Güldenstädt's shrew

Fascinating facts about the Güldenstädt's shrew

• A shrew's heart beats 1,200 times per minute — that's 20 times faster than yours — which means it must eat almost its entire body weight in food every single day just to stay alive. Güldenstädt's shrew weighs about 7 grams, so it consumes roughly 6 grams of insects and earthworms daily. Miss even one day of feeding and it starves to death. This metabolic frenzy is why shrews are among the most aggressive hunters in the forest despite being smaller than a mouse.
• Most mammals navigate by sight or smell, but Güldenstädt's shrew hunts almost entirely in the dark using ultrasonic echolocation — clicking sounds at frequencies up to 60 kHz that bounce off prey and echo back to their brain. This ability was only confirmed in shrews in 2004, decades after scientists first noticed the clicks. In the thick leaf litter of Eastern European forests where they live, echolocation outperforms eyesight, letting them hunt invisible prey buried centimetres underground.
• Female shrews carry their young in a living chain: each pup grabs the tail of its mother or older sibling in its mouth, and the entire line moves together through tunnels and under logs as a single unit. If one baby loses grip, the chain breaks and the separated pup will starve within hours — there is no going back. This tether system keeps litters of 5 to 10 babies bonded to their mother while she hunts, a survival strategy found nowhere else in mammals.
• Güldenstädt's shrew produces venom in its salivary glands — unusual for mammals — which it injects into prey through grooved teeth. The toxin is weak compared to venomous snakes, but it numbs earthworms and insects just enough to slow them down, giving a 7-gram predator crucial seconds to subdue prey that might otherwise escape. This venom was likely inherited from a distant common ancestor, making shrews living fossils of mammalian weaponry.
• In winter, Güldenstädt's shrew's brain shrinks by up to 20 percent, then regrows in spring — a dramatic neural reset that reduces its metabolic demands when food is scarce. This shrinkage is reversible, happening in no other mammal at such a scale, and scientists still don't know how the brain manages to restore its full size and function. It hints at hidden plasticity in mammalian neurology that could one day reshape how we understand the brain's limits.

At a glance

About the Güldenstädt's shrew

In the shadowy undergrowth of eastern Europe's forests, the Güldenstädt's shrew darts with frenetic energy, its tiny paws a blur as it pursues the hidden world of insects and invertebrates. With a twitching snout and an insatiable appetite, this diminutive hunter navigates the dense thicket of roots and leaf litter, its sleek, grey-brown coat blending seamlessly into the dappled gloom. As it forages, the shrew's high-pitched squeaks pierce the air, a testament to its fearless and unrelenting drive to survive in this secretive, subterranean realm.

Discover more wildlife