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This article provides information on three orders of rodents found in Iowa: Geomyidae, Heteromyidae, and Castoridae. It covers their identification, distribution, habitat, diet, reproduction, conservation status, and other interesting facts.
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Order RodentiaFamily 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 RodentiaFamily 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; light-colored 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 3-8 annually Conservation: Endangered; several isolated populations
Order RodentiaFamily Castoridae • Diastema • 1 pair incisors • Ears shorter than tail • Hind feet webbed • Tail scaly, paddle-shaped Castor canadensis
Castor canadensisCommon 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/www/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/www/schoolhouse/boreal_library/animals/photos/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 main dam http://www.exzooberance.com/virtual%20zoo/they%20swim/beaver/Beaver%20485050.jpg
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 http://www.bfro.net/avevid/nelson/images/beaver%20dam.jpg
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.
