Field signs
Being so small the pygmy shrew leaves very few signs. They are rarely heard in the wild as they are less vocal than the common shrew. The small spherical nest is sited underground or under dense cover. Droppings are sometimes found in water shrew bait tubes and can be recognised by their high content of spider remains, giving a brown appearance under magnification.
Habits
The pygmy shrew is widespread in all types of habitat but prefers dense ground cover and is more commonly found in grassland than woodland. It usually lives at a lower density than the common shrew with a larger home range. It spends most of its time on the ground, but will climb up into vegetation and trees and is even able to swim well. Unless searching for a mate, it is usually solitary and aggressive towards its own species. It is active day and night with frequent short rest periods. The main prey items are woodlice, spiders, beetles and harvestmen. Unlike the common shrew it does not dig for prey under the soil, but uses its mobile snout to forage in leaf litter and vegetation for more than 250 prey items per day. It is a poor burrower so uses the burrows of other small mammals and makes surface tunnels through vegetation. It spends less time below ground than the common shrew. Predators include owls, kestrel, stoat, weasel, fox and the domestic/feral cat but its two scent glands exude a deterrent musty odour which often causes it to be abandoned after being killed.
Pygmy shrews have been regularly found in Kent dormouse nest boxes at sites such as Spong Wood. A nest of four young was found in a rot hole in a tree that was felled outside Westwell Village Hall in 2012. They are often brought in by domestic cats and are commonly found in barn owl pellets as owls have a poor sense of smell and so are not put off by the scent glands.
Reproduction and life cycle
Pygmy shrews breed from April to October. Females rear up to 3 litters per year of 4 - 6 young per year, with a 20 to 25 day gestation period. Juveniles overwinter then become sexually mature the following spring. They have a very hairy tail when young but most of this hair is lost as they reach maturity. Mortality of young is high but adults can live for 13 to 16 months.
Distribution, status and conservation
The pygmy shrew is widely distributed throughout Britain including many islands and is the only native species of shrew found in Ireland. It has partial protection under Schedule 6 of the Wildlife and Countryside Act 1981 (as amended) regarding trapping, killing and using invasive procedures. It is often trapped in small mammal surveys in Kent but is not encountered as frequently as the common shrew.
With its small size and high metabolic rate it can easily die from starvation, cold or stress in traps if they are not checked frequently or provisioned well. The main threat to this species is habitat change. Modern farming practices have resulted in fewer hedgerow corridors, with herbicide and insecticide spraying having reduced diversity of wildflower meadows and invertebrate populations.
