Species in the Spotlight: Common Shrew

Fri 11th Jul, 2014

One of the most abundant yet overlooked mammals on the Yorkshire coast is the Common Shrew. Most people see shrews only as corpses, or at best catch a fleeting glimpse of one running across a track. Such observations can be partially explained by the shrew’s extremely high metabolism. Life in the fast lane means shrews, with bodies that require 90% of their own weight to be consumed every 24 hours and meals no more than two or three hours apart, seldom live beyond 15 months.  No wonder they are either seen fleetingly or dead!

This tiny insectivorous species has made its home in the grasslands and woodlands of Europe for approximately 1.5 million years. Like other small mammals, the young are born blind, bald and deaf and are completely dependent on their mother's milk for survival. Common Shrews generally have one to two litters per year, with three or four in particularly good years (such as 2014). Each litter typically consists of six to seven young, which remain within the nest until around 16 days of age, when they emerge and travel around the nest. Usually these juveniles will remain in an adolescent state over the winter before becoming sexually mature around the following March, when most will start to breed.

Due to their incredibly small size and high metabolic rates, shrews are physically unable to store sufficient fat reserves to survive the winter and therefore don’t hibernate. Surprisingly for an insectivorous mammal, winter survival rates are generally quite high, often more so than rodents in similar habitats. Natural death in older animals usually occurs in summer and is attributed to wearing of the teeth, inability to moult and competition with that year’s young.

Dan Lombard