Britain’s Smallest Mouse Found at Denmark Farm

Here at Denmark Farm we regularly host a number of ecology and conservation courses, led by tutors from the School of Education and Lifelong Learning at Aberystwyth University. Our 40 acre nature reserve provides an ideal study site, and the wildlife records from these courses are a valuable addition to our species monitoring programme. However, one record from a recent mammal course caused a little more excitement than usual: a harvest mouse!

Harvest Mouse (Britain's smallest mouse)

(photo: The Mammal Society)

As far as we know, this is a ‘first’ for Denmark Farm and one of only a handful of records from Ceredigion. In fact, there were only 30 harvest mouse records for the whole of Wales between 2000 and 2011. The harvest mouse is our smallest rodent, weighing less than 10 g. Its Latin name (Micromys minutis) literally translates as ‘miniature tiny mouse’!

One of the reasons that it is rarely recorded, is that the animal itself is very difficult to spot. However, they do leave signs. Not droppings or footprints which other mammals helpfully leave behind, but nests which the harvest mice weave into long vegetation.

Example of Harvest mouse nest (2)

Harvest mouse nest

These are about the size of a tennis ball, although smaller non-breeding nests can also be found. This is what the course students found, under the expert eye of tutor Penny Lewns.

Recent research indicates that these little rodents are disappearing from many parts of their former range, so we were really pleased to discover that they are here.
The mammal course students also found water shrew and yellow-necked mouse, the latter another ‘first’ for Denmark Farm, and both species very much under-recorded in Ceredigion . The yellow-necked mouse is similar to a wood mouse, but has a yellow unbroken collar underneath the chin, and tends to be bigger and feistier.

yellow-necked mouse (when compared to other mouse species) jpeg_0 (2)(photo: The Mammal Society)

These recent records are a great addition to our mammal list, which includes polecat, fox, badger, several species of bats, bank and field vole and even occasional sightings of otter. We have also found signs of dormice, although not yet lucky enough to find one in the nest boxes we have installed around the site.

However, our Dormouse Day on Saturday 19th Sept (from 10am) might give us the opportunity to find one of these elusive mammals when we check our dormouse boxes. There will be a chance for volunteers to learn a little more about the ecology of this arboreal (tree-dwelling) species, and we may also be lucky enough to find a yellow-necked or wood mouse in the boxes. All welcome, bring waterproofs and a packed lunch.

And if you see a harvest mouse or nest or any other small mammal in your own local ‘patch’, please do report your sighting to your Local Records Centre (LRC).