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Saudi Arabian Wildlife  Afghanistan Wildlife



In Which We Meet Those Species Particular to the Northwest

John M. Regan

        Although we have no hedgehogs in this part of the country the moist Northwest climate is a blessing to moles and shrews alike.  For moles the abundance wrung from the sky every year maintains the soil in ideal conditions.  Moist and permeable it is perfect for excavating and loaded with the gourmet delight of every mole – earthworms.  Shrews, who in general prefer forest floor leaf litter, find that our evergreen forests provide wonderful cover both above and on the ground throughout the year.  These same conditions ensure a fine supply of insects, worms, and the various other items that feisty little shrews depend on.

“Of Moles and Men: The Battle for the Turf”

        Looking out over the verdant fields and seeing the enormous upwelling of mole hills one might reasonably conclude that the mole population is the dominant insectivore activity in the land.  When population and number of species are considered, however, the shrew family is by far the most populous.  In fact shrews comprise 70% of all known insectivore species.  The following list of the insectivores in our part of the country is compiled from the American Society of Mammologists, Smithsonian Museum of Natural History, and Dr. Thompson’s “Of Moles and Men:”

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Shrews (family Soricidae):

·         Marsh Shrew Sorex palustris:                             5 – 7 inches; large shrew; Pacific Northwest coastal regions from Washington to northern California

·         Masked or Common Shrew Sorex cinereus :    5-6 inches; throughout North America largest range of any shrew (also called a Cinereus Shrew)

·         Merriam’s Shrew Sorex merriami:                      3-4 inches; found throughout arid parts of western US

·         Montane Shrew Sorex monticolus :                   4-5 inches; western North America from Alaska to Mexico (also called a Dusky Shrew)

·         Preble’s Shrew Sorex preblei :                           a very small (about 3 inches), relatively unknown shrew of the arid regions of the Northwest.

·         Trowbridge Shrew  Sorex trowbridgii:               4-5 inches; inhabits the coastal regions of the western US

·         Wandering or Vagrant Shrew Sorex vagrans:        Approximately 4 inches; moist regions from British Columbia and into northern California and Nevada

·         Pigmy Shrew Microsorex hoyi :                         2-3 inches; prefers the northern regions of Canada and into Alaska


Moles (family Talpidae):

·         Shrew Mole Neurotrichus gibbsii :                       4-5 inches long; smallest mole in North America and exclusively a Pacific Northwest inhabitant

·         Townsend’s Mole Scapanus townsendii:            8-9 inches long; largest mole in North America; exclusive resident of Washington and Oregon coastal regions with some extension into northern California

·         Coast Mole or Pacific Mole Scapanus orarius:    6-7 inches long; same range as the Townsend’s Mole but also inhabits drier areas to the east part of the Northwest

     So why the imbalance despite the overwhelming evidence of moles?  The main reason is habitat requirements.   Moles, so very dependent upon soil conditions are  therefore tied to the condition of that substrate.  Shrews, however, despite a similarly secretive life, live above ground and are able to tolerate a wider range of environmental conditions.  Shrews inhabit terrain from aquatic to quite arid environments.  Whatever the actual population numbers are for either species it surely is huge.  The author is not aware of any reliable population counts to date.    

What’s the Difference?

      Besides the fact that one vandalizes lawns and gardens and the other doesn’t there are several important physiological differences between shrews and moles.  Moles are generally larger and more powerfully designed.  After all, you have got to have real digging muscle and bone structure to plow through dirt the way they do.  Shrews on the other hand are smaller and do not possess the powerful front legs of their mole cousins.  In keeping with a life above ground shrews have external ears and prominent eyes.  A number of shrews have even developed a venomous bite. 

     To say that insectivores are fascinating beasts is an understatement of enormous proportion.  The smallest species of mammal in North America they may also qualify as the feistiest as well.  Their brief two to three years of life is filled with incredible activity and voracious appetites.  Moles have developed a skeletal structure that allows them to quickly power through their underground terrain with amazing speed.  They have hearing sensitive enough to hear an earthworm burrowing through the soil.  A number of shrews possess toxic saliva and even use echo location in a manner similar to bats.  One shrew is even at home in water.  Insectivores, even just those in the Northwest, are hardly done justice in the space of a single article.  But perhaps these few words have triggered your own voracious appetite for more information.    

The next time you are out for a stroll in the forest or just going no further than your front lawn, stop and take a look at the ground under your feet.  There’s a lot going on down there.



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Saudi Arabian Wildlife  Afghanistan Wildlife