Genre: Information/Explanation

The Harvest Mouse in Cheshire - 1999-2000 Survey Introduction : Harvest Mice ( Micromys minutus Pallas ) , are currently the subject of much debate in Cheshire . Chester Zoo is initiating a breeding programme with a view to re-enforcing populations in the county . Harvest mice weave nests in monocotyledonous herbs that are difficult to find as they are woven from living grass , but become more visible in early winter as the grasses die off ( Harris & Trout 1991 ) . Suitable areas of habitat include cereal fields , rough grassland , reedbed and fen , and the Harvest Mouse can be the most abundant small mammal in wetland ( Perrow & Jowitt 1995 ) . In Britain it is most common in the South and East , but its distribution in North West England is uncertain . The West Midlands and Lancashire yielded three and two records respectively during the Mammal Society survey of the 1970s , while Cheshire , sandwiched between these two regions , had 13 records . The Cheshire records were mostly from the fringes of metres ( Harris 1979 ) . Only one record for Cheshire was found during a re-survey of the 1970s sites , but five of the 13 original sites , including Rostherne Mere ( a National Nature Reserve ) , went unsurveyed . A record of a nest in Cock's Foot grass ( Dactylis glomerata ) growing inside a tree guard in a young plantation was the only other recent record , ( 1997 , Aston ) . To investigate this apparent paucity of records in the last 20 years , a survey of the land covered by the Cheshire Wildlife Trust ( Cheshire , the Wirral , Stockport , Tameside and Trafford ) was planned for 1999 and 2000 . Methods : Methods currently employed for surveying include nest searching and stalk-zone trapping ( used here ) , hair tubes and baited tubes . Nest searching can be quantified in various ways ; in this survey , suitable habitat was searched in 30-minute blocks , recording the number of nests found per search , and the species of grass in which the nest was woven . All historical sites with adequate map references were surveyed by nest searching ; two of the most recent sites were also surveyed by stalk zone trapping . Additional sites were chosen for survey through consultation with Phase 1 habitat maps , advice from colleagues at the Trust , and requests from landowners and rangers . Trapping was carried out on a small number of sites , as there were a number of limiting factors , including the time of year , access , and the proximity of public byways . Longworth traps were placed on platforms constructed from hardboard , plastic tubing and bamboo canes . These were then placed in a grid of 20 x 3 at 10 metre intervals in areas of long grassland or reed . Trap sessions at each site lasted four days , making a total of 240 trap nights per site . Results : Signs of harvest mice were found in 24 one-km squares in Cheshire . 53 nests were found at 25 sites out of 126 sites surveyed ( 19 . 8 % ) . Table 1 Monocotyledonous herbs utilized for nest building by Harvest Mice in this survey , compared with national results from Harris ( 1979 ) : Species : Cheshire : National : number of nests % ( Harris 1979 ) Alopecurus spp. 1 1.9 % 0.1 % Arrhenatherum elatius 8 15.1 % 2.8 % Carex spp. 6 11.8 % 2.6 % Dactylis glomerata 12 22.7 % 20.7 % Deschampsia cespitosa 4 7.5 % 2.1 % Elymus repens 2 3.8 % 6.6 % Juncus spp. 2 3.8 % 1.9 % Phalaris arundinacea 16 30.2 % 13.8 % Phleum pratense 1 1.9 % 0.7 % Phragmites australis 1 1.9 % 9.9 % Other 0 0 % 38.8 % Table 2 Habitats from which Harvest Mice or their nests were recorded , in this survey , compared with national results from Harris ( 1979 ) : Habitat : Cheshire : National : No. of Records % ( Harris 1979 ) Field Edge 1 1.9 % 9.9 % Fen 31 57.4 % 5.1 % Rank Grassland 8 14.8 % n / a Reedbed 4 7.4 % 8.6 % Roadside Verge 2 3.8 % 4.5 % Stream / Riverbank 5 9.3 % 6.3 % Young Plantation 3 5.6 % 3.1 % Other 0 0 % 62.5 % For ease of comparison , " Marsh " from Harris ( 1979 ) was taken as " Fen " here . There was no corresponding habitat for " Rank grassland " in that study . 53 ( 98 . 1 % ) of records were nests , while only one ( 1 . 9 % ) mouse was trapped . While this seems a low yield for trapping , the other sites that were trapped yielded no records from either trapping or nest searching . In this study , all records came from land under 500 feet , and no Harvest Mice were found east of Holmes Chapel . In the 1970s survey of Britain , 90.3 % of all records came from land under 500 feet ( Harris 1979 ) , as did all 100 % from the Sheffield area between 1980 and 1996 ( Whiteley 1996 ) . Discussion : The Harvest Mouse is still present , though local in the county , despite the paucity in records over the last 20 years . The most common habitat for the mice in the county is fen ( with 57.4 % of all records ) , which occurs around the fringes of meres , along the bank of rivers and canals ( such as the river Weaver navigation ) , and in wet meadows . In contrast , Harris ( 1979 ) found 57.7 % of nest records were from " dry habitats " . The meres support reedbeds that dry out into Phalaris - and Carex-dominated fen beds , all habitats that support Harvest Mice . The fact that dairy grazing puts dry grassland at a premium also supports the bias towards wetlands . The Countryside Stewardship Scheme may benefit the species , by creating harvest mouse-friendly habitats such as field margins and hedgerows . A warm dry summer in 1999 may have meant that there was a large population produced that year . The increase in records may simply reflect increased surveying ; as 126 sites were surveyed during this study , resulting in 25 records ( 19 . 8 % ) , compared to one record from eight areas ( 12 . 5 % ) of suitable habitat surveyed during the 1997 re-survey ( T. Newman pers comm ) . One negative record from 1997 , at Pickmere , proved positive in 2000 . References : Harris S. ( 1979 ) History , distribution , status and habitat requirements of the Harvest Mouse ( Micromys minutus ) in Britain . Mammal Review 9 : 159-171 . Harris S. & Trout R C. ( 1991 ) Harvest mouse Micromys minutus pp 233-239 In : The Handbook of British Mammals , Eds . G B Corbet & S Harris 3rd Edition . Blackwell Scientific Publications , Oxford . Perrow M & Jowitt A ( 1995 ) What future for the Harvest Mouse ? British Wildlife 6 : 356-365 . · Whiteley D. ( 1996 ) Harvest Mice in the Sheffield Area 1980-1996 . Sorby Record 32 : 37-41 . Acknowledgements : Robert Carthy and The Cheshire Wildlife Trust wishes to acknowledge the financial support of English Nature . Thanks to P. Morris and D. W. Yalden for use of photographs .