CritterCam - the search for a water vole. Part 2

Following on from my previous post, this is the second report on my attempts to catch a water vole on a trail camera. The second camera was about 50m away from the first, the position of both cameras being determined by where I could get some field of view for them near water.  It was difficult because there was mostly just a trickle of water under the grass and rushes.  This was the position of the camera.

There were again plenty of views of voles but most were field voles. This time I used a 150mm cut section of reed as a calibration and unlike the piece of raspberry cane which was dragged off by the voles (I wonder what they did with it) the reed was ignored and stayed more or less in place.  Here are field voles near the reed.

Checking through the videos I did eventually see a larger vole.  Bank voles are 8-11cm long (head and body) with a tail 50% of body length, field voles are 9-11.5cm long with a tail <40% of the body length and water voles are 14-22cm with a tail 60% of the body length.  Obviously the young of each species are smaller.

Here is the calibration reed.

And here is the large vole with the same calibration line.  It measures about 14cm so it must be a water vole.

Unfortunately it doesn't show its tail on the video so we can't use that to check but it is too big even for a large field vole.  As you can see on the video it dragged the apple away and didn't show itself again.  At the start of the video a small vole dashes across, perhaps a bank vole or field vole.  The last clip is a very brief glimpse of a larger vole three days later.

So that is all I saw, not quite as exciting a video as I was hoping for.  There were lots of other brief views of small voles, which could have been bank voles or field voles or young of either species and more brief views of common shrews, wood mice and meadow pipits but once the apple had been dragged away there was nothing to tempt the voles out into view again.

I plan to have another attempt to get better water vole pictures next May when I am up there again.  I may try slightly lower down the stream in the hope of finding a bit more open water and a clearer view.  I think I'll also use larger pieces of apple so they don't disappear so quickly and perhaps fix them so they can't so easily be dragged into cover.  After the excitement of finding three shrew species on the other camera I may put down bait for shrews as well.

Water voles are widely but sparsely spread in this country and are rare in Northumberland.  The map shows sightings reported to iRecord in the last 20 years, indicated by small blue squares, mostly around the rivers South Tyne and Allen in the south west of the county.  This site (red arrow) is about 10km north of the South Tyne and 20km south-east of Kielder (green arrow).

The water vole is one of our most threatened mammals, having lost about 95% of its former sites and being classed as "endangered" on the Red List.  The population decline has mostly been caused by predation by American mink with loss and fragmentation of habitat as additional factors.  In an effort to reverse the decline the Northumberland Wildlife Trust has organised a water vole reintroduction programme - Restoring Ratty.  Since 2016 over 1600 water voles have been released around Kielder in the far west of the county.  Donor animals were collected from the North Pennines, Yorkshire and Scotland and taken to Devon for a captive breeding programme.  The offspring are brought back north for release around Kielder Water.

Kelly Hollings, Northumberland Wildlife Trust's Project Officer in the Restoring Ratty project, says that the released voles have migrated from their release sites to smaller streams and ditches so more recent releases have been in such places, perhaps similar to the one I have been investigating.

The site I have found is between the Kielder release site and established populations farther south.  With luck (and hard work by the Wildlife Trust) water voles will continue to spread and different populations will link up.  This experience also shows that in wilder parts of the country there may be a few more about than are known.

CritterCam - the search for a water vole. Part 1

This all began in May, when I was doing my bird count near the Wark Forest for the BTO Breeding Bird Survey.  At one point I glimpsed a small mammal running across the track out of the corner of my eye.  It was dark, vole-shaped and rat-sized so I wondered if it could be a water vole.  There is a very small stream running through a pipe under the track, no more than 300mm in diameter, and because of the dry spring weather there was almost no water flow.  The habitat is poor unimproved wet grassland with mostly rushes rather than grass at that point, not a habitat I associated with water voles.  (I used to see them 50 years ago in a slow-flowing lowland river.)

Although the BTO BBS records mammal sightings I wasn't confident enough to record a water vole.  I did, however, send a message to Kirsty Pollard, a water vole expert at Durham Wildlife Trust and she passed my email on to Kelly Hollings, Northumberland Wildlife Trust's Project Officer in the Restoring Ratty water vole re-introduction project in Kielder.  Kelly was very encouraging and said the habitat was good for water voles, similar to some of the release sites in Kielder, so I went back with three trail cameras in July.  The cameras were in for a week, one close to where I thought I might have seen a water vole and two on a slightly larger but still very small stream (<500mm across) a couple of hundred metres away.  They recorded hundreds of videos and on a first look through I couldn't see much very exciting.  There were lots of glimpses of small mammals and I could identify field voles and wood mice, as well as reed buntings, meadow pipits and a roe deer's ankles.

Before giving up I had another look through the videos and could pick out a few where the voles looked bigger.  They were all on the on the trickle of a stream where I had my first sighting and there was very little on the other cameras.  It is difficult to judge scale although there is a slice of apple visible in the first clip.  I sent a very brief extract to Kelly and she replied that she was 99% sure it was a water vole.

So I went back earlier this month with two cameras and put them both on the first stream.  In most places it is difficult to see any water at all as it runs underneath the vegetation.  I spent time clearing a view and making sure the apples were better positioned.  Between them the cameras recorded almost 700 video clips so it is taking a while to work through them.  The first camera was set up here.

There are plenty of images of voles but I think they are probably all field voles.  Bank voles are 8-11cm long (head and body) with a tail 50% of body length, field voles are 9-11.5cm long with a tail <40% of the body length and water voles are 14-22cm with a tail 60% of the body length.  On the video it wouldn't be easy to tell a field vole from a bank vole or a juvenile water vole without seeing the tail but in some images the tail is clearly visible and is short.  (The other name for a field vole is short-tailed vole.)  The first two voles in the video are small whereas the last one which appears briefly nearer the camera looks larger although it still clearly has a short tail.

I also put a piece of raspberry cane next to the apple, 150mm long to act as a scale but the voles didn't approve of my measuring stick and moved and then removed it.

One very interesting sighting was of three shrews - water shrew, pygmy shrew and common shrew.  You can see that shrews don't eat apple but they are very curious (and very fast).  To find all three species in the same place on the same night was a pleasant surprise.

There are another 390 videos from the second camera so I'll report back soon on those.

Cucumber green spider

A spider has featured on this blog only once before.  This little beauty is a female cucumber green spider, Araniella cucurbitina.  It weaves a small orb web in a bush or hedgerow and sits in the middle of the web, relying on its camouflage for protection.  The female is about 8mm across and the male is half that size,

This one had built a nest in the protection of a leaf curled over with silk.

Here she is spinning a silk thread and controlling it with a hind leg.

When last I looked there was second clump of eggs surrounded by silk and the spider had moved on.  Freshly emerged spiderlings are red and they change to brown in the autumn. 

The buck stops here

For some reason roe deer always seem to be a bit bigger than they really are.  I suppose we usually see them in woods or fields without an accurate sense of scale.  It is only when they stand next to something we can appreciate that they are about the size of small sheep.  I saw this handsome buck when I was out looking for dragonflies in Gosforth Nature Reserve.  I don't know why he didn't see me as I was in the open, just the other side of the pond.

As he went up the bank he passed a tree guard to give a sense of scale.  Roe deer are very keen to browse on newly planted trees so we use thousands of tree guards every year as we replant the woodlands in the reserve.

I was downwind so I don't think he ever knew I was there, despite the clicks from the camera.  After posing for a few moments he wandered into the woods.  I was able to get the measure of a roe buck once as it stood next to my gate post.  To the tip of his antlers he is 1m tall.

* "The buck stops here" is a phrase used by US president Harry S Truman.

Out and about in July

I haven't been able to get out and about so much this year, for obvious reasons, but I went on a small expedition on the last day of July to Slipper Tarn, a small acidic pond surrounded by tall trees in the National Trust's Cragside Estate at Rothbury.  It is a good place to see dragonflies and there were hundreds on the wing on the hottest day of the year so far.  The most numerous by far were black darters and you can see how small they are from this immature male on my hand.

This is a mature male.

A newly-emerged female.

And a mating pair.

I could see lots of patrolling male hawkers but they were flying incessantly in the heat.  I didn't manage a single photo of a southern hawker but did find this pair of common hawkers in deep shade in a rhododendron.

I saw at least half a dozen other mating pairs but they mostly flew high into the trees out of sight or out of the range of the camera.

One surprise was seeing lots of large red damselflies as they seem already to have disappeared from ponds closer to home.

Earlier in the month I saw a pair of mating emperors at Banks Pond, the second time in three weeks and the second time ever.

Common darters are now very common

and I have seen a few ruddy darters.

I keeping promising myself that I won't get too interested in hoverflies but some of them are quite striking.  This one is another bumblebee mimic, a male Eristalis intricaria.

This one is a female Volucella pellucens.

And this one is a female Xylota sylvarum.  All three IDs confirmed by the kind folks on the UK Hoverflies Facebook page. 

On another expedition I went looking for a golden-ringed dragonfly but didn't find one.  I did find some butterflies including a comma,

a small pearl-bordered fritillary, the first I have ever seen,

a small tortoiseshell,

and dozens of ringlets.

The last two times I have been to Banks Pond there has been only one adult swan and only three cygnets.  I think the missing swans have been predated as there were a lot of feathers around and the surviving adult looked sad and was letting the cygnets swim around on their own.

Fox and cubs

Last night was the first time I have seen two cubs together this year.  Mother and the short-tailed cub were here as usual when I spotted another fox sitting in the shadows.  It was a second cub and although it moved into the light it didn't come for food.  I managed only these three photos before the vixen moved off, taking the second cub with her.

The short-tailed cub is here every night and prefers it when it has the food to itself.

The dog fox is now fairly intolerant of the cub, which is learning to keep its distance.  The dog had been in the wars again this night but as the injury is on his shoulder it might be just a scratch rather than a bite.

The cub does still try to creep in for some food

but is likely to get snapped at.

The father's tail is a warning.

The cub's tail tries to respond but half of it is missing.

The vixen turned up a few minutes later.  Her posture (low, ears flattened, lashing tail) is very submissive.  The video is a bit amateurish but it does show the interactions between them.  There is no sound because of the double glazing (and the radio was on in the kitchen!).

The foxes usually turn up after dark but are sometimes earlier.  The vixen is usually here first.  Here she is seen from the kitchen window by the iPhone, with my attempt at a meadow and the copse in the background.