Tiny and Incredible Shrews

You may not have seen them, but thousands of shrews scurry across the ground, helping keep your garden free of destructive insects, snails, and slugs. Tiny and incredible, shrews are North America’s smallest mammals. They are smaller than a human thumb and have hearts that beat 1,200 times per minute.

There are 39 shrew species in North America, and many more worldwide. There is even one that can walk on water thanks to stiff hairs on its feet. That species feeds underwater using bubble sniffing—a technique of blowing small air bubbles through their noses to detect odor particles in the water.

Shrews are not rodents but insectivores, similar to hedgehogs. Their coat helps them camouflage amid leaf litter and debris. They have scent glands on their sides that emit a foul odor to deter predators such as cats, raccoons, and foxes. Like bats, they can use echolocation to find food.

A shrew’s metabolism is so high that it must eat roughly once an hour, and it only sleeps for a few minutes at a time. Though they don’t hibernate, they make tunnels beneath snow or ice layers. One remarkable trait of the tiny and incredible shrews is that they can actually shrink their head size, including their brains, by 20% during cold weather. Since food becomes scarcer in winter, shrinking their heads and brains helps them require less food. Their head size returns with warm weather.

Shrews are among God’s most useful creations because they help control snails, slugs, insects, and ticks, protecting plants and people. Only in recent years has technology enabled us to study the tiny and incredible shrews.

— John N. Clayton © 2025

Reference : Linda Weiford in The Spokesman–Review, December 1-8, 2025.