Bad news if you are a water shrew that is, but maybe good news if you are a heron. The trail camera saw two shrews being eaten by a heron last year and another a few weeks ago in a blog I wrote for the Natural History Society of Northumbria. Then last week the heron(s) caught and ate nine water shrews in six days at only one camera position. I thought water shrews were uncommon but there must be a healthy population to sustain that level of predation. Or at least there was.
And a bonus heron video. Last month I posted a video of a heron that caught a frog that put up a good struggle and eventually got away, probably not unscathed. This time the heron caught a toad. The toad's defence is to swell up and produce a foul-tasting and perhaps toxic secretion from its back. The heron seemed to realise pretty quickly and dropped the toad before trying to wash the taste away.
After that I think the heron will stick to water shrews, while there are any left.
It seems that shrews are like London buses - you wait ages for one and then three come along all at once. WeaselCam is mainly seeing wood mice at the moment but a few nights ago there were three shrews. First a pygmy shrew, which has been appearing from time to time, then a common shrew, which hasn't been common recently, and last a water shrew, the first I have seen since September.
This has happened twice before. In 2020 I set a camera hoping to find a water vole up near Wark Forest and found three shrew species in one night. And a few weeks ago I saw three within an hour near Riding Mill. I don't know if these episodes have just been coincidence or whether the shrews could be following each other around or interacting in some way. Either way it seems odd. I posted the video on the Mammal Society Facebook page asking the same question but didn't get a reply, just lots of "likes". If you have any thoughts please leave a comment.
WeaselCam has been on tour a few times this year but has failed to record a weasel away from here. It has, however, been good at recording other small mammals. While in Williwood, the home of Denise & Phil, the box was visited by three species of shrew within an hour, providing an opportunity to compare their shape, body size and tail length. From the top they are common shrew, pygmy shrew and water shrew.
Here's the video.
And here are the three individual species - common shrew,
The trail cameras get a lot of "non-target" captures, mostly birds. At this time of year it is mainly robins, blackbirds and moorhens but earlier in the year there were plenty of ducks, geese and swans. They rarely do anything interesting so I don't save the videos but every now and then something interesting turns up. Herons do appear on the camera occasionally, but usually much too close and out of focus. This time two cameras were watching to see a heron catch a water shrew.
Notice a second shrew running along the bank and then making a quick exit when it sees the heron.
There was a second video a few days later which I am surprised to find I haven't posted before. Somehow the heron knew there was a water shrew behind the tree and caught it. It still had to bring the shrew down to the water to dunk it and make it easier to swallow.
This was probably the biggest surprise of the year. I had been putting dead field mice in the camera box for the weasels to collect and hiding them under a slate to give the camera time to react. In late August a water shrew appeared and stole the mouse. The mouse is as big as the shrew and the slate is much heavier.
As far as I can make out this was the first time a water shrew taking carrion had been recorded on video (ever, anywhere!). The shrew was a daily visitor for almost a month and then disappeared.
Two of my cameras have been on tour again, this time to Denise and Phil near Riding Mill in South Northumberland. As before, one camera was set up with a sardine scent lure and the other was in a camera box. SardineCam was set in woodland edge for the first week and within woodland the second week. It recorded 1061 videos in all, most of which were of wood mice. As last time, the mice were fascinated by the sardine smell. A domestic cat also came by to sniff but the highlight was a roe doe.
Passers-by taking no interest in the sardines were fox, American grey squirrel, robin, blackbird, song thrush and wood pigeon.
The camera box was set at woodland edge in the first week and recorded 546 videos, almost all of wood mice. In the second week I put it in a rough grass field, still not far from woodland. This time there were only 163 videos and almost all were of shrews - common shrew, pygmy shrew and, most excitingly of all, a water shrew. There is a small garden pond nearby but the nearest large pond is 160m away across a railway line. Here are the three shrews in frame grabs from the video to compare their size, body shape and tail length, common shrew above, pygmy shrew middle and water shrew below.
And here is the video.
It was fascinating to find another water shrew away from water, so soon after the one in my garden. Here is a montage of more water shrew action, all high speed.
If anything the common shrew is even more frantic. It was interesting to see it collecting the sunflower seeds I had put in. Shrews are insectivores but water shrews and common shrews both take sunflower seeds in my garden.
The smallest of the three, the pygmy shrew, seems a bit less hyperactive.
We did get a glimpse of a vole but it was very shy and didn't venture past the entrance pipe. I can't tell what it is with any confidence but from its size I suspect it is a field vole rather than a bank vole.
So no mustelids, which we were hoping for, and no wood mice in the field, but it was great to see all the shrews. And it is fascinating that moving the camera 50m from woodland to grass completely changes the clientele. I am not sure it will be worth persevering with the sardine lure but the camera box seems by far the best way to see small mammals.
The recent changes in the camera box ("weasel box" as was) are intriguing. The water shrew first turned up on 30th August and it has been here almost every day since. The last weasel sighting was 10th September and since the weasels stopped coming the common shrews and wood mice have returned. Until now I have never seen more than one species at a time but this happened twice on one night, a few hours apart. It is pitch dark of course, and the shrew doesn't have such good eyesight. The second time they must have passed each other in the entrance pipe before the mouse turned round and came back in.
Most days I feed the shrew with casters (blowfly pupae) and she usually takes them away one at a time. Occasionally she eats in, rather than having a takeaway. On this night she ate them all in the box, taking each one to the entrance and eating 28 casters in less than 20 minutes (I haven't shown them all), squeaking excitedly all the time. She certainly looks well fed.
There was a bank vole in the mouse trap in the attic so I put it in under the slate and the shrew took it, like she took the mouse the first time. She puts a lot of effort into retrieving her prize.
Shrews don't live through a second winter so this one doesn't have long to go. I am still hoping she might appear on camera with some of her offspring.
It is a week since the water shrew turned up in the camera box and took a mouse I had left for the weasels. The video caused a lot of interest on the Mammal Society Facebook page with speculation that she is still feeding young. The shrew came back an hour later, and again that night. The video shows her searching by smell in the dark.
She was back again on the following two mornings so I put out another mouse and she took that on Sunday night.
Since then I have had no more mice so I have been leaving casters (fishermen's casters, blowfly pupae) which I had in the freezer, as you do. And as fast as I put them out the shrew takes them away.
The shrew comes back twice a minute (I edited out the gaps in the video) so her nest or food cache can't be more than 12s travel time away, so only a few metres. I set another camera outside to see where she goes but she moves so quickly that it doesn't pick her up. Water shrews give birth to several litters up until August so I reckon this one will have young close by somewhere. I'll keep feeding in the hope that the youngsters will turn up on camera as well.
One interesting thing is that there have been only two weasel visits in the week since the shrew first appeared, compared with previously about two a day on average. I don't know if that is just coincidence or if the weasels would be put off by the shrew. That seems unlikely - I would have thought the weasel would be a threat to the shrew.
Wow. This is the most surprising find on trail camera so far. I have been putting a mouse in the camera box about once a week and until now all the mice have been taken by weasels. And then this. Yesterday a water shrew pulled the mouse from under the slate - the mouse is as big as the shrew and the slate is much heavier.
Here's the video.
Water shrews (Neomys fodiens) live near water (as you would expect) although dispersing youngsters can be found away from water, and I have seen one here before. Their normal diet is freshwater shrimps, caddis fly larvae, that sort of thing, and they will take beetles, worms, millipedes, etc. One of my previous posts documented a water shrew caching food, something I think hadn't been observed before. I have found a 2002 report of water shrews taking carrion but I don't think it has ever been filmed in the wild before.
I have a new waterside trail camera position, taking advantage of a newly fallen branch, the only drawback being that I now need waders to reach the camera. Having cameras watching the water's edge occasionally throws up a real surprise, as with this one. I haven't had good video of a heron before, mainly because they are so close to the cameras that they don't fit in the frame.
There has been a lot of water shrew activity here in the past few weeks and a heron caught one last week. This time the new camera position gave a much better view. Notice a second shrew on the bank to the right which sensibly beat a hasty retreat when it saw what had happened.
This was a new target for the trail camera, one I came across by accident. I was recording an otter hunting for frogs and the camera repeatedly had what appeared at first to be false triggers. When I looked closely there was a tiny water shrew swimming through the edge of the picture. I found where the burrow / nest was and set up another camera with a close-focus lens to watch the shrew. There were lots of fascinating recordings including this one of the water shrew eating its prey in its larder. Food-caching behaviour in water shrews was known about but this video may be the first time it was recorded. Ever. Anywhere. Amazing.
The water shrew appears on the trail camera every day, often just a glimpse as it dashes to and fro.
This short clip shows how frenetic its life is.
The recent lack of rain means there is no water flow so there is a film on the water and the shrew ends up looking a bit scruffy. It has no difficulty in finding things to eat right at the water's edge. At the end of the next video the shrew has caught a spider and seems to be biting it without eating it - perhaps to disable it with a venomous bite to save it for later.
The last video shows a visit from a cousin - a common shrew (Sorex araneus). It has a good look round but, unlike the recent wood mouse, it does not appear to steal from the larder, perhaps because there was nothing left. The video gives the opportunity to compare the two shrews. The common shrew is smaller and slimmer with pointier nose and a proportionately shorter tail. In infrared light it just looks paler but in daylight it would have tri-colour brown/cream colouration compared with the water shrew's black and white. Notice a water scorpion (Nepa cinerea) in the water as the shrew passes. It was lucky this was a common shrew and not the water shrew.
The water shrew's whole world is a bit of muddy bank under the culvert and a few metres in either direction. It is amazing to see how much it can find to eat very close by. The shrew seems to favour one spot under the culvert to eat (back left as we look at it). Sometimes it stays to eat (often with its back to the camera) but sometimes it seems to drop the food and leave to find more almost immediately. I came to the conclusion that it must be caching food there if it has a short-term surplus, and it doesn't seem to have any difficulty finding food. Then I found a paper from Austria* which describes food caches in the Eurasian water shrew, mainly consisting of caddis fly larvae and water snails. I presume the venomous bite of the water shrew will disable the prey to stop it escaping. Here is the shrew eating, first a shrimp it has just brought in, and then what looks like a larva, perhaps caddis fly, from the larder.
This water shrew first came to notice when the camera was set to record otters. Now several other things have turned up while the camera is after the water shrew. The most intriguing has been a wood mouse. Several times the camera has seen a wood mouse come to the cache and take food, either eating it on the spot or taking it away. As far as I can see it is always a caddis fly larva still in its case. The next video shows the shrew depositing food without eating it, then once coming from the nest/burrow for a snack, and then the mouse - twice it comes to take a caddis fly away and the third time it stays to eat it. I have added a short slow-motion replay to show the mouse biting the end off the casing and pulling out the larva, just like the shrew does.
The camera is still in place in the hope that it will record even more interesting behaviour.
* Haberl W. Food storage, prey remains and notes on occasional vertebrates in the diet of the Eurasian water shrew, Neomys fodiens. Folia Zool. 51(2):93-102 (2002).
A new target for the trail camera and this one is tricky! It started when I noticed a series of apparent false triggers on one of the otter cameras. When I looked closely there was a tiny water shrew in the corner of the video.
Looking through the otter-less clips I found several with the tiny shrew swimming upstream at amazing speed as it returned from hunting forays in the pool below the culvert. This is a montage of five episodes, the first two in a hailstorm.
Since then I have repositioned the camera a few times to get closer and better pictures. This was the first attempt.
Then I removed the scrap of wood and the root to get a closer view.
Here is the shrew with prey, first a freshwater shrimp and then a caddis fly larva. For the second one I have added a zoomed in view at 1/10 speed so we get a better view of the action.
Water shrews are mainly active at night, hunting underwater in complete darkness. Like other shrews they have to eat very frequently so they are sometimes seen in daylight. Paradoxically the camera found it more difficult to see the shrew in the day because of the high contrast between sunlit water and deep shadow under the bank. Here is a little montage of daytime action. This gives the best view of what I presume is soil excavated from a nest chamber in the bank, where the shrew disappears to at the end.
The water shrew (Neomys fodiens) is the largest of our three native shrews but is still small, slightly smaller than a wood mouse. As you can see above it is an excellent swimmer and hunts for aquatic insect larvae, crustaceans and small fish under water. It is very buoyant and pops to the surface as soon as it stops swimming. It has a dense waterproof coat and hairy feet and toes which help it to swim. Its nest is in a bank close to water with multiple entrances, some at or below the waterline and others higher to protect against flooding. I found two small holes 30-50cm higher up the bank above where these videos were recorded.
You can read a fascinating paper investigating the sensory abilities of the closely related northern water shrew (Sorex palustris), including how it can smell underwater, here.
A few years ago I saw a water shrew in my garden on a trail camera. Despite the video evidence I couldn't convince people what it was until I caught it in a Longworth trap and took photos to prove the ID - then they believed me! Water shrews are occasionally found away from water, perhaps as they disperse from one site to another.
This one needs to be careful for there is another predatory aquatic mammal about, one 500 times heavier* and for whom the shrew would be just a mouthful.
* Tyrannosaurus rex weighed over 5,000 kg, so 500 times larger than an otter. You can watch a brief David Attenborough video here, in which he talks about the water shrew and how it is probably similar to the earliest mammals that took advantage of the dinosaurs' extinction.
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.
I am going to post a bit more frequently for a while, partly for the benefit of folks like my mum and friends who are in isolation and can't get out and about. The restriction on activities will severely limit my excursions so most posts will probably be of happenings in the garden. For the time being, however I have a few other things I can share. This is a brief video I recently put on the Mammal Society Facebook page where it attracted more interest than my otter posts. I suppose that is because water shrews are sighted more rarely than otters. This one was dashing through the culvert where I film the dog otter.
This was the most surprising capture on a trail camera so far. I have been monitoring the comings and goings in the stone pile in the garden and had already seen common shrew, bank vole and wood mouse. Then this little beast made an appearance.
It is obviously a shrew but very different in appearance from the common shrew I had seen before. It is dark with white ear tufts, white spots behind the eyes and whitish feet. I was fairly sure it was a water shrew but I couldn't convince anyone I showed the video to.
So I decided to try to catch it. I set a Longworth trap and on the first day I caught two bank voles and a wood mouse (more on this another time). On the second day I had only a short time before going away for a few days but when I went to collect the trap there was something in it. And when I opened the trap there was my shrew. It is almost black with white underneath, white ear tufts and small white spots behind the eyes. It has white hairy feet and is very much a water shrew (Neomys fodiens). I put it in a plastic bag to weigh it and try to measure it and photograph it but it immediately tried to bite its way out.
So I put it in a large glass jug, the only thing I could find immediately that would keep it safe. The shrew ran round and round for a while but soon settled down when it realised it couldn't escape. It wasn't the easiest thing to photograph it in, or the easiest subject, but here are a few photos.
And a short video.
Then I put it back at the entrance to the stone. The shrew gave me a cold hard stare before it turned and disappeared, perhaps hoping to remind me that it has a venomous bite and will get me next time! I don't plan to catch the shrew again but I shall keep an eye on it with the trail camera. When I checked again yesterday it was still there but looking a bit more hesitant, perhaps fearing another trap. It is interesting that although it is a carnivore it takes sunflower seeds, even though casters (blowfly pupae) are on offer.
This was an extraordinary find in a pile of stones in dry woodland about 300-400m from the nearest watercourse. However, the Mammal Society website says "Occasionally they are found far from water in rough grasslands, scrub, woodlands and hedgerows, usually as young are dispersing". This one weighed 13g which is towards the lower end of the weight range and is probably young. I couldn't get accurate measurements but judging from the ruler on the photos its body length is probably about 65mm and its tail about 45mm which also puts it towards the lower end of the range for water shrews. The Mammal Society website says that mammals are some of the most under recorded species in Britain, perhaps surprising considering some of them are fairly obvious. I expect, however, that mammal observers are fewer than bird and insect observers. So I submitted my record, which turns out to be only the second one for Northumberland on their system (the red dot being mine).
The Mammal Society carried out a National Water Shrew Survey in 2004-2005 and you can read the report here. About one third of my garden is left as a completely wild wood (only ⅓ acre) for anything that wants to live there. Other things I have seen in the past, but not photographed, include weasel, stoat, woodcock and field vole.I don't know what else is lurking in there but I'll be using the trail cameras a lot more to try to find out.
