Little Tiny Predators

     Shrews are, arguably, the smallest mammals in Pennsylvania.  Weighing in at less than an ounce, these insect eaters are often confused with their cousins the moles.  Moles hunt for insects and earthworms underground, burrowing through the soil and rarely coming out above ground.  Shrews, on the other hand, hunt above ground, although they do tunnel through snow and fallen leaves.
     Moles are known for the tunnels and mole hills that they leave behind.  The presence of shrews is only visible in the winter when there is snow cover.  The amount of shrew evidence can be astounding, as we have found this winter at Lutherlyn.

     In the picture above, you can see a shrew trail entering a tunnel in the snow.  The trail and tunnel are about 5/8" wide.  In the photo below, you can see a shrew trail crossing a gray fox trail.  The fox print is about 1 1/2" wide.

                                          

     These tiny predators are amazing for their size.  They live fast and die young.  A shrew's heart may beat 1,200 times in a minute!  With a metabolism like that, it is no wonder that they have to eat almost constantly.  Young shrews reach adulthood in four to six weeks after birth.  However, shrews rarely live for longer than one year.  They are easily killed by floods, sudden temperature changes, starvation, and even fright.  Predators also kill some, but most are not eaten since shrews give off a musky odor that most predators do not find palatable.

     One of the shrew species that lives in Pennsylvania, the northern short-tailed, has toxic saliva.  When it bites prey, the shrew's saliva can slow down or even kill the insects, worms or other creatures that it wants to eat.
     It has got to be hard to find enough food in the winter to keep that little body going.  I suppose that explains all of the tracks that we find throughout the forest.  These animals have to spend most of their day trying to find enough food to keep their little heart beating.  One of the benefits of this long winter is that it has made me take notice of how animals survive bitter cold and snow.  It has really made me appreciate many of these creatures that we seldom see, but are supremely adapted to survive (and thrive) in a long cold winter.