Download Castor canadensis - Natural Resource Ecology and Management

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
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
Perognathus flavescens
Identification: Dorsum
cinnamon with blackish
hairs; venter lighter; lightcolored patch behind ears
and around eyes
Distribution: West (Loess
Hills), southeast, central
Iowa
Habitat: Grassy slopes; well
drained; small burrows
Perognathus flavescens
Diet: Seeds of grasses, other
herbs
Reproduction: 2-3 litters of 38 annually
Conservation: Endangered;
several isolated populations
Order Rodentia
Family Castoridae
•
•
•
•
•
Diastema
1 pair incisors
Ears shorter than tail
Hind feet webbed
Tail scaly, paddleshaped
Castor canadensis
Castor canadensis
Common name: Beaver
• Order Rodentia
– Family Castoridae
• Genus Castor
–Species Castor canadensis
http://www.inhs.uiuc.edu/dnr/fur/species/beaver.html
Presented by Catherine Luria
Castor canadensis
Identification
• Largest rodent in Iowa
• TL 94-120 cm; tail, 23-37
cm; hind foot, 17-19 cm;
ear, 30-35 mm
• Usually weighs 15-30 kg, up to 45
kg
http://www.inhs.uiuc.edu/dnr/fur/species/beaver.html
Castor canadensis
Distribution
• Much of North America from central
Alaska and Northern Canada to Northern
Mexico
• Found throughout Iowa and north-central
United States
http://www.huntington.edu/thornhill/images/wildlifephotos/beaver.jpg
Castor canadensis
Habitat
• Streams, rivers, marshes, and lakes
• Often near willow, aspen, and other
preferred food sources
http://www.huntington.edu/thornhill/images/wildlifephotos/beaver.jpg
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
www.wildflorida.org/ critters/beaver.asp
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 30-40 feet wide
• Beaver leaves den through
underwater entrance, gets
food from the pile, and
returns to the den
www.occdsb.on.ca/ ~sel/rideau/beaver.htm
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
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
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
http://www.wildernessclassroom.com/w
ww/schoolhouse/boreal_library/animals
/photos/beaver.jpg
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
http://www.wildernessclassroom.com/ww
w/schoolhouse/boreal_library/animals/pho
tos/beaver.jpg
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
http://www.exzooberance.com/virtual%20zoo/they%20s
main dam
wim/beaver/Beaver%20485050.jpg
Castor canadensis
Why do beavers build dams?
• Increases the depth
and surface area of
the stream or pond
http://www.bfro.net/avevid/nelson/images/beaver%20dam.jpg
– 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
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)
http://www.saskschools.ca/~gregory/animals/images/bvr2.jpg
Castor canadensis
Other
• Primarily nocturnal/crepuscular
• Presence easily detected by chewed saplings
• Little predation: mink take young and large
carnivores may attack adults
References
Illinois Department of Natural Resources. Ecology and Conservation of
Illinois’ Fur Resources. http://www.inhs.uiuc.edu/dnr/fur/index.html
Iowa Association of Naturalists. Iowa Mammals.
http://www.extension.iastate.edu/publications/ian601.pdf
Jones, J. Knox, Jr. and Elmer C. Birney. 1988. Handbook of Mammals of
the North-Central States. University of Minnesota Press, Minneapolis.
Kays, Roland W. and Don E. Wilson. 2002. Mammals of North America.
Princeton University Press, Princeton, NJ.