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Rodent Facts
Rodents are small mammals [except for South American
capybara which is about 4 feet (1.25 meters) long] belonging to the order
Rodentia. Most of them weigh less than 100g (3.5 Oz). Mostrodents
are squat, compact mammals with short limbs and a tail. They can
be distinguished from other mammals by: (1) a pair of chisel-likefront teeth,
called incisors, (2) lack of canine teeth, (3) a few molarson each side of
the jaw, and (4) a toothless gap between the incisorsand cheek teeth.
The incisors continue to grow during the life time,but are worn down by gnawing
(the name rodent comes from the Latin wordrodere, which means “to gnaw”).
Rodents are quite intelligentand can master simple tasks when conditioned.
They have an acutesense of hearing, smell, taste and touch. Rodents
are highly socialanimals and use many of their senses to communicate.
Their behavioris highly adaptable. Rodents have high rate of
reproduction. Most species commonly have 6-12 young in each litter and
a female can haveone litter each month (gestation period for rats is 21 to
23 days). Breeding occurs mostly in spring and fall. In
most speciesfemale can reach maturity at two to five months of age (about
three monthsin rats). Because of their high reproductive rates and
ability toinvade many habitats, rodents are able to spread and multiply
quickly. Population, however, may soon crash because of predation, disease
and foodshortages.
There are 1702 known species of rodents including
beavers,chipmunks, guinea pigs, hamsters, mice, porcupines, rats, squirrels
andvoles (Table 1). The largest
rodent family is Muridae (rats and mice). It containsabout
1,011 species, i.e. about 2/3 of all rodent species. The secondmost
numerous family is Sciuridae (squirrels). Archaeological
record shows that rodents were present even 58 million yearsago. These
animals, however, diversified into leaping, running andburrowing forms between
54 and 38 million years ago.
Most rodents eat a wide range of plant material
as wellas invertebrates. A few are specialized carnivores. Most
rodentshave a little contact with humans. Nevertheless, some species
likerats and mice are pests in houses, agricultural crops, and food storage.
Rodent pests can transmit more than 20 pathogens to humans. The bubonicplague
was responsible for the death of 25 million people just in Europein the 14-17th
centuries. The three main rodent pests to human are thecommon rat, roof rat,
and the house mouse. Rodent may kill plantcrops, or eat/contaminate
stored food. Each year rodents damageagricultural crops and produce
worth of an estimated 30 billion U.S. dollars. Rodents are an important
part of the diet of many carnivorous mammals andbirds. Only a few species
are hunted and eaten by humans.
Taxonomy
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Order:
Rodentia
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Suborders: 3
Families: 30
Genera: 389
Species: 1702
Some important Families with Examples
Family:
Capromyidae
Nutria (Myocastor coypus)
Family: Castoridae
Beaver (Castor canadensis
)
Family: Cricetidae
Deer Mouse (Peromyscus maniculatus
)
White-Footed Mouse (Peromyscus
leucopus)
Meadow Vole (Microtus pennsylvanicus
)
Prairie Vole (Microtus ochrogaster
)
Woodland Vole (Microtus pinetorum
)
Family: Erethizontidae
Porcupine (Erethizon dorsatum
) |
Family:Muridae
Common Rat (Rattus norvegicus
)
Black Rat (Rattus rattus)
House Mouse (Mus musculus
)
Family: Sciuridae
Eastern Chipmunk (Tamias striatus
)
Groundhog (Marmota monax)
Fox Squirrel (Sciurus nige
r)
Red Squirrel (Tamiascurius hudsonicus
)
Family: Zapodidae
Meadow Jumping Mouse (Zapus hudsonius
)
Woodland Jumping Mouse (Napaeozapus
insignis |
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