The masked shrew - a new superhero?

 

Masked shrew I found near Leduc, Alberta

You've heard of the Masked Avenger, the Masked Marvel, perhaps a pelagic bird called the masked boobie, well, this miniature mammalian marvel outdoes them all - meet "The Masked Shrew".  Although tiny, it possesses a terrific appetite.  Due to its incredible metabolism, it must consume somewhere between one and three times its body weight in food a day.  Imagine a human doing that (besides a teenager).  A 150 pound person eating 450 pounds a day - amazing!

The menu is no less incredible (oops - I already used that word) - astonishing.  Insects, slugs, snails, spiders, earthworms, and even small vertebrates such as salamanders, moles, and mice.  A shrew that can attack and overwhelm another mammal larger than itself, kind of like a mink overcoming a rabbit.  Indeed, another superhero trait.

If you thought the unbelievable properties are done, imagine such a tiny creature, a mammal at that, having venom.  Yes, certain shrews have a venomous bite to help overcome their victims.  Venom in a mammal is rare; some bats, moles, and even a primate or two use it.  The masked shrew itself does not use venom, but its close relative, the northern water shrew, does.  The venom is carried with the saliva and is delivered to prey when a bite occurs.

These marvellous creatures have heart rates approaching that of hummingbirds at around 1000 beats per minute.  They are active all year round, even in cold climates such as Alberta.  They will hunt underground, in leaf litter, or under snow cover in their search for food.  When food is scarce, they may enter a state of torpor where their metabolism slows down.  Their skeletons may even shrink in an effort to conserve energy.

If you didn't notice, the shrew above is dead.  I found it on a bike path one morning near Leduc, Alberta, where we were camping.  They live a maximum of two years, an average of about 14 months.  They are highly predated, starve easily, and their small bodies just give out due to their tremendous metabolism.  Shrews may breed several times a year and may have anywhere from 2 to 10 young.  Their high rate of reproduction helps maintain their population.  You've heard of breeding like rabbits?  Imagine breeding like shrews!

Thanks for reading.

Eric Svendsen     www.ericspix.com