Pygmy shrew  (Sorex minutus)

Pygmy shrews are active by day and night, interspersing bouts of activity with rest periods (5). They are typically solitary, and will defend their range against other pygmy shrews (4). They make surface tunnels through vegetation (4), and feed on invertebrates such as beetles, spiders and woodlice that can be found in the leaf-litter (5), but they very rarely tackle earthworms, possibly because they are too large for them to handle (2). Shrews are well known for their voracious appetites; due to their small size and high metabolic rate, they have to eat regularly, and consume about 125% of their own body weight in food each day in order to stay alive (2). They do not hibernate, as they are too small to store the fat reserves needed to sustain them, instead they have to remain active during winter (2). Births occur between April and August, peaking in June (5). Two litters are usually produced each year, each consisting of between 4 and 7 young (5). The young overwinter as immatures (4), reaching sexual maturity the following year, although some females born early in the year may even breed in the year of birth (5). Main predators of pygmy shrews are owls, raptors, mustelids, foxes and cats. The maximum life span is 16 months (5).

Shrews belonging to the genus Sorex are known to produce ultrasound, which may be used in a primitive form of echolocation(6).