Water Shrews have returned to the Bourn Brook at Lark Rise Farm following an absence of seventeen years.
The findings were identified by CRT’s Head of Monitoring, Dr Vince Lea, a team of CRT monitors and the Cambridgeshire Mammal Group as they undertook a small mammal trapping survey in Nan’s Meadow on Lark Rise Farm this past weekend. The survey carried out was actually a repeat survey of one conducted two years ago which involved the use of seventy two traps which were operated over two nights. However, the results were somewhat different with previous findings revealing a high quantity of field voles, a moderate number of Wood and Harvest Mice, but only a small number of Shrews.
This year Field Voles were again relatively abundant, as were Wood Mice. A few shrews and Bank Voles, were also identified but sadly no Harvest mice at all. The best result of the weekend was to catch one Water Shrew; the largest shrew species and one that requires an abundance of aquatic invertebrates in order to thrive, something which the Bourn Brook can effectively provide. However, there was no evidence of Water Shrews in a special survey conducted last year. The last recording of a Water Shrew at Lark Rise Farm was back in 1999, when two were identified by Dr Bob Stebbing. Although his methods have been replicated by our monitoring officers since 2009, there haven’t been any sightings.
Dr Vince Lea states: “The high number of field voles is the reason Barn Owls have thrived this year, in fact on Sunday morning we were surprised to discover three Short-eared Owls in the field where we were doing the survey – they are probably Scandinavian migrants come to feast on our voles for the winter!”
The Water Shrew (Neomys fodiens) lives almost entirely in wetland habitats, in small burrows in the bank of rivers. It feeds on small invertebrate prey and despite not having webbed feet, it swims well underwater aided by a fringe of stiffer hairs on its back feet and hair on its feet.