1. Order Rodentia Family Geomyidae
Diastema
1 pair incisors
Ears shorter than tail
External fur-lined pouches
Tail less than ¾ length of head, body
Hind feet smaller than forefeet
Geomys bursarius

2. Order Rodentia Family Heteromyidae
Diastema
1 pair incisors
Ears shorter than tail
External fur-lined pouches
Tail more than ¾ length of head, body
Hind feet larger than forefeet
Perognathus flavescens

3. Perognathus flavescens
Identification: Dorsum cinnamon with blackish hairs; venter lighter; light-colored patch behind ears and around eyes
Distribution: West (Loess Hills), southeast, central Iowa
Habitat: Grassy slopes; well drained; small burrows

4. Perognathus flavescens
Diet: Seeds of grasses, other herbs
Reproduction: 2-3 litters of 3-8 annually
Conservation: Endangered; several isolated populations

5. Order Rodentia Family Castoridae
Diastema
1 pair incisors
Ears shorter than tail
Hind feet webbed
Tail scaly, paddle-shaped
Castor canadensis

6. Castor canadensis Common name: Beaver
Order Rodentia
Family Castoridae
Genus Castor
Species Castor canadensis
Presented by Catherine Luria

7. Identification Largest rodent in Iowa
Castor canadensis
Identification
Largest rodent in Iowa
TL cm; tail, cm; hind foot, cm; ear, mm
Usually weighs kg, up to 45 kg

8. Castor canadensis
Distribution
Much of North America from central Alaska and Northern Canada to Northern Mexico
Found throughout Iowa and north-central United States

9. Habitat Streams, rivers, marshes, and lakes
Castor canadensis
Habitat
Streams, rivers, marshes, and lakes
Often near willow, aspen, and other preferred food sources

10. Castor canadensis
Diet
Summer: grasses, leaves, roots of aquatic plants, bark stripped from building materials, sometimes berries
Winter: leaves and inner bark of stored saplings and branches
Prefers willow, aspen,
cottonwood, alder; tends
to avoid pine except
for building
critters/beaver.asp

11. Castor canadensis
Diet
Stores food for winter by anchoring branches and saplings to bottom of pool
“Feed pile” is 3-6 feet deep and up to feet wide
Beaver leaves den through underwater entrance, gets food from the pile, and returns to the den
~sel/rideau/beaver.htm

12. Reproduction Breeding starts in January of February
Castor canadensis
Reproduction
Breeding starts in January of February
Female bears 1-6 kits (usually 3-4) in April, May, or June
Young are weaned
in 6 weeks but will
stay with family
group 1-2 years

13. Reproduction Family groups consist of around 12 beavers
Castor canadensis
Reproduction
Family groups consist of around 12 beavers
One or more pairs of adults
Young of that year
Yearlings
Yearlings leave or
are driven off as
kits mature

14. Conservation Status Valuable pelt
Castor canadensis
Conservation Status
Valuable pelt
Once trapped to extinction in some areas
Protective legislation and natural emigration have allowed beaver to reoccupy much of its former range
Now fairly common, even considered a pest in some areas

15. Disease Can carry rabies Carries tularemaia Bacterial infection
Castor canadensis
Disease
Can carry rabies
Carries tularemaia
Bacterial infection
Transmitted to humans through contact with beaver tissue or blood or through contaminated water
Causes headache, fever, chills, vomiting, aches and pains

16. Castor canadensis
Dam building
Dams constructed of branches, rocks, leaves, and other debris and filled with mud from the stream bottom
4-7 feet across
Added to as water level rises
Smaller dams are sometimes constructed to relieve pressure on main dam

17. Why do beavers build dams?
Castor canadensis
Why do beavers build dams?
Increases the depth and surface area of the stream or pond
Easier to drag branches, etc.
Prevents the underwater entrance to the den or lodge from freezing over
Protects against predation
Allows greater access to food

18. Castor canadensis
Beaver Lodges
Built against the back of the den or against the stream bank
Dome-like structure built of sticks and mud
Underwater entrance(s)

19. Other Primarily nocturnal/crepuscular
Castor canadensis
Other
Primarily nocturnal/crepuscular
Presence easily detected by chewed saplings
Little predation: mink take young and large carnivores may attack adults

20. References
Illinois Department of Natural Resources. Ecology and Conservation of Illinois’ Fur Resources.
Iowa Association of Naturalists. Iowa Mammals.
Jones, J. Knox, Jr. and Elmer C. Birney Handbook of Mammals of the North-Central States. University of Minnesota Press, Minneapolis.
Kays, Roland W. and Don E. Wilson Mammals of North America. Princeton University Press, Princeton, NJ.