SardineCam

A couple of my trail cameras have been on tour - to my friends Gill and Martyn in deepest darkest Hexhamshire.  I took a new camera box for one camera and set up the second with a sardine lure as a new experiment.  Sardines are used by researchers to increase detection of carnivores so I wondered if it would work here.  Hexhamshire is home to polecats (Mustela putorius), one if the UK's most elusive mammals, so one aim was to see if we could catch one on camera.  The more realistic aim was to see what we would find.

The cameras were set for three weeks and at the end of that time both SD cards were full.  The sardine camera had 398 videos and the box camera 498 so I had plenty to look through.  The sardine camera was set up at the edge of woodland with the camera and the sardine can fixed to opposite ends of a piece of wood.  The can was secured with a cable tie.

SardineCam recorded 11 species but only four of those were interested in the sardine lure - the others were just passing by.  The four were badger, wood mouse, magpie and domestic cat.  The badger visited only once but tried hard to get into the can.  The camera gave a great close up of its teeth and claws (with a spider in the top left of the lens).

The magpie visited twice and the first time it managed to peck a few fragments of fish, even though the can was only slightly open (the can is now very visible after badger removed all my camouflage).

The wood mouse visited many times, obviously attracted by the smell but not trying to get at the can.  The cat just sniffed a few times and walked on.

Most of the 398 videos were of American grey squirrels.  Other passers by were blackbird, robin, wood pigeon, pheasant, roe deer, and red fox.

My new camera box was set up at the base of a stone wall.

It had large entrance pipes hoping to entice in slightly larger animals but in the end the only visitors were wood mice, bank voles, common shrews and pygmy shrews.  Here is a brief summary of 498 videos (most of which featured a wood mouse!).

It was very interesting to try out the cameras in a new environment.  The card in the  camera box was full in only nine days so another time I would need a bigger card.  I was hoping we might see a stoat or a weasel and I still have polecat on my wish list.

Developing WeaselCam

I have been experimenting again.  One of the limitations of the Mostela design of the trail camera box for weasels is that the two entrance holes are opposite each other and the weasel often dashes straight across in a blur.  It occurred to me that offsetting the entrances in some way might make visitors pause or look around so I built a new box.  This one is made from a very long under-bed storage box, the extra length giving more flexibility with the camera position.  The camera now looks straight down one entrance and the other is to the side, as before, with a small rock in between.  This is how it looks.

And this is a phone view of what the camera might see.

I have camouflaged the box a bit more than before so that it might look a bit more "natural" from a weasel or stoat's point of view.

It was no surprise that the first visitor to the new box was a wood mouse.  With the new view we are able to see it coming and going.  The third mouse seems to have the right idea.

Next up was a bank vole, good to see as there have been very few on the cameras in recent weeks.  The population is at its lowest at this time of year as quite a lot have been eaten by weasels, stoats, foxes, kestrels, owls, etc.

And best of all, within three days, a weasel, obviously intrigued by the new box.

This was one visit, all recorded within 40 seconds.  It is fun to see what is happening outside.

There is work to do on the camera position and angle, and perhaps a bit on the interior design, but I think it has promise.

Planning ahead for the coming summer, I have also greatly extended the weasel wall which is between the copse and the meadow.  Is is now higher than before and is 10m long.  The original had a nest box built into it and I have put in another one in the new extension.

This is made from a small Ikea storage box, a bit larger than a shoe box, with a weasel-sized entrance hole.  I have no way of knowing whether the weasels were using the original and the same will apply to this one which is now buried within the wall.  Robert Fuller, the source of inspiration for this, had lighting and live-streamed TV cameras in his but that is a bit beyond me. However, I will put up a couple of trail cameras in the summer to watch the wall like last year. This is how the new wall looks, built with lots of gaps and nooks and crannies.

And lastly a bonus video.  This camera was set up elsewhere to look for otters and recorded a frustrating near miss which was lucky all the same.   A weasel was hunting right at the edge of the frame and made a kill just out of view.  The main image is cropped and there is a more heavily cropped slow-motion replay ay the end.  You can just see the weasel roll briefly into view with the wood mouse it has just killed.

SmallMammalCam

This is National Mammal Week so it is a good time to show a few mammal pictures.  When I wrote about the small mammal camera box a few weeks ago it was about 5m inside the small copse in my garden.  The camera was seeing bank voles, wood mice and shrews every day/night.  After that I moved it about 10m, so it was now 5m into the meadow.  The clientele changed immediately and the wood mice stopped coming.  The bank voles and shrews still turned up regularly but the new arrival was a field vole.  The noise on the video is rain on the roof of the box.

The next video shows the difference between a bank vole and a field vole.  The latter is larger, greyer, has a shorter tail and has flatter, furrier ears.

Bank voles usually visit the box one at a time.  If there is more than one it can lead to a bit of conflict.

The other regular visitor was a common shrew.  It is hyperactive compared with the voles - the video is at normal speed.

I then moved the box back to the edge of the meadow and the copse and the wood mice immediately reappeared.  Being mainly nocturnal they show up in infrared recordings.

I was surprised that the mice don't want to venture even 5m into the meadow, and that the field voles won't go 5m into the wood.  The bank voles and shrews are happy wherever the box is.

The main reason for having the small mammal camera box is to try to film a weasel but so far no joy.  I have seen the weasel this week near the gate so I have moved the box over there and fitted larger entrance pipes in the hope that might entice it in.  We'll see.

Cohabitation

I noticed a hole in the ground at the edge of my meadow and set a trail camera to see what was in it.  I reckoned whoever was down there could be tempted into view with a few sunflower hearts.  The result was a surprise as there were three different species sharing the hole, presumably with separate living accommodation underground.

I guessed there would be a vole as the hole was connected to tunnelled runs through the grass. Most often the camera shows a bank vole, usually dashing out and back in but sometimes disappearing down the run.

Bank voles move fast, hoping that there isn't a kestrel or a weasel watching.  This was on a different camera with a bit of a green colour cast.

Next to show was a common shrew.  Despite being insectivores, shrews are also keen on sunflower hearts.

And then a field vole.  Not so easy to tell at first because it usually shows up at night, but it is larger than a bank vole with a shorter tail and larger flatter ears.

Here are the three of them at night, plus a less welcome visitor.

The camera usually records the animals one at a time but one day there were several confrontations between a vole (probably the field vole) and a shrew.  Several times the vole blocked the entrance and once it chased the shrew - I have added a couple of slow motion replays because the action is so fast.  The last clip shows the shrew eventually gets in when the vole (probably a bank vole this time) turns its back.

I think this type of cohabitation is not unusual.  A few years ago I put a camera on the entrance to a pile of stone in the copse and recorded bank vole, common shrew, wood mouse and water shrew all using the same entrance.

SmallMammalCam

This blog has been taken over by insects in the last few weeks so it is high time we had some trail camera images.  My small mammal trail camera box, modelled on a Mostela, has been set in the garden for over a month, hoping to catch a glimpse of a weasel or a stoat.  So far there has been no sign but smaller animals are daily visitors.  I put in a few sunflower hearts from time to time so the box will smell of mice and voles which may, in turn, tempt a curious weasel.

The most frequent visitors, especially in daytime, are bank voles.  They vary in size as some are not full grown.  The video shows a full size vole stuffing its cheeks with seeds before taking them off to eat in peace or to hide for later.

Wood mice are mainly nocturnal and so far have only shown up at night, so in black and white on the video via infrared.  They usually turn up long after the voles have taken all the food.

Common shrews are insectivores but they are surprisingly keen on sunflower hearts, something I have seen before.

Smallest of all are pygmy shrews.  Weighing only 5g or so they are slimmer than common shrews with a proportionately longer tail and with two-tone colouring rather than the three-tone of common shrews.

The last video puts them all together to compare their sizes.

2021 End of year review - Day 4

Day four of my end-of-year review.  This video was in a small mammal box I made for the trail camera.  Its main disadvantage is that the animals run along it towards the camera and very quickly go out of focus.  (The newer replacement sets the camera a bit farther away and the orientation encourages the animals to stay in focus.)

The main daytime visitors to the box were bank voles and these two were fighting over access to the food. Fortunately they are different colours so we can easily see which is which.

Pop goes the weasel

Ever since the weasel turned up in the garden in the summer I have been trying to get another picture.  Inspired by the Mostela*, a trail camera box used for monitoring stoat and weasel populations, I built one similar from a translucent plastic storage box (£7 from Dunelm).  There are two holes at one end and a trail camera at the other.  The Mostela was designed by Jeroen Mos, an ecologist and small mustelid researcher in The Netherlands, and is an enclosed box with a cutaway plastic pipe connecting the two entrance holes.  Wanting better pictures in a more natural setting, I made mine to admit natural light and built a small "stage set" of bark and loose bark chippings at one end.  The trail camera has a +2 dioptre lens to cope with the close focus.  It can record in colour in daylight but reverts to infrared when the light is poor or at night and it is then augmented by a motion-activated battery-powered infrared security light (a Brlnno APL200).  This is a view of the box with the lid removed.

Here are the camera and the infrared light.

This is the "stage set".

Here is the box in the garden with two Victorian land drain pipes as access tunnels.

Like other small mustelids, weasels are very inquisitive animals and will investigate any small hole which might contain prey.  For the first few days I baited the camera box with sunflower seeds so that it would smell of voles and mice but recently it has been left as it is (although mice and voles still visit every day).  I had the camera box set in my garden and the local nature reserve for four weeks before a weasel eventually made a brief appearance this week.  In fact it was very brief so I have added a 25% slow motion replay to the video.

Several other animals are much more regular visitors.  They include wood mice, always at night and so in black and white.  Wood mice visit every night and spend a lot of time in the box.  There is no food for them but perhaps it is warm and dry and feels safe.

Bank voles more often appear in daylight.  It is a pity the weasel didn't stay this long.

Common shrews also mostly turn up in daylight.  This clip also has a 25% speed replay.

Pygmy shrews appear both in daytime and after dark.

And a couple of very unexpected visitors.  Both birds were in the box for over two minutes and got rather agitated when they couldn't find the way out.

I plan to leave my weasel box set in the hope of more recordings and, perhaps, one day even a visit from a stoat.

* Mos J, Hofmeester TG.  The Mostela: an adjusted camera trapping device as a promising non-invasive tool to study and monitor small mustelids.  Mamm Res. 65, 843-853 (2020). https://doi.org/10.1007/s13364-020-00513-y

ShrewCam

The small mammal trail camera has been regularly recording shrews, along with the dozens of mice and voles, both in my garden and at the local nature reserve.  When I looked closely I realised that there were recordings of pygmy shrews as well as common shrews from both sites.

Compared with a common shrew (Sorex araneus), a pygmy shrew (Sorex minutus) is noticeably smaller; has a significantly longer and hairier tail; has two-tone colouring, lacking the paler flanks of the common shrew; and has a rather domed head and a thin pointed snout.  Some of these features are quite hard to pick out on a video, or even on frame grabs, because shrews move at such high speed.  The body weight of a pygmy shrew is 2.5-7.5g and of a common shrew 6-12g.  In the video I have added a bank vole (14-40g) and a wood mouse (13-27g) for comparison.

One advantage of the small mammal camera box is that the animals are all more or less at the same distance from the camera, making a size comparison easier.

In a still frame from the video, this is a pygmy shrew, showing the long tail in the first image.

This a rather blurred high-speed common shrew but you can see the size difference.

On the same scale this is a bank vole.

And a wood mouse.

Making progress with SmallMammalCam

I rebuilt the small mammal box, putting on a larger perspex roof and lining the box with bark, this in the hope that the animals feel more secure and the pictures look more natural.  There is a single small side entrance about 45cm from the camera.  I have tried the box out in the garden and in the local nature reserve and in the first week it has been busy with bank voles, wood mice and common shrews, all of which are keen on free food and enjoy exploring.

Bank voles will often sit and eat in front of the camera.  This one was stocking up, cramming as much as it could into its cheek pouches.

Bank voles don't like sharing.  In the end the paler vole was the one to return and carry on feeding.

Wood mice are mainly nocturnal so they usually show up only in infrared videos.  They are hyperactive and spend most of their time exploring the box.  This one paused for a munch on a mealworm.

It can seem crowded if there are two in the box.

At other times they tolerate each other.

I can recognise several individual mice.  This one is small.

Another is large with notched ears.

This one is missing half an ear and has a lot of scars, presumably from fighting.

Here's another very scarred individual.  I wonder if this was from fighting or if it perhaps escaped from an owl.

This one has a permanently curled tail.

And this one has a short tail.

Common shrews are smaller than mice and voles and can squeeze through tiny spaces.  There wasn't supposed to be a gap there but the shrew found a way through.  It instantly changes shape from thin to round.

And another brief glimpse of a weasel.  The reaction time of the camera is around 0.4s and in that time the weasel has already come right down to this end of the box.  It was gone in a flash so I made the video in slow motion.  After the weasel had gone nothing else visited the box for over four hours, even though the food was still there.  I expect they could smell danger.