I was wondering about how to do a small mammal survey on the reserve, the last having been carried out in 1994. I want to get a good idea of what species we have, and the usual way to do this would be with small live traps called Longworth Traps, which are tried and tested and have been used in small mammal survey for nearly 70 years!
These traps are expensive and time-consuming, as they need to be checked ever 12 hours (or less), and once it’s been triggered it won’t register anything else until you’ve been along to have a look, released the catch and reset it.
So I thought about how I could use one of our Trailcams, a motion-activated camera with an infra-red flash and lens (for taking pictures at night) and found a paper called A novel method for camera-trapping small mammals. In it, they use a large plastic barrel with the base cut out, and a camera pointing down into it. The base is replaced with a gridded floor, and baited, so that small mammals entering are seen from above and measurements for size can be seen:
Additionally, as they want to use it in a tidal area, they affix it to a large float, and then so long as it is baited, it can be left alone.
I thought that sounds like it might be quite interesting! First I’ll need a large plastic bucket with the base cut out… Luckily, the sea provides us with plenty of rubbish, including a large plastic bucket with the base cut out. How convenient.
I fixed some L-shaped brackets, to hold an off-cut of corrugated plastic sheeting in place, then cut a hole in that for the camera to sit, so the whole thing looks like this:
Not very hi-tec! I drilled a few small entrance holes, put it out in the yard and baited it, along with the second camera trap pointed at it to see if anything shows interest but doesn’t go inside.
I’ll have a check of it after a few days. I’ve just put it in the yard here rather than out on the reserve already because I believe as it is, it won’t focus on something as near, and the infra-red flash will be far too bright! They’re designed to take pictures up to about 14m away. But it would be good to get a feel for how it works to start off with.