The Pygmy Shrew (Sorex minutes)
Recognition: A very small mammal with markedly pointed snout. As in the common shrew the fur is greyish brown (dirty white ventrally) but the pygmy shrew is smaller and has a proportionately longer and thicker tail. Head/body length: 40-60 mm; tail 32-46 mm Weight: 2.4-6.1 g. Weight may decrease up to 28% in winter. Lifespan: Peak mortality is at 2-4 months and the maximum lifespan is around 13 months.
Diet: They feed mainly on insects, arachnids and woodlice, requiring regular meals and eating up to 125% of their body weight in food daily. Unlike common shrews, they rarely eat earthworms.
Widespread throughout the mainland of Britain and Ireland, in most terrestrial habitats which offer sufficient ground cover. They are also found on the Isle of Man and Outer Hebrides, where common shrews are absent. Pygmy shrews are active day and night, largely above ground. They make and use "surface tunnels" in vegetation and will frequent burrows dug by other animals. They seem to be relatively more common on moorland than are common shrews. As in all shrews, senses of smell, hearing and touch are well-developed.
Pygmy shrews are solitary and aggressive towards co specifics. Home ranges vary from around 500-2000 square metres, depending on habitat, with maximum densities of around 12 per hectare. Strict territoriality is only abandoned during the breeding season.
Pygmy shrews over winter as immature and breed between April and October, producing two or three litters of 5-7 young. Their main predators are owls and other avian predators, particularly those which hunt on moorland.
Shrews are protected under the 1981 Wildlife & Countryside Act. As with all shrews, they may be trapped only under licence. In any trapping study on small mammals, care is necessary to avoid killing shrews, which are extremely susceptible to death by starvation due to their small size and correspondingly high metabolic rate. Traps should be provided with suitable food (e.g. mealworms, meat) and/or visited at least every 2 hours. The main habitat requirements are vegetation cover and invertebrate food.
Harris, S. & Yalden, D.W. (2008) Mammals of the British Isles (4th edn.). The Mammal Society, Southampton.Gurnell, J & Flowerdew J.R. (2006) Live Trapping Small Mammals: A Practical Guide. (4th edn., revised). The Mammal Society, Southampton.