What Do Shrews Eat?
Posted In: Mammals.
Insects make up the biggest part of a shrew’s diet. There are several dozen types of shrews in the world, some of which weigh as little as two grams. Despite their diminutive size, however, they are ferocious predators and will take on and kill animals as big – or even bigger – than themselves. Shrews will often go for insects like beetles, butterfly and moth larvae, grasshoppers and even wasps.
The elephant shrew and the northern short-tailed shrew.
A Shrew’s diet
As well as bugs, shrews will also kill earthworms, spiders, slugs and snails, as well as centipedes. Larger shrew species can even kill mice, birds and snakes. The northern water shrew will eat fish eggs, and even the adults of the smaller fish types they come across. There seems to be no end to the bravery of this rodent, as some types will even enter beehives to eat honey – and the occupants! In hard times, shrews aren’t too proud to kill and eat their brethren.
Some species of shrew add to the meat part of their diets by eating vegetables like roots and seeds. The vagrant shrew especially likes Douglas fir seeds, and the masked shrew enjoys white spruce seeds and lodgepole pine if it’s available. Fungi is also on the menu at times. America’s most common shrew species, the northern short-tailed shrew, is fond of an underground fungus called endogone.
How much do they eat?
The northern short-tailed shrew needs to eat up to three times its own body weight every day, with other species eating up to three-quarters of its weight daily. This is because they have a very fast metabolism which needs stoking constantly – at least every two hours. A shrew will starve if it doesn’t eat for five hours, so it’s not hard to imagine how these tiny mammals must strive for food constantly. Shrews don’t hibernate in the winter, instead they can slow their metabolism down a bit. Their bodies are simply too small to hold enough fat reserves to see them through the snow.
The northern short-tailed shrew belongs to the Blarina genus, and its cousins, the southern short-tailed shrew and the Elliot’s short-tailed shrew have toxic saliva. This poison won’t affect humans, but can take out a snail or an earthworm. The clever shrews will incapacitate them with a bite, and then save the paralyzed creature for later. The animals don’t die for a while, so will stay fresh in the shrew’s larder!
It can kill cancer cells!
The toxin, called soricidin, is under a lot of investigation at the moment, as it appears to have the ability to kill cancer cells. Originally thought to be of use as a painkiller, as it blocks nerve transmissions, soricidin may prove to be a wonder drug in the fight against this most hated of human ailments.
Shrews’ natural predators
Of course being so small, the shrew is itself quite low down in the food chain. Owls are notorious predators of shrews, swooping upon its prey and delivering a swift death with their talons and beaks. Shrews are also eaten by foxes, snakes and bobcats. Domestic cats will also hunt and toy with shrews, but often won’t actually eat it.