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————- Please note, this post contains some images and descriptions of dead animals that may upset ————-
I have done quite a lot of small mammal trapping over the past 5 years or so, starting as voluntary work but leading to full time employment as a professional in the field. For the majority of this trapping, I used Longworth traps. To me, Longworths are the standard, the baseline to which all others are compared. This may be partly because I learnt using them and humans are creatures of habit, but it is also a carefully considered opinion. And an opinion which was strongly reinforced during a recent 3 month project using Ugglan traps.
I outlined some of the advantages and disadvantages of Ugglan traps in this video, but didn’t directly compare them to Longworths – so here goes:
I find Longworths have quite a sturdy construction; made of plate metal with a nest compartment and entrance tunnel, which fits neatly inside the nest compartment for storage or transport (n.b. always store with the tunnel flap end facing down, so roaming creatures can’t get trapped inside).
Ugglans on the other hand, are mostly fashioned from metal mesh, which can get bent and broken worryingly easily. It also leaves sharp spikes at the edge of any sheet which makes cleaning the trap, or reaching in to try and extract stubborn captures, tricky and actually dangerous. You don’t want to be getting cuts while rubbing your hand against surfaces covered in rodent faeces and urine.
Ugglans also have a plastic bottom which on older designs slides out, making cleaning much easier and even proving useful for dislodging the clever individuals that stow away in the tight corners by the treadle plate. I got my hands on the newest design of Ugglan traps towards the end of the project, to replace a few that had been stolen/lost, and to my surprise it appeared that the plastic bottom could no longer slide out, although I didn’t have time to investigate properly.
Unlike the Longworth which is just a standard, the Ugglan comes in a variety of designs. Some quite useful as they accommodate animals of different sizes, but they also do traps with no or half covers. While some countries may have a climate that minimises the need for a cover, it still leaves the issue of less protection from predators or accidental stomping on (by cows, bison, antelope etc). The full cover, as shown in my photos, theoretically keeps the rain out and helps to keep the smells in, which attract predators on the hunt for an easy meal – I had one site in particular where lines of traps had been pawed onto their sides or the cover nuzzled up slightly, probably by a fox or badger. Luckily (for the potential captures), this site was distinctly lacking in mammals so only one mouse had the ordeal of being sniffed at in the night.
The biggest problem with these covers is that they simply don’t offer good protection from the elements. They don’t form a perfect seal even when new, and get bent and warped after a few uses, meaning rain and condensation get in. It’s only a few mm from the ground to the bedding so that easily gets wet, and wet bedding is how you end up with droves of dead or dying captures. The slide out plastic bottom does itself have some seals which aren’t perfect, so if the ground gets wet enough, water can seep in that way. The Longworth, being made from sheet metal and being fully enclosed apart from the entrances, is inherently more weather proof. So long as you angle the one open side down, you can be fairly certain that your fuzzy friends will stay dry and warm.
The nest box part of the Longworth also makes better use of space, allowing you to put more bedding and food in, and making it easier to extract captures. The Ugglan on the other hand, has a small nesting area with two pokey little spaces either side of the entrance mechanism ( which are only good for harbouring reluctant captures), and mesh sides which small mammals are experts at holding on to.
The standard way to empty small mammal traps is to pop the trap into a large clear polythene bag. With the Longworth, you generally put the whole thing in then break it apart (into entrance tunnel and nest box) with one hand, before checking to see if anyone is in the tunnel, then removing the tunnel from the bag if not. This leaves you with the nice short nest box which you tease the bedding out of gently until everything (including the capture) is in the bottom of the bag. Then you whip the trap out and you’re ready to process. Even this is more difficult with Ugglans, as they are longer and do not come apart. You put the trap into the bag, then have to reach all the way to the far end to open the hinged door, while holding the trap and bag with one hand. I found, when using anything but the largest bags, that sometimes the hinged door would just be pushed shut again by the bottom of the polythene bag. Since the animal very rarely just decided to pop out of the open end of its own accord, and you couldn’t possible put your hand in the far end to encourage it out, this didn’t end up mattering that much. I almost always pulled the plastic floor out instead, as it created a much larger hole for the animal to fall out of, and could be pulled from the end near the top of the bag. This may create a problem if the newer models are designed with floors that don’t pull out.
One of the main selling points of Ugglans (apart from their lower price) is that they are multiple catch traps. Once a Longworth has sprung, the door closes and no one else can get inside – particularly annoying if it’s accidentally or prematurely sprung with nothing inside. In Ugglans, you commonly get 2 or even 3 captures. This is great in that it simplifies some of the statistics as you don’t have to account for trap saturation, but it creates other complications too. One issue is that animals can more easily escape. If wood mice turn back quickly, their tails can still be caught in the flap, keeping it open enough for a mouse to nuzzle its way out. Even if the flap has completely closed, most traps (after a seasons use at least) don’t have a tight seal so big captures can pull it open again if they happen to get their paws in the right place. Captures that are already in can leave when a second individual weighs the flap down and thinks about entering. This, as well as multiple captures generally, means you have to put silly amounts of food in, lest one greedy mouse eat it all in the early evening then escape as a little vole enters, who then has no food and dies overnight. Or worse still, if multiple captures are inside with not enough food, they can turn to cannibalism. I am sad to say I saw this quite a few times during my recent project. While I know some small mammals trapped in a small space together may just fight for a variety of reasons, these were very definite cases of one animal eating the other. It got to the point where I was putting equal amounts of food and bedding in the traps at one site with a large mouse population, but I still had some deaths.
Once made, Ugglan traps cannot really be adjusted for different weights/species, as the metal counter weight is welded in place. Albeit a little fiddly, Longworths can be adjusted by using a small screwdriver to change the spring tension and /or a ramp in front of the treadle. The small spring and other fiddling bits of metal work can be damaged but I have been told it’s not that hard to get hold of replacement parts. Both traps can have a shrew hole drilled in the plate metal. This is basically a hole big enough to let pygmy and common shrews out, but small enough that mice can’t get out. Obviously very small mice/voles can get out, and very big shrews may be stuck but having a shrew hole in the traps is normally enough to avoid the need for a shrew licence, and allows you to not include a protein source in the bait. Here’s a picture of the mother of all common shrews (and possibly an actual mother-to-be judging by her size), who ended up in one of my traps and was far too big to squeeze out of the shrew hole. Thankfully, she was still outwardly in fine fettle when I checked the trap, and hopped off happily once released. I had a volunteer with me that day and had just finished explaining that we’d only see mice or voles, so it was quite a shock to us both!
Shrew holes in any make of trap are somewhat of a controversial topic, as animals too large to get out sometimes try so hard to squeeze through, that they hurt themselves. This is most often mice, as they are large and more energetic/curious, but voles or large shrews can be hurt too. I believe some research is ongoing into this subject to try and ascertain just how large of a problem it is. Early on in my recent project, I caught a large female wood mouse who had a slight scuff on her snout. I thought little of it until I went to put the now empty trap in my bag and saw a circle of blood around the shrew hole. Luckily, this mouse had been so large that she didn’t even have a chance at squeezing through, so had just pushed her nose in and received a small cut. She must have kept trying though, to get blood all around the hole.
I hate to see any suffering in animals so this was an unpleasant site, but my spirits were boosted slightly when I caught her again a few days later, seemingly fit and well. Some months after this, in the very final week of my role, I was trapping in a nature reserve. My specific location was a good 25 minute walk from the road. On the second day, I bent down to lift up the cover of a trap (the quickest way to tell if you have any captures), to find the soggy head of a little mouse poking out of the shrew hole. It was alive but subdued, and had probably been there some time. I tried everything I could to get that mouse out, searching through my bag for any kind of lubricant but I simply couldn’t free it. I am a practical sort and knew that deaths are an inevitable part of trapping but on that day I just couldn’t bring myself to hit the end of the trap against a tree (the only way I could kill it as there were no boulders around). I ended up taking the trap to the parks office, and a ranger squeezed the mouse out for me, but as expected, the pressure of being squeezed back through was too much and the mouse starting fitting and died shortly after.
For that reason, my preference will always be to use traps without shrew holes, and to provide a large amount of protein rich bait instead. Shrews are known to be very territorial and aggressive, so if more than one end up in the same trap, there is likely to be serious fighting.
From a research point of view, the fact that the plastic bottom and metal cover of Ugglan traps comes off means it is hard to make them individually identifiable. Which section do you write on? And if it’s not all three, then how do you make sure you’re putting the right parts together? This may not matter for casual users but for accurate scientific research it could be vital. Their mesh and removable part construction makes the actual setting hard too. If you are using grain and put it in before the traps are in place, moving them around even slightly results in grain falling out through the mesh or ending up in the entrance section. The same is true for using sawdust as bedding (although I recommend against using sawdust at all). Because the separation between the entrance and nest section of Ugglans is mesh, food and bedding can very easily be pushed between the two. Whether they do this on purpose for unknown reasons, or accidentally with their back legs when trying to get out of the shrew hole, I saw this quite a lot. And if more than about half of the bedding had been pushed out, the animal tended to be in a bad way or dead, from the cold.
As mentioned earlier, I have found the easiest way to check Ugglans is to bend down and lift up the metal cover. By contrast, you can normally tell if Longworths have definitely not been sprung from a distance by looking to see if the door is open or shut. It’s a small thing but I much prefer not having to bend or crouch down (generally with a big bag on too) every few metres.
(n.b. This post was originally envisaged as a video, but I haven’t had a chance to borrow a Longworth trap, and without one to demonstrate on, a video didn’t add much over a blog post)