The Longworth trap

Now that we are all more or less confined to barracks it is a good opportunity for me to do a bit of trail camera work in the garden.  The northern part of my garden, about ⅓ of an acre, is a small copse of mature trees which is left wild for the benefit of whatever lives there.  Over the years I have built several log piles and brash piles, some of which are 25 years old and largely disintegrated.  They house many invertebrates and provide homes for birds and small mammals.

The Longworth trap, as you can't guess from its name, was designed and developed by two Oxford scientists named Chitty and Kempson in 1949.  Its design hasn't changed significantly since then and it remains the standard live-capture small mammal trap for study of mice, voles and shrews.  The nest box contains dry grass for bedding and bait - usually a mixture of sunflower seeds, apple, carrot and casters (blowfly pupae normally used for coarse fishing).  The casters are for shrews which can consume their own weight in food each day.  It is important to inspect the trap regularly to release the captive animal and to provide enough food until it is released.  The nest box is connected to a detachable tunnel containing a treadle which closes the door behind the animal when activated.  In the past I have caught bank voles, wood mice, common shrews, a pigmy shrew and a water shrew in the garden.

I mostly monitor the small mammals in the garden just with a trail camera but decided to combine it with a Longworth trap to show the latter in action.  When I use Longworth traps in the local nature reserve I usually set them without prebaiting as the capture rate is high.  However, the trap can be fixed open with a prebait catch to allow the animals to come and go and get used to it.  Here the prebait catch is set and you can see the bank vole is happy to sit in the tunnel while eating.

Wood mice, on the other hand don't eat in but prefer takeaways.  They like sunflower seeds best but will eat apple.

Banks voles are also rather choosy and prefer apple to carrot.

The first time I set the trap to video it the bank vole had pushed some diced carrot under the treadle which made it difficult to trigger, although it did work in the end.

Two days later I tried again.  The bank vole (probably the same one) was more wary but in the end it couldn't resist the smell of fresh apple.

I have put the trap away now and will use the trail camera to capture more videos of the animals in a more natural setting!