Shrews: Ubiquitous but rarely seen
by Gerry Los Banos
Many people have probably encountered a Shrew without their even knowing it. This is probably because from a distance, the tiny Mammals resemble Mice or Rats, and so are often mistaken for those more familiar critters. But those who get an opportunity to have a good look would realize that their noses are shaped differently from those of Mice — longer and more pointed, and more flexible. Few are sharped-eyed enough to actually spot one in the wild, though.
Shrews move quickly and are very good at staying out of sight by using tunnels they form in tall grass or sticking close to walls and fences when scurrying out in the open. The only times I’ve actually seen one in the wild are when I’ve come upon their remains on a sidewalk or lawn after they’d been killed by a Cat or had died due to other causes.
The most common type of Shrew found in the Philippines is Suncus murinus, usually called the Asian House Shrew. They are the largest of their family and are believed to have originated in India before human activity dispersed them to other parts of Asia. In China, they are sometimes called Money Shrew, because of the sound they emit, which is said to resemble the jingling of coins.
Suncus murinus is also well-known, especially on the ‘Net, for their habit of forming a “caravan.” When a mama Shrew moves her young to another location, the baby Shrews form a conga line of sorts behind her, with each baby (or “pup”) grasping the tail of the one in front between their teeth as mom leads them to a new nest or takes them exploring. One can easily find videos of this adorable behavior on Youtube.
Somewhat less adorable are a Shrew’s feeding habits. Though they may resemble Mice in some ways, their teeth are markedly different. Instead of the flat, chisel-like incisors that Mice and other Rodents possess, a Shrew’s teeth are pointed and sharp, better suited for clamping down and keeping hold of wriggly Invertebrates than chomping down on plant matter. Shrews are insectivores and belong to the same family as Moles. Like their burrowing relatives, they prefer to feed on live prey. Some Shrews, in particular the Etruscan or Pygmy Shrews (Suncus etruscus) who hold the record as the smallest living Mammal, have such high-energy demands that they need to spend most of their waking hours hunting as they must eat every few hours. They can consume as much as three times their body weight a day in order to maintain their extremely high metabolism. The Estrucan Shrew has a heart rate that can reach 1500 beats per minute, which is higher than that of any other Mammal. Shrews in general prey mostly on invertebrates like Worms and Insects, but have been known to attack and overcome small Mammals such as Mice or Voles and even small Snakes. The Asian House Shrew has been observed to have attacked and killed Rats almost twice their size, dispatching them with a bite to the back of the neck.
Some Shrews have such highenergy demands that they need to spend most of their waking hours hunting as they must eat every few hours.
Putting two Shrews together in the same place will usually result in at least one dead (and likely eaten) Shrew.
To aid in their hunting and navigation, Shrews are believed to have developed a form of echolocation. Remember the “jingling coins” sound they make? Some researchers think they emit this while moving in order to better find their way around as well as to locate potential prey the way Bats do. Studies that have attempted to verify this have been inconclusive, however. Some Shrew species like the North American Short-tailed Shrew (Blarina brevicauda) have been found to possess a venomous bite. They secrete poison from salivary glands in their lower jaw that can paralyze small prey. Some paralyzed prey have been known to stay alive but helpless for several days, allowing the Shrew to hoard a “larder” of live food that stays fresh. Fortunately, for us humans, this venom causes only swelling and irritation. It is still not advisable to attempt to pick up a Shrew however, as they can be quite aggressive, especially when cornered.
SOLITARY AND SMELLY
Shrews of any type are solitary creatures. The only time they come together is when they mate or raise their offspring. They are also highly territorial, so putting two Shrews together in the same place will usually result in at least one dead (and likely eaten) Shrew. Several Shrews, including the Asian House Shrew, have scent glands on their throat and behind the ears that produce a musky odor that most other mammals (humans included) find unpleasant. This is the reason one may sometimes find fully intact the corpses of Shrews killed by Cats; after dispatching the tiny creatures, most predators are deterred from eating them because of the smell. Many potential predators will avoid Shrews altogether due to the foul odor. The strong scent may also announce the Shrew’s presence in their designated territory and serves as a deterrent to other Shrews who might enter the area.
THRIVING IN THE WILD
Shrews as a whole rank near the front of the line when it comes to being among the most widespread and successful of wild animals. They are abundant and widespread over five continents and occupy almost every ecological niche, even rivers and streams (some Water Shrews can actually scamper across the surface of small bodies of water and are expert divers).
With the exception of a few species such as the Golden-rumped Elephant Shrew (Google “Elephant Shrew” and you’ll understand how they got their name) in Africa, Shrews are not considered endangered. Rough estimates suggest that there are well over 100 million Shrews scattered around the globe.
If you’re reading this while seated anywhere near a garden or even just a patch of grass, chances are there’s a Shrew of some sort in your vicinity. It’s a little ironic how this exceedingly common animal is seen only by a few and recognized by even fewer. This makes one realize how we should carefully observe our surroundings in order to better appreciate the amazing creatures we share our planet with.
Manila Bulletin Publishing Corp