Page 26 - MISE Project Report

Searching for Britain’s Smallest Rodent Harvest Mouse
Searching for Britain’s Smallest Rodent
Article by: Harvest Mouse
Aline Denton Becky Clews-Roberts
With only 30 records between 2000 and 2013 (Cofnod report March 2013 Tapping, R; Harvest Mice in Wales – Where might they Be?), we knew that locating harvest mice in Wales would be tricky - they are, after all, the smallest rodent in Britain! However, MISE volunteers stepped up to the challenge and have made a concerted effort to help us find them. Indeed, more than 800 volunteer hours have been spent carrying out bait pot or nest search surveys and owl/ raptor pellet dissections between 2011 and 2014.
The harvest mouse is our smallest member of the rodent family at just 5-7cm long and weighing the same as a 20p coin. Its small, hairy ears distinguish it from all other British mice and its most outstanding feature is the prehensile tail used as a fifth limb to assist with climbing grass stems. A further unique adaptationthattheharvestmousehasisits ability to construct tightly woven nests within its preferred grassy habitat, leaving a useful sign for mammal surveyors.
MISE Project Officers were keen to train volunteers in order to equip them with the knowledge and skills required to undertake surveys using a range of techniques. Six survey training workshops were arranged between 2012-2014 where a presentation was given about harvest mouse ecology and
the theory behind the survey methods was discussed. These workshops were followed up with hands-on practical survey training to ensure participants could recognise suitable habitat and the field signs – distinguishing a vole nest from a harvest mouse nest has tested us on more than one occasion! Several of our volunteers felt confident enough following the training to undertake their own surveys and we hope that this will continue.
Raptor and owl pellet analysis workshops were also organised. This can be a useful, indirect method of detecting the presence of harvest mice in an area. Barn owl and kestrel pellets are easiest to collect in the field compared to other birds of prey since they have preferred roost locations
often known to local birdwatchers. Once the pellets are dissected and the remains sorted it is possible to identify harvest mice skulls from the number of root holes left after removing the molar teeth. In the case of harvest mice, 5-root holes become apparent, which is a unique feature of harvest mice. The presence of harvest mouse remains in a pellet gives an indication that they are present within the territory of that bird species.
Harvest mouse skull showing 5-root holes that become apparent once molar teeth are removed.
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