Survey information
The biggest problem with conserving the water shrew is the lack of existing information about its distribution, population status and habitat preferences. We need more data so that accurate recommendations can be based on firm evidence.

There are several simple methods to conduct water shrew surveys and they can be carried out at any time of the year (though they are most successful in the summer and autumn). They are as follows:

Refugia without bait
Sheets of corrugated iron or bitumen roofing felt (ideally 0.5m x 1.5m) can be placed near riverbanks and stream edges. The warm, sheltered conditions generated by the sheets attract inquisitive small mammals who then enter underneath. Once the refugia has been left in a partially shaded place for 2 weeks (so the grass has died back) the sheeting can be lifted to expose any creatures present. Its generally best to conduct the survey in twos so that one person can lift the refugia while the other observes the rapidly escaping occupants! The sheets can be inspected several times during the summer/autumn but its worth noting that the warm conditions under the sheets may also attract reptiles, including adders, so beware!

Refugia with bait
The procedure is essentially the same as above but includes sliding a white plastic lid or sheet with a handful of blowfly pupae, under each refugium. The water shrews can then eat the bait and, hopefully, will produce scats (which will be clearly visible against the white of the plastic). The scats must be recovered from the refugia, dried in fresh air and stored in paper envelopes.

The faeces can then be analysed for remains of aquatic prey (a sure sign of water shrews). Any scat samples sent to us at SWT for analysis will be gratefully received, or if you like you can analyse the scats yourself.

Bait tubes
Bait tubes are simply lengths of white plastic tubing (approximately 4cm in diameter and 20cm long) with bait stored inside. The basic principle is like that of refugia with bait however one end of the pipe is covered with muslin or nylon netting (secured in place with a rubber band). The bait is placed towards the covered end of the tube and the open end should be flush with the ground to allow small mammals to go in easily. Bait tubes should be laid flat amongst the bank vegetation using small wire hoops pushed in the ground. The piping can then be retrieved (after 2 weeks) and the scats analysed.

Whichever method is used, it is important to mark on a map where the refugia or bait tubes were placed and the type of vegetation it was located in (woodlands, grassland, scrub). Additional notes on: the speed of the water flow (fast, slow, static): the substrate type (rocks, gravel, mud): the adjacent land use (pasture, arable, woodland, fen): and the management would all be invaluable in helping us to understand the needs of water shrew.