This month as summer draws to an end and autumn begins, shrew numbers are at their peak! They have had a busy few months of feeding and breeding, pretty much the two things they do best! In ideal shrew habitat, it is thought that around 70 individuals could inhabit a single hectare. The abundance of insects throughout the summer is the reason for this peak, but as we enter winter many shrews’ already short lives (average 15 months) are cut even shorter.
The Common Shrew has tiny eyes, small ears and very a large nose giving it an excellent sense of smell and a peculiar pointy face. It is dark brown above, grey or silver below, and has chestnut-coloured side. Shrews can be found living almost anywhere, but are most commonly found in hedgerows, scrubland, grassland and deciduous woodland. Shrews sleep in burrows; often moving into disused ones dug out by another small mammal, such as a mouse or a vole. Females have three or four litters of 5-7 young between May and September.
The Common Shrew’s main food source is insects but they will also eat earthworms, small slugs and snails, especially in damp areas. Shrews must eat every 2-3 hours to survive! Shrews hectically snuffle through the undergrowth for their prey.
Being a small mammal, Shrews are also an important prey to a number of predators. They are most commonly killed by tawny owls and barn owls, although weasels, foxes, stoats and kestrels have all been observed as likely predators. Cats are another significant predator, who kill the Shrews but then abandon them; as the Shrews in an attempt to protect themselves produce a foul tasting liquid from their skin.
As we enter the winter, give a thought to the tiny Shrews, who do not hibernate. Although they do become less active in winter and incredibly they shrink in size through the winter! Their spines get shorter, as well as their major organs, including the heart, lungs and spleen. Even their brain mass drops by 20–30%! This surprising survival strategy means they require less effort to move and so need less food. The evolution of modern-day shrews extends back almost unchanged for more than 48 million years. They're an incredibly successful group, belonging to an ancient lineage of insectivorous mammals, some of which were remarkably 'shrew-like' and shared the planet's surface with the mighty Dinosaurs of the Jurassic.