On a cool morning in October, our first-year ecology and conservation cohort ventured out to check the small mammal traps that had been set up the previous day. We found that 9 of the traps were now occupied by wood mice.
We used Longworth traps containing peanut butter as bait as well as hay, blowfly larvae, and fruit, to ensure any small mammals caught would have enough food.
The traps are made up of a nest box and a tunnel, which are latched together. The tunnel has a trap door that is triggered by a treadle at its opposite end. This traps the small mammal inside the tunnel and nest box. Longworth traps are a type of live animal trap and are considered a more humane method than the lethal traps which were more commonly used by scientists in the past.
The nest boxes with the mouse inside were put into plastic bags, and then the boxes were removed, leaving a mouse in the bag. This allowed us to measure and weigh them. We also identified the sex of each mouse, opening the bag every few minutes to make sure that they had enough air. They were then released back into the wild.
After releasing the mice, we set up the Longworth traps again, ensuring that there was enough food and bait in each of them and that the tunnels were securely latched into the nest boxes. Finally, we placed the traps out along the edges of the exposed, grassy area, to allow small mammals to find them from the shelter of the bushes.
Profile of the Wood Mouse
(Apodemus sylvaticus)
The wood mouse (also known as field mouse) is one of the most common small mammals in British woodlands. They tend to be cautious in order to avoid predators. Being mostly nocturnal animals and living in underground burrows, wood mice can be difficult to spot.
Habitat
True to their name, wood mice live in woodland habitats, as well as grasslands, farms, and gardens.
Identification
The wood mouse has a body of around eight to ten centimetres long with a seven to ten centimetre-long tail (a similar length to its body) and weighs about 13-27 grams. These rodents have brown fur with lighter-coloured fur on their undersides. They have prominent eyes and large ears. Wood mice can be distinguished from their less common lookalikes, the yellow-necked mouse, by the absence of a band of yellow fur around their upper chest.
Ecological interactions
The wood mouse is omnivorous, eating foods such as fruits, nuts, insects, earthworms, and centipedes. They are also the prey of larger mammals and birds of prey, including weasels, stoats, cats, foxes, owls, and kestrels. They are such an important food for tawny owls that decreased wood mouse populations may lead to reduced breeding of the owls.
