Tag Archives: Vole Patrol

Vole Patrol reprise: visiting nest boxes

26 May 2016 Ian Alexander

Huma and John on Vole Patrol with Mammal Nest Box Perivale Wood — 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 It seems another world: bare leafless trees over chilly wet forest floor have been replaced by a thick green mantle over a mass of brambles that seem to have shot up faster than tropical bamboos and bananas (my father maintained that he could watch a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 I’m not certain I understand how a nut can be withdrawn through such a little hole.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 — 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.

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.

Conservation, Love of Nature, Natural History, Nature Reserves

Roe Deer at Fray’s Farm Meadows SSSI

13 April 2016 Ian Alexander

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.

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.

A few butterflies flitted about – Brimstone near the brambles, a Meadow Brown or two, several Peacock.

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.

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.

Conservation, Natural History, Nature Reserves

Vole Patrol 10: Gutteridge Wood Voles!

24 March 2016 Ian Alexander

Huma happy with first Field Vole in hand

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, 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.

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!

Gutteridge Wood Huma picking up trap by pond — 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.

Vole Patrol 9: Perivale Wood (Selborne Society)

Natural History

Vole Patrol 9: Perivale Wood

14 March 2016 Ian Alexander

The first cycle of trapping at Gunnersbury Triangle has been completed, and the action has moved on to Perivale Wood. This beautiful reserve is owned by the Selborne Society, the oldest nature conservation society in the world, founded in 1885 and thus a few years older than the RSPB.

Despite its name, Perivale Wood includes pasture (for horses), damp scrub, secondary wood on disturbed land, some hedges (we saw one newly “laid”, the trunks almost cut through and fastened at an angle with beautifully-woven withies), three ponds and two streams.

This, of course, enables London Wildlife Trust‘s Vole Patrol, by agreement with the Selborne Society, to search for small mammals in woodland, by water, and in meadow.

Walking in, we heard a Song Thrush, and much calling and drumming of Greater Spotted Woodpecker and Green Woodpecker. From the bare Oak trees of the photo above, I briefly heard an early burst of song from a Chiffchaff, my first of the year.

We met some new Vole Patrollers, including Lindsey, seen here acting as “scribe” for the all-important data, and Nicola, seen here weighing a Wood Mouse.

Nicola weighing a woodmouse — Nicola weighing a Wood Mouse

The team quickly sorted itself out, everyone sharing the necessary roles – fetching traps, opening them, weighing, measuring, sexing and coding the mice, recording the data, returning the mice to their exact locations, baiting the traps, and returning them to their locations. It’s not really complicated, but there is enough to do, and with over 30 traps in the different habitats around the reserve, each task has to be done many times.

Vole Patrol in Perivale Wood. In the distance, team members are fetching traps. In the centre, a trap is being opened inside the large bag,for the catch to be weighed and measured. In the foreground, a mammal is being coded before release. And behind the camera, a team member is recording events!

Conservation, Natural History

Vole Patrol 8: Capture-Recapture

10 March 2016 Ian Alexander

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.

Conservation, Natural History

Vole Patrol 7: Massive Morning Catch!

7 March 2016 Ian Alexander

Vole Patrol coding measuring recording — 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 — 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.

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.

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.

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.

Conservation, Natural History

Vole Patrol 6: First Catch

6 March 2016 Ian Alexander

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.

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.

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 shoulder — Mouse A’s fur is clipped on left shoulder

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.

Conservation

Vole Patrol 5: Woodmouse Woz Ere

5 March 2016 Ian Alexander

See Vole Patrol 4: Baiting not Trapping

I stumbled out of bed a bit late this morning and only just arrived in time to join the Vole Patrol team. The good news was some sunshine, birdsong (Song Thrush the highlight, with Great Tit, Robin, Dunnock, Long-Tailed Tit) for the dawn chorus, and proof from many of the traps of mammal activity.

Without wishing to get too scatological, a Wood Mouse laid some definitive, er, evidence of its presence on the door of this trap, which does bear an uncanny resemblance to a miniature toilet. There are actually 2 mouse droppings (the other one is on the hinge) in the photo.

It’s a mouse dropping, not a shrew’s, as shrew poo contains so many shiny, slippery insect cuticle fragments that it tends to fall apart, whereas these pellets have the solid consistency of a mouse’s diet of seeds.

Huma mixing bait (photo Joanne from Grow Chiswick)

Other traps had had their bait balls eaten (but not the maggot larvae, which shrews would prefer); some had bait crumbs outside their entrances, and others had leaves dragged inside, as if to make a nice warm nest.

Jo took these fine photos a day or two ago. I seem to have enjoyed labelling those traps!

Conservation, Natural History

Vole Patrol 4: Baiting not Trapping

4 March 2016 Ian Alexander

See: Vole Patrol 3: Baiting Traps

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.

In the anthill meadow, trap M3 showed unmistakable signs of a mammal visit spilling from the entrance.

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.

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.

Conservation

Vole Patrol 3: Baiting Traps

3 March 2016 Ian Alexander

See Vole Patrol 2: Shrew Poo

Today we began a week of intensive trapping. Huma wants to survey the small mammals now, before there is any risk of catching pregnant or nursing mothers. So we are going to put out and check traps every morning and evening.

The traps we’ll be using are a new design of tube trap. They are less fiddly than the old aluminium Longworth traps, and a lot cheaper too. Huma thinks they’re “volunteer proof”: we wonder. Being plastic, they are warm and comfortable for the mice, voles and shrews we hope to catch.

We learnt what to measure, and the distinguishing features of the species that we may see. Huma explained how we would set out the traps, in a grid of three rows of six traps (so, A1 .. A6, B1 .. B6, C1 .. C6), evenly spaced in the woods, with four more up in the trees (T1.. T4), five in the meadow (M1 .. M5), and five near water (W1 .. W5).

Each trap has two parts, so I painted its name onto each half.

We grouped the labelled traps into neat carrying trays.

While I was painting, the others rolled chicken feed, peanut butter, seeds and water into bait balls.

Then we put a handful of clean hay, a bit of apple, a bait ball, and a sprinkling of frozen maggots into the round end of each trap, armed the trap, locked the door open, and clicked the two halves together. The first two days and nights we don’t want to catch anything, but to accustom the mammals to visiting the traps.

We lined up in the wood, carefully set down the traps along natural edges, and marked their positions with hazard tape.

We have to visit them at 7am tomorrow morning…

ObsessedByNature

Tag Archives: Vole Patrol

Vole Patrol reprise: visiting nest boxes

Roe Deer at Fray’s Farm Meadows SSSI

Vole Patrol 10: Gutteridge Wood Voles!

Vole Patrol 9: Perivale Wood

Vole Patrol 8: Capture-Recapture

Vole Patrol 7: Massive Morning Catch!

Vole Patrol 6: First Catch

Vole Patrol 5: Woodmouse Woz Ere

Vole Patrol 4: Baiting not Trapping

Vole Patrol 3: Baiting Traps

The English seem unemotional … except for their passion for nature