Harvest mouse survey training, looking for nests

Is the countryside still heaving with harvest mice? You know the type – the cute ones from children’s picture books, usually seen curling a tail around an ear of corn with poppies in the background. Well, it’s not like it used to be that’s for sure. In the old days apparently sheaves of corn could shake with mice when taken in. But modern farming isn’t so mouse friendly. So how widespread are these tiny charismatic mice now?

Conservationists want to know, and here in Devon the Devon Harvest Mouse Project is training volunteers to survey grassland in winter for the previous summer’s abandoned nests. Other counties are running similar schemes. Maggie went on a training day this weekend at Beer Mill Farm, near Holsworthy (many thanks for hosting it, Elaine and Richard).



Pete Cooper, the project officer, told us how the scheme works. At this stage, volunteers are just looking for ‘presence/absence’ information, trying to search at least one site in each 10km square. A second phase may look at actually estimating population sizes. That’s more difficult, as the mice are hard to spot, and one nest doesn’t necessarily mean one mouse family – the female may build several breeding nests over the summer, and the males will build bachelor pads too.

So where are they now? Not hibernating apparently. They are more likely to be dispersing through the environment (encouragingly, they can turn up in new suitable sites fairly soon after these are created).

But they do need a certain type of grassland habitat. They like long grass stems, because they weave the nest among living stems, incorporating them in the structure. For the same reason, they don’t like material that is too course (like rushes), though apparently harvest mice are found in reedbeds sometimes. Cooksfoot grasses (which we leave tussocky patches of in the lodge field), and also purple moor grass (which we have on Popehouse Moor Site of Special Scientific Interest) are also well liked.

We’ve seen plenty of harvest mice nest there in the past, and recently found what we think is a nest outside Otter Cottage. So we’ll keep an eye out over the next month while there’s still time for winter surveying.

A lot of fuss about mice?

But they are so super cute! They are a lovely reddish brown, are amazing acrobats, and weigh only about as much as a tuppence. They are also closely associated with our agricultural history – they’ve been with us since Neolithic times apparently. But if you just don’t like mice full stop, think of them as essential snacks for other creatures – like owls.