Saturday, October 6, 2012

Mammal Profile Vol. 1: The Least Shrew

Whum chakka um chakka chumchakka whum!
Guosim dig yore paddle deep,
Hurly-burly river wide'n'curly,
There's no time to sleep.
Whum chakka um chakka chumchakka whum!
Rapid wild and fast do go,
Hurly-burly river wide'n'curly,
Bend yore backs an' row.
Whum chakka um chakka chumchakka whum!
Keep her bows up in the foam,
Hurly-burly river wide'n'curly,
Logboat take us home.
Whum chakka um chakka chumchakka ...

-Paddling Song, Guerrilla Union of Shrews In Mossflower, Marlfox by Brian Jacques

I'm not sure if you have read any of the books in the Redwall series by Brian Jacques, but as the main characters are mostly small mammals, you can bet I will shamelessly make references to the series during these mammal profiles (If you haven't heard of the series, it is similar to Watership Down).

So far during our trapping endeavors, we have captured 5 different species of small mammals. One of my favorites, the least shrew (Cryptotis parva, Greek and Latin for "small hidden-ear" shrew), is the first animal I'm going to discuss. The least shrew is in the diverse and complicated order Insectivora (insect-eating and carnivorous mammals). Within that order, they are classified in the Soricidae (shrew) family, a group containing some of the smallest mammals. Characterized by their small eyes, pointed teeth, and long tapered snout, this species relies mostly on its sense of smell and hearing to move and locate prey.

Least shrews are very vocal, using clicks and squeaks to communicate.
In this case, they are mostly communicating, "Stop weighing me and let me go."

The mammals are very small, growing up to 92 mm in length--including tail--and weighing up to 5.7 grams, the weight of a nickel. Although small, they are voracious eaters and busy critters. They are almost always active and only have short periods of rest. Part of this arises from an incredible metabolism: having to eat 50% of their weight or more every 24 hours. The least shrew consumes large amounts of arthropods, worms, and other insects. For some insects that are too large to consume whole, the shrew will eat out the insides. They also are a food source for many other animals, including snakes, raptors, foxes, and skunks.

While the least shrew is often confused with members of the short-tailed shrew genus (Blarina), the least shrew is distinguishable by its tail, which is less than half the length of its body and head. Behaviorally, the least shrew also is rather social, as nests can have up to two dozen individuals. These nests are usually found near logs, rocks, and debris, and they are made out of shredded grass and leaves.

 Unfortunately, due to their energetics, it is not rare to have shrew mortality.
Sometimes the shrew cannot survive the time in the trap, but all possible measures are taken to avoid it.

The old-field habitat in which we surveyed and found the majority
of our least shrews.

The least shrew is mostly found in dry, open grasslands, but they also are found in saltwater marshes.  Typically, the Sherman live trap is not the best method to capture shrews, but we set the trap's trigger to close at a lighter weight.

Linzey, D.W. 1998. The Mammals of Virginia. The McDonald & Woodward Publishing Company: Blacksburg, VA.
Webster, WM. D., J.F. Parnell, and W.C. Biggs, Jr. Mammals of the Carolinas, Virginia, and Maryland. The University of  North Carolina Press: Chapel Hill, NC.
Schemnitz, S.D., 2005. Capturing and Handling Wild Animals. In C. Braun (Ed.).Techniques for Wildlife Investigations and  Management (pp.239-285). Sixth Edition. The Wildlife Society: Bethesda, MD.


  1. Good old Jacques...

    Don't believe I've ever seen a Least Shrew before....only Sorex and Blarina species.

    Great capture!

    Just posted a bit on Shrews, myself.

    Great minds think alike, I guess...

  2. Wow, Brian Jacques-this makes me want to go back and read the series again.
    Interesting information. I'd like this shrew's metabolism. Looks very tiny next to your hand.
    If not the Sherman live trap, what is the best method of capturing them without harm?

    1. The least shrew is actually the smallest mammal in North America, so yes, it is very small next to my hand!

      Pretty much any live trap (traps that don't kill) will cause them harm if not properly baited or checked regularly. But, pitfalls, essentially buckets dug into the ground, are best able to capture shrews. The only other way to possibly prevent mortality is to check more frequently or to provide more food.