We had a fantastic surprise at the start of this week, as our reserve team stumbled across something very special indeed – two harvest mouse nests! Harvest mice are the smallest mammals in Britain, weighing around the same amount as a two pence piece! Although they are found across Europe, it’s fantastic to see their nests here at Fairburn because this reserve is at the northern limit of their range here in the UK – they aren’t found further up than Yorkshire.
These tiny little mice can be identified by their pale brownish ginger fur and white belly. They also have tails as long as their bodies, which they use for gripping whilst climbing through long vegetation, which we have plenty of here on the reserve.
Harvest mice were thought to be extinct in Yorkshire from the 1930s, but evidence of them has been seen at Fairburn Ings and the surrounding area over the past few decades, as the Aire valley has been a bit of a stronghold for them. Nationally however, they are becoming scarcer due to habitat loss, which makes our population here at Fairburn even more important.
Harvest mice are clever builders – their breeding nests are built out of woven grass around 10cm in diameter, and constructed a few feet above the ground. Non-breeding nests, which are used for the rest of the year are about half the size, and will be closer to the ground or even in buildings. Given that we had seven floods on the reserve last year, it’s pretty incredible that they seem to be doing so well!
Come along to the reserve and see if you can spot any signs of these fantastic little mice!