Small Mammal Activity

The Cambridgeshire Mammal Group joined forces with the CRT to undertake research and training activities related to the small mammals on the farm recently.

These are a crucial part of the biodiversity of the farmland, not only because they provide food for our iconic Barn Owls and other star species, but in their own right they are fascinating and attractive species, which we seldom get a chance to see. Some of them are rare and declining in the countryside and are of considerable conservation value, but because they hide under the grass and are mostly nocturnal, we rarely know how they are doing!

The best way to study the diversity of small mammals is to use traps, which catch the animals alive and provide them with a temporary home. We used the standard aluminium Longworth Traps, which have a nest box where food and bedding can be provided for the animal’s welfare until it is checked and released back into the habitat. The traps are set at dusk and checked first thing in the morning so that the animals are not kept in for too long.

The first activity was a new density estimation grid of Longworth traps set out in Nan’s Meadow. We set up a 50m x 50m grid, with a pair of traps at 10m intervals (a total of 36 paired traps). For this exercise, the traps were put in place with bait and bedding, but set such that the trap door would not close for the first two nights, so that animals got used to them as a safe place to find food. They were then operated as traps over two nights, checking each morning. Any mice or voles caught were marked with a small ‘haircut’ by clipping the fur, so that we could recognise any animals that came back to the traps twice. This system allows a statistical analysis to be performed which will tell us the density of animals in the meadow. The majority of animals caught were Wood Mice, but there were also several Short-tailed Field Voles and Bank Voles, one Common Shrew, and most excitingly, we caught 10 different Harvest Mice – a Biodiversity Action Plan species that is in decline on farmland because of the loss of meadows and rough areas such as we provide at Lark Rise Farm.

The second activity was a training course for young mammal enthusiasts. About 12 trainees attended, mainly students from Anglia Ruskin University and they were given theory and practice. The indoor information was carried out in our education centre, while 20 Longworth Traps were set around Birds Farm farmyard and campsite. The first couple of traps checked on Sunday morning held Wood Mice, which are super little lively animals, with big eyes and ears suiting their nocturnal activities and lovely long tails to help them climb trees and shrubs. Then the next two traps were disappointingly empty – everyone had set two traps and had to remember where they put them, so there was a personal stake in whether or not each trap had caught something! There was then another Wood Mouse followed by a Bank Vole – coming after 3 Wood Mice, this prompted one excited student to say “I love seeing different things!” which basically is why biodiversity conservation is so¬† important! Our traps around the farmyard mostly caught Wood Mice with one or two Bank and Field Voles, but at the end of the morning check session we got to the big hedge at the back of the campsite, and one of the traps here held another special species, the Yellow-necked Mouse. This is a rarer, larger and more lively cousin of the Wood Mouse, and a real performer.

Short-tailed Field VoleHarvest mouse_Nov 14Harvest mouse in bag_Nov 14


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