IT’S Britain’s smallest mammal and there’s a growing threat to its existence.
So each year a group of nature lovers gather at Beighton Marsh to take part in the harvest mouse survey conducted by Sheffield Environmental Planning, Sorby Natural History Society and Sheffield Landscape Trust.
The group is led by expert Derek Whitely, who says that in years gone by harvest mice would build their nests in corn.
But modern farming methods are to blame for removing their habitat and numbers have plunged significantly.
The harvest mouse is now considered to be a threatened species, now found in wet areas where they make their nests from coarse grass.
Group member Peter Wolstenholme said: “They build their nests in spring by slitting living phalaris leaves and weaving a tennis ball sized nest in which they raise their brood before deserting the nests for winter quarters.
“The easiest way to survey a colony is to find and count the redundant nests each year in November, compare numbers, and build a pattern over the years thus establishing the general rise or fall of numbers.”