The smallest mammal in the world is the bumblebee bat but the Eurasian pygmy shrew (Sorex minutus), a park resident, comes a close second.
They are tiny; the largest adult pygmy shrews are rarely more than 5cm long, including their furry tails, and they weigh about the same as a 20p coin. Despite their minute size they are aggressive, apparently fearless and very territorial.
They have an extraordinarily rapid metabolism; their hearts beat more than ten times in every second, and in order to produce the amount of energy that this requires, they must eat more than their bodyweight each day. They are voracious insectivores, hunting arachnids, beetles and woodlice at ground level, below the grass-mat or among the litter of a woodland floor. Unlike the common shrew, they rarely eat earthworms.
Pygmy shrews are very short lived; their maximum lifespan is around thirteen months. They overwinter as immature adults and breed between April and October the following year. In that single breeding season a female can produce two or three litters of young, each litter containing up to seven pups.
Mortality is high, particularly in the first six months of a pygmy shrew’s life. They hunt night and day, so inexperienced youngsters are a favoured prey of owls as well as daytime avian hunters like kestrels, magpies and other corvids. They also fall victim to stoats, weasels and foxes; cats hunt and kill them too, but often leave them uneaten because of the unpleasant smelling secretions from their scent glands.
Pygmy shrews are common and widespread and their population guessed to be in the millions and hoped to be stable although there is insufficient evidence to be absolutely sure. The main threat is the loss of unimproved grassland; it is another of those species we might well be tidying out of existence.
Conservation status: protected under the 1981 Wildlife and Countryside Act
More of the park’s mammals: