RNR small mammal surveys

RODDEN NATURE RESERVE, FROME, SOMERSET,UK

Small mammal surveys Aim: complete (geographical) survey of small mammal population using Longworth traps to record biodiversity, frequency, habitat, season and temperature trends.

2009 12 Longworth traps purchased. First 6 with shrew holes, second six without. First rounds of trapping yielded common shrew, wood mouse, bank vole, field vole. Traps set overnight, in warm damp weather, baited with mixed seed and casters.

2010 Working via a methodical pattern (see map)

Round 1 April 2010 began at westernmost reach of reserve and proceeded eastward by lakeside as illustrated. Early sessions included daytime settings as well as night time but these were ceased as they yielded no results. The 12 traps were baited with mixed seed and mealworms.

Survey a (weather: dry. temp low 2ºC) Riverside, trees bushes, open field. 8.4.10

location	contents
riverside	wood mouse
fallen branch by path	bank vole
open field, grass	empty
riverside, scrub	bank vole
riverside, scrub	wood mouse
riverside, scrub	bank vole
open field, brambles	empty
open field, grass	empty
riverbank (higher), scrub	wood mouse
riverbank, fallen log	bank vole
riverbank, fallen log	wood mouse
riverbank, grass	empty

Survey b (weather:dry . temp low 5ºC) Riverside, grassland and waterlogged ground under trees. 9.4.10

location	contents
open grass	empty
open grass	empty
open grass	empty
open grass	empty
Riverside, under tree	wood mouse
waterlogged ground by fallen tree	wood mouse
grassland, under tree	bank vole
waterlogged ground, base of tree	wood mouse
Riverside, base of tree	wood mouse
Riverside	empty
Riverside, in scrub	wood mouse
Riverbank	empty

Survey c (weather:dry . temp low 7ºC) Field, hedgerow, scrub by bird feeders. 10.4.10

location	contents
grassland, under tree	wood mouse
Hedgerow	wood mouse
Hedgerow	empty
Hedgerow	wood mouse
Hedgerow	wood mouse
scrub by bird feeder	wood mouse
bare earth by bird feeder	empty
Hedgerow	empty
Hedgerow (nr river)	empty
Riverbank, base of tree	empty
scrub by stream	field vole
scrub by tin	empty

Survey d (weather:dry . temp low 6ºC) western lakeside, up to path. 12.4.10

location	contents
Lakeside, close to water	wood mouse
Lakeside, nearer to path	empty
Lakeside, close to water	wood mouse
Lakeside, nearer to path	wood mouse
Lakeside, nearer to path	wood mouse
Lakeside, close to water	empty
Lakeside, nearer to path	empty
Lakeside, close to water	empty
Lakeside, nearer to path	empty
Lakeside, close to water	empty
Lakeside, close to water	empty
Lakeside, close to water	empty

Survey e (weather:dry . temp low 4ºC) Southern lakeside to road end. 13.4.10

location	contents
Lakeside, nearer to path	empty
Lakeside, close to water	empty
Lakeside, nearer to path	empty
Lakeside, close to water	wood mouse
Lakeside, nearer to path	empty
Lakeside, close to water	empty
Lakeside, nearer to path	empty
Lakeside, close to water	wood mouse
Lakeside, nearer to path	empty
Lakeside, close to water	empty
Lakeside, nearer to path	empty
Lakeside, close to water	wood mouse

Observations from round 1

Against a backdrop of typical randomness in what is caught, variables that might affect what was yielded in these 60 trappings include location (microhabitat) existing population sizes, different behaviour/foraging patterns, weather conditions, especially temperature and season (availability of food).

All species covered are noted as being typically nocturnal. Open field areas yield less. Proximity to wooded areas and water yielded more. Wood mice predominate. Bank voles appear to favour the more covered and wooded areas.

As the round proceeded temperatures generaly dropped and habitat became less wooded and more characterised by the lake and its vegetation. It also progressed into areas of greater human footfall, otter and waterfowl presence.

Round 1 (continued)

Survey f (weather damp. temp low 6 ºC) Western end of large plantation south of western pool on north facing slope) 8.5.10

location	contents
dense plantation of young trees	empty
dense plantation of young trees	empty
dense plantation of young trees	empty
dense plantation of young trees	wood mouse
dense plantation of young trees	empty
dense plantation of young trees	empty
dense plantation of young trees	empty
dense plantation of young trees	wood mouse
dense plantation of young trees	empty
dense plantation of young trees	empty
dense plantation of young trees	empty
dense plantation of young trees	empty

Despite a somewhat thin yield on the traps, possibly due to dapril mp weather, inspection of the corrugated iron 'tins' and felt squares on the southern edge of the plantation gave two common shrews. First of this survey but caught on site in previous trappings. A water shrew was seen by Mick Ridgard in late April.