Newsletter #190 What’s That Shrill Squeaking Around the House at Night? 🐭✨
Newsletter about nature and science
What’s That Shrill Squeaking Around the House at Night? 🐭✨
Chances are, a common shrew is scurrying through your garden, making its presence known. The common shrew is the most widespread shrew species in our country. Only on Vlieland and Terschelling do they have to do without them.
Despite their name, shrews are not actually mice — they belong to the insectivores, like moles and hedgehogs. What is true, is that they have a pointed, very mobile snout. Another frequent relative is the forest shrew, which looks quite similar at first glance. Yet, tens of millions of years separate the two species.
One belongs to the white-toothed shrews (subfamily Crocidurinae). These shrews, including the common shrew and the field shrew, are mostly nocturnal. When resting — especially in the morning or during winter — they can lower their body temperature to below 18°C.
This kind of daily mini-hibernation is called torpor.
The other lineage, around 20 million years older, are the red-toothed shrews (Soricinae). In our country, this group includes the forest shrew, the water shrew, the pygmy shrew (an adult weighs only 5 grams!), and the bicolored white-toothed shrew.
These species, with their orange-edged sharp teeth, are always warm and active — day and night — following a steady rhythm of one hour active, one hour resting.
Small but Intense ❤️🔥
Shrews are tiny mammals — none of the Dutch species weighs more than 15 grams. That means they lose heat quickly and have an extremely high metabolic rate. Their oxygen consumption is huge, their heart rate can reach up to 1,000 beats per minute, and their energy needs are sky-high.
The body temperature of red-toothed shrews averages 38.5°C, while white-toothed shrews run about two degrees cooler. All in all, they live fast and die young — rarely older than two years.
It’s a remarkable evolutionary story: two completely different strategies to survive such a demanding metabolism. One: stay active around the clock. The other: adopt a nocturnal rhythm and drop body temperature by over fifteen degrees during rest. Both have been successful for tens of millions of years.
Not Primitive at All 🧬
The idea that shrews are “primitive mammals” is simply wrong. They appeared 30 million years after the dinosaurs went extinct. It’s true that during the age of the dinosaurs, only small, “shrew-like” mammals survived by hiding in the night — but as we now know, they were not related to our modern shrews.
Diet and Predators 🐞🐍
Shrews eat mainly animal food — spiders, slugs, woodlice, worms, and insects, including larvae like leatherjackets (the underground larvae of crane flies). But they won’t shy away from a young mouse or a small frog either.
The water shrew, with its dark glossy coat, always lives near water and even eats small fish. On average, shrews consume their own body weight in food every day.
They have few predators — mostly tawny owls, barn owls, stone martens, foxes, and occasionally even wolves.
Most animals are deterred by their strong odor. Cats will catch and kill them, but never eat them — instead, they proudly bring them home as “gifts.” They’re rarely thanked for it.
Those Shrill Sounds 🔊
The high-pitched squeaks shrews make (some even use ultrasonic frequencies for echolocation) are thought to serve primarily for communication — and maybe also as a warning: Watch out, cats nearby! Or perhaps: Watch out for their owners.
💡 Observation Tip
1️⃣ Listen carefully at night.
2️⃣ Remember: catching or killing shrews is strictly forbidden — they are a legally protected species. We now have three publications:
Dutch podcast on wednesday
Nieuwsbrief NL → dutch newsletter
Newsletter ENG → same newsletter but in english
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