shrew Archives

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.

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

We humans don’t always like the winter snow for its inconvenience and sometimes safety threat. For many animals, the snow-cover makes winter the best time of year. Scientists who study life in this seasonal microenvironment under the snow call it the subnivium ecosystem. It allows many species of plants and animals to exist that could not survive without snow.

The first scientific writings about the subnivium world were circulated by a lepidopterist (a scientist who studies butterflies) named Vladimir Nabokov. Nabokov was investigating butterflies whose caterpillars eat plants known as blue lupines. These butterflies lay their eggs on the stems of the lupines a few inches above the ground. When snow covers the area, the eggs are protected from the very low temperatures of the mountains where the butterflies live. Scientists conducted a study of those same butterflies in 2019 when there was a significant decrease in the snow cover. They found a 43% decrease in the number of butterflies produced.

This is just one example of life in the subnivium ecosystem. Ruffed grouse burrow into the snow at night and stay in an igloo-like area that can be 50 degrees warmer than the outside air. In wintertime, a surprising number of animals live in the warmer subnivium ecosystem. Wolverines, martens, voles, mice, shrews, red squirrels, and even bears take advantage of heavy snow cover. The protection of snow allows abundant life at high elevations and in polar areas.

Every part of Earth is home to living things because of the design of the animals and plants and the design of water that gives snow thermodynamic properties. It is easy to overlook the statement God made to Job about “the treasures of the snow” (Job 38:22). The simplicity of those words describes a whole world of life in the subnivium ecosystem and the treasure of water stored on snow-covered mountains. The treasure house of snow speaks of the intelligence built into every corner of creation.

Data from National Wildlife magazine, February-March 2021.

Tag: shrew

Tiny and Incredible Shrews

Subnivium Ecosystem Harbors Life