ALL CREATURES GREAT & SMALL
In his new series, Patrick Barkham celebrates the longstanding residents that make up this country’s rich fauna
In his new series, Patrick Barkham celebrates the long-standing residents that make up this country’s rich fauna. This month: shrews
IT IS A MAMMAL, not a rodent, has a nose like a miniature anteater, minuscule eyes, soft downy fur and must eat its own bodyweight in food every day to survive. The extraordinary character of the shrew is often overlooked – easily done when you’re Britain’s smallest mammal. The pygmy shrew is a tiny creature that fits comfortably in the palm of your hand and weighs no more than a 20p coin.
If you have ever encountered one of these, or its larger relative, the common shrew, it will likely be because it has been presented to you as a gift by a pet cat. Interestingly, the reason felines are so generous with these animals is due to their smell, as revealed by biologist Professor Jeremy Searle:“the scent of male shrews will stay on you for a long time. When I began studying them, it was lucky I already had a girlfriend.” This odour makes shrew flesh unpleasantly pungent for mammalian predators, and so cats rarely eat them.
Searle’s interest began as a biology undergraduate student on an expedition to study the shrews of Sweden. He had to feed earthworms to captive shrews because, unlike mice or voles, they are insectivorous, devouring worms and, occasionally, other small mammals, too. While on the trip, Searle stopped by a compost heap and spotted a shrew partially hidden in the undergrowth. After carefully trapping it, he discovered that, by sheer chance, he’d caught a taiga shrew, a species that was new to Sweden. “I knew I was blessed and destined to work with them from then on,” he laughs. “Maybe I’m peculiar but they are attractive to me. They are very different from rodents because they have these long noses and a plantigrade gait, which means they walk on the soles of their feet. And they look a little bit archaic, which I find appealing.”
A VORACIOUS APPETITE
There are scores of species of shrew around the world but just three in Britain: the pygmy, common and water shrew. These shortsighted animals, which are most often found among the
roots of hedges, woodland or in long grass, are more closely related to moles than rodents and their lives are defined by a desperate need to eat. “They are fast-food animals,” Searle explains. Unlike herbivorous mammals, which have a long gut through which they slowly extract nutrients from food, shrews have a short, simple tube-like digestive system. They need lots of high-energy food, which passes quickly through them. Day and night, and in all weathers, they scurry in their search for sustenance, using their whiskers to navigate, assisted by their constant twittering – something they use to echolocate, in a similar way to bats. This energetic lifestyle further increases their metabolism.
IMMORTALISED IN LITERATURE
It is this urgent requirement for food that makes shrews aggressive, and has given them a distinctive cultural status. William Shakespeare’s The Taming of the Shrew is a rather misogynistic comedy in which Petruchio woos and ‘tames’ Katherine, the ‘shrew’ who is a strong-willed, stubborn woman. ‘Shrew’ has been used in a pejorative sense in English, mainly to describe a bad-tempered, nagging harridan since the 11th century. In the 18th century, the term was defined by Samuel Johnson to mean “a clamorous, spiteful and rude woman”. This seems somewhat unfair on the little shrew, but Searle reveals it may be rooted in our ancestors’ close observation of the real animal. “In the breeding season, a female that is not in the mood for mating can become very angry with an interested male. You don’t want to leave them together in captivity – the female would probably kill the male,” he says. “Shrews shout at each other and when you catch them, you will often see scars on their tails from fights. They will also eat each other. These animals need food all the time – they don’t think too hard about what it is.”
The “Hannibal Lecter of the small mammal world”, the shrew’s voracious appetite was witnessed by the naturalist Mike Pratt, who spotted a greater white-toothed shrew “chewing on a rabbit leg, blood and fur spattering all about” on the Channel Island of Alderney. The three British species belong to a sub-family called the red-toothed shrews: their teeth are tipped with colour due to a deposit of iron in the enamel that hardens them so they can chomp through tough insect exoskeletons. But there is another group known as the white-toothed shrews. These have a slower metabolism and their teeth are white because they don’t need to crunch so many insects. The greater white-toothed shrew lives on several Channel Islands, having been accidentally introduced there by humans. Shrews are smart travellers: pygmy shrews have also hitched a lift to the Orkney Islands but not Shetland – yet. “Pygmy shrews get everywhere,” Searle says. “People quite often find them in their attics. They are
slippery little animals and very good climbers. It’s not surprising that they get into boats.”
Stowaway pygmy shrews have also reached Lundy in the Bristol Channel, where they’ve been studied by Nathaniel Legall, one of a young generation of shrew scientists. “Shrews are not a ‘rockstar’ group of mammals. They are traditionally associated with being quite vicious, and people say if you hold them they’ll bite but I haven’t experienced that,” he says. “They are fantastic to study because they are so difficult to study. The challenge of following this ninja-like mammal definitely appeals to me.” URBAN RESIDENTS
Surprisingly, shrews are found in cities, too, and Legall, a London Wildlife Trust ranger, is now recording common and pygmy shrews on Walthamstow marshes in east London. In west London, 100 London Wildlife Trust volunteers make up Vole Patrol, which humanely traps and records small mammals, including common and pygmy shrews, in Ealing, Hounslow and Hillingdon. “They’ve got a cool personality – feisty, not that different to myself,” says Vole Patrol leader Huma Pearce, who studied tree shrews in Indonesia. “They are survivors, constantly on the move.”
For all this tiny mammal’s fearsome reputation, shrews are best known for one endearing trait: the shrew caravan. If a white-toothed shrew mother senses her babies are in danger, she will instruct them to each take another’s tail, forming a train of young – akin to children holding hands on a school outing – and will then lead them to safety. “It’s the shrew equivalent of a game of ‘follow-my-leader’,” Nathaniel Legall says. “That’s pretty cute.”
The pygmy shrew (this page) is smaller and has a narrower snout than the common shrew (previous page and opposite)
A water shrew (this picture) forages for food in rivers and ponds; juvenile common shrews (below left) have lighter-coloured coats until their first moult