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.