing rapidly at invisibly tiny fish.
Nil to report at Eyot Gardens, despite the handsome tall terrace of red brick houses that once held many House Martin nests. No malice had been shown the colony: probably the loss is due to the dangers of the Sahel (and the guns of the Mediterranean).
Round the corner in British Grove, I was surprised and delighted to see two Swifts overhead – quite high, twice the height of the buildings, so no indication of a nearby nest, but still nice to see them.
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 ‘March Winds’ part of the old proverb came startlingly true on the night of the 27th of March, when two fine big Birch trees blew down, leaving a sad gap. We will perhaps build a wicker dead-hedge and plant a live Hawthorn hedge (to be laid) at the edge of the area, and might even plant some saplings, we’ll see.
Meanwhile, there were branches to be cleared – this one snapped from a Willow just coming into leaf and catkins – and I popped it onto the pile blocking an unwanted path at the end of the picnic meadow. Laura was so surprised to see me “carrying a tree” that I had to pose for the photo.
Seven-Spot Ladybird
Spring is however arriving, the first Blackcap on the reserve starting to sing on 3 April.
Among the newly-visible insects are Brimstone and Comma butterflies, Seven-Spot Ladybirds, plenty of bumblebees and early hoverflies (that’s a species), and a few Bee-flies (bee mimics) hovering as they drink nectar.
The male Sparrowhawk, too, flew over as we worked.
Yes, luck was with the Vole Patrol today. We caught two species of Vole as well as the inevitable Woodmice.
The Field Vole is, as you can see, grey-brown above, and is softly countershaded a la Abbott Thayer (who thought all animals were camouflaged in this way, even flamingoes, but I digress) from top to bottom with no sudden dividing line between dark and light. It’s diurnal and (therefore) has small eyes. And it has a notably short tail, 30% of its head/body length.
Huma very happy after Field Vole
Huma, despite days with almost no sleep, looked and sounded delighted we’d caught this species.
We had turned up in the still-sleeping suburb of Hillingdon before 6am. The journey in was strangely easy on the empty roads, a fox running across in front of me in Acton with a jaunty air.
Vole Patrol arriving Gutteridge Wood 6am
It was at once obvious on arriving that Gutteridge Wood, made a nature reserve by the Greater London Council in its closing days, was something different — an ancient woodland with fine Oaks as “standards” in between coppice stools of Hazel (cut on a regular cycle, so many shoots come up as useful poles from each stump), with Yew and Holly here and there, and English Bluebells and Woodrush as ground cover.
Gutteridge Wood Bank Vole
The team found a Bank Vole in one of the Meadow traps. It is a nocturnal mammal, unlike the Field Vole, and accordingly has big eyes (for seeing in the dark). It has a longer tail, 50% of its head/body length (try measuring it!), is appreciably redder than the Field Vole, and is more sharply white below.
While people were out picking up traps in the wood, a Woodcock flew right overhead, just above the bare treetops. Its enormously long beak and plump gamebird body were unmistakable, which was just as well because I haven’t seen one flying for many years now: a fine sight. Greater Spotted Woodpeckers drummed loudly; a Green Woodpecker gave its cheerful loud call. I guess you could easily guess what habitat I was in just from the names of those three species!
Huma picking up a trap by the pond
The meadow and pond area was once a sewage works; if you peer closely at the pond in the photograph here, you’ll see behind the Reed Mace a circular brick structure left over from those days. It looks very much part of the waterscape today.
The Vole Patrol puts traps beside water, as here, along meadow edges (as above, for the voles), in a grid in the woods, and a few feet off the ground in the trees, to sample the small mammals in the different habitats on each reserve. Unsurprisingly, but very pleasingly, the ancient woodland of Gutteridge has given us good numbers of Woodmice, Shrews and Voles. It will be a pleasure to come back and listen to the Warblers in April or May, and to enjoy the Bluebell woods in the sunshine.
Well, after 7 Vole Patrol postings, and some very cold, wet and early mornings, I felt like enjoying a nature walk in the sunshine, away from Woodmice. But as I left town I found myself in fog, not too thick to be sure, but fog nonetheless.
I was rewarded, however, with the lovely sight of the willows along the lake seeming to float, isolated in the smooth sea of soft gray.
As the mist slowly lifted, a pair of Goosanders and a pair of Goldeneye (the male displaying, the female in tow a yard behind) could be seen through the mirk.
I couldn’t get away from the mammals, either. I was pleased to see not just the usual Muntjac prints along the path, but Roe Deer too. A little way further, and there was a Wood Mouse hopping in a relaxed way across the path, before diving down its hole.
It went thattaway: Wood Mouse hole
Among the birds calling were Green Woodpecker (finely), Great Tit, Song Thrush, Cetti’s Warbler. A Heron and a Parakeet flew overhead. Wood Pigeons and Carrion Crows watched warily.
The damp air had another good effect: the lichens looked wonderful, and even the bristly Ramalina were soft.
Parmelia caperataRamalina colony, generally hard, and the same both sidesEvernia prunastri colony, always soft, and different below
It was nice to see the lichens flourishing so close to London (and Heathrow): these little fungus/alga plants are very sensitive to pollution, and when I was a boy they were almost impossible to find anywhere near a city, so conservation stories can be happy.
My wife looked at me with a mixture of surprise and concern as I made for the door without breakfast. At least have a coffee, she said. I poured a cup of the hot steaming milk and espresso, and drank it alla Milanese, standing up, rapidly, with a minuscule bite to eat, before rushing off to work. Though in my case it was not so much with immaculate suit and the slenderest of briefcases, as with gumboots and mountain waterproofs from top to toe.
The traps had been out overnight, not so cold now but definitely wet. I went off to pick up a row of traps: all six had been triggered, and they felt heavy, as if mammals were within.
Back at the analysis point, Huma and Ollie had set up a Base Camp that Bear Grylls would have been proud of — a neat tarpaulin arrayed with all the equipment, underneath a canopy stretched on baletwine between four trees. The rain dripped gently down, and the area around the tarpaulin turned steadily into mud.
We opened the traps one by one, gently picked up the Woodmice, identified them by the code marks clipped into their back fur, and weighed them. Identification is not as easy as it might sound, as mice wriggle, and the marks are not necessarily exactly where they ought to be. We’re also reusing the same codes for males and females, so we have to sex the mice. At least the males are generally larger, wrigglier and heavier, so a guess is likely to be right, but weights overlap and the external signs are not very different, mainly just a larger distance between the two openings in the males, unless the testes are big enough to give telltale bulges at the base of the tail.
Out of 20 mice caught, same as yesterday, 19 were recaptures, giving a population estimate in the trapping areas of about 21 mice by the Lincoln-Petersen capture-recapture method.
Of course there are plenty of reasons why the estimate might be wrong, not least that the animals which have been caught learn that the traps are warm, dry, safe, and full of nutritious food. They may, in short, have become trap-happy, getting themselves recaptured as soon as possible!
All the same, the high rate of recapture does suggest that the population is fairly static in the area, and not terribly large.
We have only caught Woodmice in the traps here. It remains possible there are Field Voles in the meadows, but we have few meadow traps, and only near the edges: and if there were voles here, their population would be low after the winter, so we’d not expect to catch many.
Vole Patrol hard at work! Coding (clipping fur patches), measuring, recording
I’m so cold! My feet are frozen! said Huma. It was indeed a chilly bright winter’s morning. We were grateful when the sun came up and warmed the glade where Vole Patrol had set up its measuring station, with tarpaulin, big sacks for opening traps, small bags for weighing and measuring, all the traps in order, scissors to code the animals’ backs, rulers, scales, fresh hay and three types of bait.
Mouse from M3 – hold still now
Unlike the meagre daytime catch of yesterday afternoon, 20 of the traps contained mice.
I had a go at measuring and coding; then Huma put a mouse back in the big sack, as if just out of an opened trap, and under her watchful eye I caught it gently by its scruff, transferred it to a small bag, and weighed it. I’m a mammal wrangler! The main difficulty, apart from their remarkable ability to escape, is that they hunch up, making straight-line measurements rather tricky.
Mouse from M2 – a female
Only one other trap had been triggered, so the false alarm rate was well down now: resetting the sensitivity of all the traps had been more than justified.
Wood Mice have big round ears
We were soon very busy: bringing in the full traps; opening them, catching the mice, coding their back fur, measuring, weighing, carrying them back to where they came from and releasing them.
Measuring and recording the weight
Tony the ecologist, who helped with the trapping today, said he’d expected Wood Mice rather than voles. Voles cannot easily make their way along railway embankments as they’re predated by Foxes and Badgers, which freely use railway “corridors”. Small isolated populations can easily die out, which is probably what happened here.
We approached the now armed and possibly triggered traps with some excitement. Of the six traps in “our” row C, four had been triggered. We picked them up, locked the other two so we wouldn’t catch any more mice while we were analysing the catch, and brought the four traps to Huma.
She opened trap C6 inside a large bag. A Wood Mouse shot out into the bag. I got a very blurry picture of a shadow behind the plastic.
Opening the first trap C6
Huma reached for the Wood Mouse. It bounced speedily up her arm, through the gap at the top of the bag, and hopped away over the tarpaulin. None of our other traps had anything in them. I must have looked disappointed as Huma told me there would be more.
Luckily there was: one of the meadow traps had caught a fine large male Wood Mouse.
It’s a BoyWood Mouse has a yellow patch on chest
We sexed, coded (A = clipped patch on left shoulder), measured body length and hind foot, and weighed the mouse. It wriggled quite hard and almost escaped, but Huma was quicker.
Mouse A’s fur is clipped on left shoulderMeasuring the hind footWeighing
Then we took the mouse, still in its bag, back where it came from and let it go. Likely it will feast on the plentiful bait in the warm dry trap again.
Out of 32 traps, 8 had triggered and 2 had mice in them, much too high a false alarm rate, so Huma reset their sensitivity for tomorrow morning.
The English seem unemotional … except for their passion for nature
