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.
At quarter to seven this morning we wrapped up well against the cold, on a beautiful clear day, the crescent moon glowing in the southeastern sky, and gathered at the hut. After a welcome cup of tea, we picked up haversacks full of boxes of bait balls, a little bag of apple slices and another of maggots, and a rubbish sack. We trooped off down the reserve to inspect the traps arrayed around the wood, meadow, and pond.
Was there a mammal in here? Inspecting one of the Waterside traps
A Song Thrush sang loudly and beautifully from the Willow Carr thicket.
Bait Taken from Meadow Trap
In the anthill meadow, trap M3 showed unmistakable signs of a mammal visit spilling from the entrance.
Did we catch something by mistake?
Another of the meadow traps caused a flurry of excitement. The trapdoor was up! Had we somehow caught a mammal, despite checking that all the trapdoors were locked down? Huma carefully opened the trap in a large plastic bag to prevent escape. There was nothing inside. Probably the trap had been left with the door closed.
Making Bait Balls
Back in the hut, still with surgical gloves on, we mixed up more bait and rolled it into balls. The little boxes that protect the bait balls in the haversacks are on the table.
It was cold out today, and I was glad of fleece, warm coat, woolly hat and gloves — not to mention gumboots through the clogging mud, the worst I’ve seen in many walks at Wraysbury Lakes.
But when the sun came out, it was beautiful, and I hope I’ve captured a little of that wintry beauty for you (and some of the puddled paths) with this photo of last year’s dried-out Teasels.
Just as I was about to take the photo, a flash of white from two largish finches caught my eye, and I grabbed my binoculars. Luckily, they landed in a bare thornbush, and showed themselves to be a male and a female Bullfinch, their black caps, red chests and white rumps splendidly visible as they sat a while, occasionally leaning right forwards to peck at the buds. They flew off to another bush, giving me the best views I think I ever had of the male/female differences at rest and in flight. The male really did glow red.
Up on the horse hill, a flock of some 50 Goldfinches flickered overhead. A Green Woodpecker called in the distance, as did two Mistle Thrushes, their loud, monotonous, ringing cries carrying across the wet ground. A solitary Redwing was all that was left of the winter flocks. Two streaky brown Linnets flew across.
A cormorant flapped heavily overhead, quite goose-like in front view but obvious enough in outline as it went by. Down at the nearly birdless lake, 5 Goldeneye brightened up the view, with a few distant Shoveler.
Science proceeds in slow steps, and things far more often become clear gradually than in dramatic Eureka! moments.
After “hours of fun” trying to decipher sheets of paper covered in a mass of footprints, we learnt that most of what we had seen were mouse/vole (indistinguishable as prints), squirrel, cat, and rat. Some of the West London survey sites in London Wildlife Trust’s Vole Patrol had evidence of other mammals, from camera trap shots of foxes and badgers to a fuzzy glimpse of an elusive otter.
Not a Yeti! Double prints of a cat giving a 5-toed look
Huma had been busy visiting all the sites, teaching volunteers, getting people to build mammal nestboxes (like birdboxes, but with the opening round the back!), and inspecting a lot of shrew tubes and sheets of paper covered in footprints.
The five-toed “Yeti” footprint turned out to be a cat (notice the streaks from its furry feet) which had placed one four-toed foot almost in the print of another, so there are two heels of the hand and the middle three toes double-printed. Of such are mysteries made.
Camera trap in position
We all enjoyed looking at what the camera traps had caught. The video clips were much easier to interpret than the still images. Several small children had crept up to the cameras and spent a while peering into the lenses (What? Me? I’m on camera?). Two foxes cavorted with long bushy tails. A badger ambled past like a crotchety old gentlemen on the way to his club. Mice with big round ears, surely wood mice, bounced and scuttled in and out of the field of view: sometimes only the glint of their eyes revealed their presence, and sometimes even that was very small and only at the edge of the frame.
Then we cleared an easily-wiped formica-topped table for … shrew poo analysis. We had up to ten baited tubes from each site. With surgical gloves, dissecting probes, tweezers and hand lenses, we carefully emptied each tube into a Petri dish and looked for mammal pellets. Mice eat seeds and produce solid, compact pellets, round one end, pointed the other. Shrews eat insects and produce pellets of a similar shape, but made of non-stick fragments of insect cuticle, so their pellets tend to crumble. Many of the tubes contained nothing; one or two had been lost in the field; several contained mouse pellets, most likely wood mouse; a few seemed to contain shrew pellets. We dropped the pellets into sealable inch-long plastic tubes labelled with their site, the date, and the shrew tube number, and recorded what we had found in the logbook, to much cheerful banter.
Mammal nestbox: Yes, the hole is meant to be on the back
It will become much easier to determine which wood contains which mammals when we start trapping in a fortnight’s time. Then we have to get up and be at the reserves by 6:30 in the morning for a two-hour stint, to be repeated in the afternoon. My family will be amazed if I manage any kind of early morning.
Here in town, the daffodils are in bloom, the bluebells are coming into fresh green leaf, and the temperature is 10 C, so it might almost be early spring. And this morning I heard the chi-chi-chi / zheeeee! of a singing male Greenfinch, getting into the spring courtship season. But some trees on the same common are full of twittering Redwings, winter visitors from the frozen North, a cheerful and bright winter sight.
Out in the countryside, it looks much more like Winter, the trees as bare as they ought to be in early February, the only flowers a few tufts of snowdrops near the pleasantly lichened reserve signboard at RSPB Otmoor. The reserve has grown steadily better from its early day, with more and more wet scrapes, pools, and reedbeds spanning something like a mile of Otmoor’s wide, flat expanse.
A Kestrel hovered overhead; Bramblings and Chaffinches lurked in the hedges; Redshank called in the distance. Red Kites drifted by over the trees. Seven Snipe jumped up, screeching, from wet grass and zigzagged to a muddy island. A Cetti’s Warbler sang from almost under our feet, invisible.
The luxurious hide revealed numbers of Wigeon, Shoveler, and Teal, and a flock of Linnets with a few Goldfinches feeding on the grass in full view. Yellowhammers, Reed Buntings and more Linnets sat in the bushes. The trees were full of twittering: I soaked up the soundscape with hands cupped to my ears.
Thousands of Golden Plovers (and some Lapwings below)
When a Buzzard came over, some 3,000 Lapwings and a similar number of Golden Plover got up, all glinting gold as they turned together in the sunshine.
Golden Reedbeds from a hide with no roof
Over to the north, a Marsh Harrier dropped into the reeds, got up again and scoured the reedbed for signs of prey, its broad brown wings slightly raised, its broad tail quiet unlike that of the Red Kite that wheeled past it.
Huma Pearce, mammal expert, in Gunnersbury Triangle
The hut in the Gunnersbury Triangle Nature Reserve, which is managed by London Wildlife Trust, was buzzing with excitement. It was packed full of people on a bitterly cold winter’s day, everyone eager to find out how to map London’s mammals.
You might think that in a metropolis of some ten million people, pretty much everything would be known by now about the city’s wildlife.
But that’s not so. A quick look at the existing maps of some of our mammals – from field vole to otter – tells a simple story. Hardly anything has been published about what lives where in London.
The field is wide open for new discoveries, and those are what we hope to make in the next year as we track down those voles, and maybe some larger animals into the bargain.
London Wildlife Trust has secured £97,000 from the Heritage Lottery Fund to study the distribution and abundance of small mammals in 9 woodland sites in West London. Although the focus will be on small woodland mammals, Huma (the mammal expert employed to co-ordinate and deliver the surveys) also hopes that with the help of volunteers she will be able to collect mammal data from a range of sites of different sizes, scattered across the boroughs of Hounslow, Ealing, Hillingdon and Harrow.
On each of the 9 woodland sites, the project will need to find out which species are present, and to estimate their numbers. But small mammals are shy, inconspicuous and mainly active at night. Tracking them down isn’t easy.
So Huma is getting together and training a “Vole Patrol”, a small army of volunteers, keen to get down and dirty with wildlife. That means us! We need to know how to collect data on the mammals, without hurting them, or disturbing them more than absolutely necessary. That means training.
The first thing you might think of is live trapping, and we’ll do some. Huma showed us a Longworth trap, a light aluminium contraption made of two boxes that lock together. You put some food and bedding inside; a trapdoor falls when little feet venture inside.
But small animals particularly shrews need food all the time. You have to visit all your traps after six hours, to ensure that any animals captured are safe, and to identify the species before they are released. We’ll do some trapping later in the year.
Numbering a hedgehog tunnel
We’re starting, instead, with some baited hedgehog tunnels. Hedgehogs are hibernating at this time of year, so we don’t expect them, but the design is proven, and good for a variety of small mammals too. We assemble them from Correx sheets, like cardboard only waterproof. We fold them into a triangular tube, with a fourth side as an overlap, which we stick down with Velcro. Another sheet of plastic slides inside as a tray.
Clean paper, wet paint, food, paint, paper to slide into hedgehog tunnel
We stick a plastic dish in the middle, and fix masking tape both sides to hold some paint, which we mix up from non-toxic carbon powder and vegetable oil. At either end we pin down a sheet of paper. The dish is baited with special ‘Hog’ biscuits and dried mealworms: it almost looks appetising.
Hundreds of footprints!
We hide the hedgehog tunnels away from likely disturbance. The next day, sure enough, hundreds of footprints are spattered all over the sheets. The small ones are surely mice or voles; the larger ones not so easy to guess.
As well, there seem to be marks of tails dragged through the paint. We have to repeat the process every day for five days, with each tunnel.
Other volunteers will do the same in each of the other survey sites.
As well as the hedgehog tunnels, we take out a boxful of nest tubes. They’re made of yet more Correx sheet formed into square tubes, each with a simple wooden tray that slides in and out; the back is closed with a square of wood.
Fixing a nest tunnel into position
These were to be laid out in a rectangular grid. Easier said than done in a tangled, muddy wood! We push through the brambles, trying not to create more paths than we had to, looking for low branches out of sight of the paths, where we could tie on the nest tunnels. Then we recorded their positions with GPS. We’ll go back later in the year to see which of the boxes have been used.
We also put down some plastic tubes baited with mealworms, low down near a pond, for water shrews to visit, and perhaps to leave a few tokens (in other words, shrew poo) to indicate their visit. Species can be broadly identified from their droppings, but Huma is hoping that we might be able to get these, or little tufts of fur, analysed for DNA to prove which species was responsible.
Cherry Stone opened by vole in Gunnersbury Triangle
We can find out about mammals in other ways too. Different animals open nuts and cherry stones in their own ways: squirrels snap them roughly in half; mice nibble a neat round hole; voles bite into the shell more irregularly. We found a cherry stone near the first hedgehog tunnel: a small mammal had gnawed an irregular hole with sharp tooth-marks along its edge.
A Camera Trap in position for any small mammals in the grass
A glimpse of small mammals can be gained with camera traps, as seen on TV nature documentaries. You tie them onto a tree, overlooking a likely mammal run, and with any luck you’ll see mice, or voles, or who knows, maybe a weasel or an otter. London’s mammals are about to become a lot more famous.
Huma is keen to involve as many people from the local community in the project. So, if you would like to volunteer on some mammal surveys, I suggest you contact her by email: hpearce@wildlondon.org.uk
After the bitter cold of the New Year, down to a surprising -12C in London, suddenly spring (as it were) is back in the air, and the Daffodils are resuming their progress towards full bloom in gardens and on roadsides.
The warmth and sunshine tempted me out to Wraysbury. With the heavy rain and perhaps also the rapid changes of temperature, a large Poplar had fallen across the river, forming a minor weir.
Muntjac print
On the path, a Muntjac deer had left its tiny prints in the soft mud. Unlike a lot of other mammals, at least this one is readily identifiable from its print, the two small sharp slots of its slim feet not mistakable for anything else.
The lake, which had been full of birds as big as Swans last time I visited, was almost empty: a few Coots, some Great Crested Grebes, a Black-Headed Gull, a few roosting Cormorants, a few Tufted: and happily two of the area’s specialities, three pairs of Goosander, and nine Goldeneye (including three males).
A Kestrel hovered and dropped slowly after a small mammal in the long grass. A Redwing flickered away around a corner. A Song Thrush sang sweetly from a thicket. One or perhaps two Bullfinches gave their distinctive “Deu” call from the middle of a bush. Half-a-dozen Fieldfares chattered and skittered about from the top of one bare thornbush to another. A few Wood pigeons and Crows looked out warily.
The English seem unemotional … except for their passion for nature
