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Northwest Wildlife Online
Order Rodentia:
Porcupines, Beavers, Squirrels, Woodchucks, Gophers, Marmots, Mice, Voles - and a cast of thousands
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The Eastern Gray Squirrel
Sciurus
carolinensius. Like most rodents the Eastern Gray has reaped great
rewards from man. Smaller than the Western Gray (Sciurus
griseus) he is distinguished from his western cousin by a slight yellow
tinge on the sides. Western Grays tend to bark when excited, while the
Eastern Gray makes a low growl; almost a moaning sound. On the right is
our largest rodent, the Beaver, Castor canadensis. Fascinating to
watch and hard not to love beaver have incredible impact on the environment,
some of them not so desirable if you happen to be a human landowner.
A surprisingly noisy - and surprisingly smelly - rodent, the New World Porcupine, Erethizon dorsatum, is our American representative of a family called Hystricidae. About twenty species of porcupines are found in Africa, Asia, Europe, and Indonesia. Porcupines, in fact, are found in more places than they are not. The American porcupine shown above is widespread throughout the United States and Canada. These guys carry on with a great deal of grunts and growls and a pronounced skunk like odor. Infamous for their ability to destroy trees they eat leaves, twigs, and bark and have a well known fondness for salt. Although they spend the majority of their time in trees, porcupines do find dens and burrows during extreme conditions. The end of the rodent's quills are lined with microscopic barbs that flare out when imbedded in an some creature unfortunate enough to get stuck
with them.
These pictures from Northwest Trek show a beautifully hard to resist beaver family. There are actually three kits snuggled in there born March 2007.
Three Suborders, 9 Families, and approximately 72 different Species of Order Rodentia represent wildlife in the Northwest:
Squirrel-like Rodents - Suborder Sciuromorpha:
Mountain Beaver Family - Aplodontidae
Squirrel-like Family - Sciuridae
Pocket Gopher Family - Geomyidae
Kangaroo Rat Family - Heteromyidae
Beaver Family - Castoridae
Mouse-like Rodents - Suborder Myomorpha
New World Rats and Mice - Cricetidae
Old World Rats and Mice - Muridae
Porcupine-like Rodents - Suborder Hystricomorpha
New World Porcupines - Erethizontidae
Coypu and Hutia Family - Capromyidae
Species List:
Mountain Beaver Family - Aplodontidae
Mountain Beaver
Beaver Family - Castoridae
American Beaver
Squirrel-like Family - Sciuridae
Yellow Pine Chipmunk
Least Chipmunk
Allen's Chipmunk
Townsend's Chipmunk
Siskiyou Chipmunk
Red-tailed Chipmunk
Antelope Squirrel
Townsend's Ground Squirrel
Columbian Ground Squirrel
Merriam's Ground Squirrel
Piute Ground Squirrel
Washington Ground Squirrel
Wyoming Ground Squirrel
California Ground Squirrel
Belding's Ground Squirrel
Cascade Golden-mantled Ground Squirrel
Golden-mantled Ground Squirrel
Western Gray Squirrel
Eastern Gray Squirrel
Eastern Fox Squirrel
Douglas's Squirrel
Red Squirrel
Northern Flying Squirrel
Woodcuck
Yellow-bellied Marmot
Hoary Marmot
Olympic Marmot
Pocket Gopher Family - Geomyidae
Northern Pocket Gopher
Western Pocket Gopher
Camas Pocket Gopher
Botta's Pocket Gopher
Tonwsend's Pocket Gopher
Kangaroo Rat Family - Heteromyidae
Ord's Kangaroo Rat
Chisel-toothed Kangaroo Rat
California Kangaroo Rat
New World Porcupines - Erethizontidae
American Porcupine
Nutria Family - Myocastoridae
Nutria - Myocastor Coypus
New World Rats and Mice - Cricetidae
Southern Red-backed Vole
Western Red-backed Vole
White-footed Vole
Red Tree Vole
Western Heather Vole
Meadow Vole
Water Vole
Montane Vole
Gray-tailed Vole
California Vole
Townsend's Vole
Long-tailed Vole
Creeping Vole
Sagebrush Vole
Western Jumping Mouse
Pacific Jumping Mouse
Western Harvest Mouse
Northwestern Deer Mouse
Deer Mouse
Canyon Mouse
Pinyon Mouse
Northern Grasshopper Mouse
Desert Woodrat
Dusky-footed Woodrat
Bushy-tailed Woodrat
Great Basin Pocket Mouse
Little Pocket Mouse
Dark Kangaroo Mouse
Old World Rats and Mice - Muridae
Norway Rat
Black Rat
Where to begin? From the list above, and quite possibly from your own experience, it is obvious that the Rodentia order of wildlife represents a teeming population around the world. Of the nearly 4,000 known species of mammals 42 percent are rodents. This same ratio holds true in the Northwest. Even if you count all the whales, dolphins, and porpoises that might inhabit our region, nearly half of all our mammals are rodents.
What makes a rodent a rodent? Opposing pairs of large incisors at the front of the upper and lower jaw are the most notable feature. Worn down through a lifetime of industrious gnawing the teeth grow throughout the animal's life, and are continuously sharpened as they rub against each other. For the most part the rodent brain is not large; the cranial case is small and elongated. The vast majority of them are small and they don't live a particularly long life. Their unremarkable bodies are fairly uniform throughout the order. Hovering at the bottom of the food chain they form the foundation of survival for many predators.
But you don't get to be the most numerous mammal on the planet without some secret to success. And the rodents have a couple. To begin with they are prolific breeders, the absolute champions among mammals. Take the average Harvest Mouse, for example. Sexually mature at five months she is capable of producing a litter of four pups every month. Even if she manages to live just a single year (the average for the species) she could potentially leave behind a progeny of over 50 harvest mice. Now consider that her children and her children's children are producing offspring at the same rate - well, you do the math.
The diminutive dimensions of most rodents is an advantage, too. Cover, camouflage, and food all favor the small. Predominately vegetarian and adapted to a wide variety of food the rodent does not require large territories or great quantities of forage. Many practice winter hibernation or summer aestivation, another advantage. Finally, man himself, with his penchant for open fields, farms, and trash has inadvertently created a rodent cornucopia.
The Northwest has an interesting rodent population. Our largest species are the Beaver and Porcupine. In the mid size range we have nutria (an introduced species), muskrats, woodchucks, gophers, marmots, squirrels, and chipmunks. Continuing down the size scale we have a wide variety of kangaroo rats, mice, and a generally little know group of rodents called voles. Voles, sometimes called meadow mice, can usually be weighed in ounces. They are small, extremely diverse in range and habitat, yet so similar that many can only be differentiated through close examination of the dentition or skull.
One of our more interesting rodents is the Mountain Beaver or Sewellel. Actually not a beaver at all, they resemble beavers only in the most superficial way, muskrat-like is probably a better description. A stout looking 3 pound animal, Aplodontia rufa is one of the most ancient rodents on earth. He is the only one of his kind in the world and found only along the western regions of British Columbia and south to the Sierra Nevada mountains in California. And despite their name Mountain beavers are not especially fond of high elevations and are found from sea level up to the tree line. Bracken fern, harmful to most animals are one of the Mountain Beaver's favorite foods.
Our real beaver, the American Beaver is our largest rodent. At weights approaching 70 pounds he is not only our largest, but also one of the largest in the world. The North American Porcupine fits into the giant rodent category, too. Coming in a 40 pounds, a portion of which is about 30,000 barb tipped quills, the porcupine is a formidable animal. (They are relatively easy to approach thanks to that pointy armor. Just be careful.)
As a family the voles are smallest rodents in our region, but the smallest of the small award goes to the Little Pocket Mouse - a quarter of an ounce in weight and just five inches from nose to tail.
Numerous though they are, rodents are elusive animals. You'll have more luck sighting a deer or elk than the quick and alert beaver. The little guys are so fast most people are aware of them only after a rustle of leaves or a sudden flash of movement. But any wildlife endeavor requires patience and timing - these are the keys. Porcupines tend to be most active at night. Beavers are lovers of the evening. Humane traps are the most effective way to investigate the smaller rodents. But if you decide to do this do not forget to check the trap frequently. Some of these little guys can suffer quickly without food or water for an extended period.
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