Beavers are the largest rodents native to North America. Some may occasionally weigh 50 pounds (22.5 kg) or more. Beavers are primarily found along streams in areas with sufficient food, and where conditions are suitable for building a dam to form a pond. Although beavers were widespread in former times, there had been no evidence of their occurrence within the area now encompassed by the park until 1966 when beaver dams were discovered in a small branch of Eagle Creek within the park boundary (Park News and Views, 1966). Beavers are primarily nocturnal and are active during all seasons. Beavers feed primarily on the bark and outer layers of deciduous trees.

Species Measurements:
- Adult Total Length: 900-1,200 mm (36-60 in.)
- Tail: 225-300 mm (9-12 in.)
- Hind Foot: 150-163 mm (6-6? in.)
- Weight: 13.5-22 g (29-49 lbs.)

Physical Characteristics:
Beavers are the largest rodents native to North America. Some may occasionally weigh 50 pounds (22.5 kg) or more. The broad, flat, scaly tail is a key identification feature. Beavers are brown to blackish-brown with slightly paler underparts. The dense pelage consists of fine, short underfur overlaid with long, coarse, shiny guard hairs The ears are small and are set far back on the broad, rounded head. The flattened tail and webbed hind feet are black. Both the ears and the nose are equipped with valves that shut when the animal is underwater. The heavy, broad incisor teeth are dark orange-chestnut on their anterior surfaces.

Habitat:
Beavers are primarily found along streams in areas with sufficient food, and where conditions are suitable for building a dam to form a pond.

Reproduction:
Beavers usually mate for life and are monogamous. Females normally produce litters of three to four young with most kits being born during May and June. Gestation is approximately 107 days (Linzey, 1998). A kit at birth is about 375 mm long, has a flat tail 90 mm long, and weighs 0.2 to 0.6 kg. Kits are born with their eyes open, and are covered with soft fur. The incisor teeth of a newborn beaver are well developed, ready to erupt, and are covered with a thin layer of tissue.
The young mature slowly. In spite of the fact that they learn to swim at a month old and are weaned after six weeks, they remain under their parents' care for approximately two years. After which they either disperse voluntarily, or are forced to leave the lodge. Thus, a typical beaver colony may consist of the parents, kits, and yearlings.

Longevity:
The life span of beavers in the wild is approximately 10 to 12 years.

Terrestrial Ecology:
Beavers are primarily nocturnal and are active during all seasons. If their pond freezes over, they swim beneath the ice and feed on previously cached branches. Their home is in a lodge in the pond, or in a bank burrow. Lodges and burrows have underwater entrances that lead to dry chambers.

The senses of hearing, smelling, and touching are well developed. The sense of sight is not exceptional.

Feeding Behavior:
Beavers feed primarily on the bark and outer layers of deciduous trees such as birch (Betulaceae), willow (Salicaceae), Hazel alder (Alnus serrulata), Sweet gum (Liquidambar styraciflua), magnolia (Magnoliaceae), maple (Aceraceae), and dogwood (Cornaceae). They sometimes damage pine (Pinaceae). During the warmer months, they may supplement their diet with grasses, aquatic plants, and corn. Singer et al. (1981) found that beavers in the North Carolina section of the park showed the highest preference for black birch (Betula lenta) and dogwood (Cornaceae). The utilization rate was also high for yellow poplar (Liriodendron tulipifera), yellow birch (Betula alleghaniensis), oaks (Fagaceae), American sycamore (Platanus occidentalis), American hornbeam (Carpinus caroliniana), American beech (Fagus grandifolia), American witchhazel (Hamamelis virginiana), Eastern hemlock (Tsuga canadensis), and Hazel alder (Alnus serrulata).

Predators and Defense:
No predators recorded from the park.

Parasites:
No records from the park.

Beavers formerly ranged along streams and lakes throughout most of North America, from Alaska to Labrador and south to the Rio Grande. They have been extirpated over much of their former range primarily as a result of over trapping. However, the species has been successfully reintroduced in many places, and populations are increasing.

Although beavers were widespread in former times, there had been no evidence of their occurrence within the area now encompassed by the park until 1966 when beaver dams were discovered in a small branch of Eagle Creek within the park boundary (Park News and Views, 1966). A beaver was seen near the mouth of Pinnacle Creek on Eagle Creek April 7, 1968. Others were observed along the lower reaches of Hazel Creek (Park News and Views, 1968). Since 1968, beaver sightings, cuttings, and/or dams have been observed in Noland Creek, the Oconaluftee River, Deep Creek, and Fontana Lake. Singer et al. (1981) reported scattered beaver signs and one dam on the Tennessee side of the park at Metcalf Bottoms in 1970, Little River in 1975, Greenbrier in 1978, and Panther Creek in 1979. The first beaver sign in the park in this century was observed along Abrams Creek in Cades Cove January 18, 1990. The occurrence of beaver in the North Carolina portion of the park is probably the result of introductions made in western North Carolina by the North Carolina Wildlife Resources Commission.

Singer et al. (1981) stated: "In 1979, beaver occupied 31 km of five major drainages on the North Carolina side of Great Smoky Mountains National Park. Their reinvasion averaged 0.4 drainages and 2.4 km of waterway per year. Another 113 km of potentially habitable waterways exist for beaver, 17.4 in the North Carolina and 95.8 in the Tennessee portions of Great Smoky Mountains National Park. The major limitation for beaver range in the park is the steep gradients of the streams. Within the five occupied drainages, resident populations occur where the average percent slope of the stream is 2.2% (range 1.5 - 3.0, SD = 0.7), and transient use occurs where the average slope is 3.4% (range 3.1 - 40 [sic], SD = 0.4). Even in the range of 2%, the streams are too fast for dams, and except in occasional slow side tributaries, all beaver live in bank dens or burrows."

References:

Brimley, C. S. 1944-46. The Mammals of North Carolina. Eighteen Installments in Carolina Tips. Carolina Biological Supply Co., Elon College, NC.

Hamnett, W. L., and D.C. Thornton. 1953. Tar Heel Wildlife. North Carolina Wildlife Resource Commission. Raleigh, NC.

Jenkins, S. H. and P. E. Busher. 1979. Castor canadensis. Mammalian Species No. 120: 1-8. American Society of Mammalogists.

Linzey, A. V., and D. W. Linzey. 1971. Mammals of Great Smoky Mountains National Park. Knoxville: University of Tennessee Press.

Linzey, D. W. 1995a. Mammals of Great Smoky Mountains National Park. The McDonald & Woodward Publishing Company, Inc., Blacksburg, Virginia.

Linzey, D. W. 1995b. Mammals of Great Smoky Mountains National Park-1995 Update. Journal of the Elisha Mitchell Scientific Society 111(1): 1-81.

Linzey, D. W. 1998. The Mammals of Virginia. The McDonald & Woodward Publishing Company, Inc., Blacksburg, Virginia.

Rhoads, S. N. 1896. Contributions to the Zoology of Tennessee. No. 3: Mammals. Proceedings of the Philadelphia Academy of Natural Science 48: 175-205.

Singer, F. J., D. Labrode, and L. Sprague. 1981. Beaver Reoccupation and an Analysis of the Otter Niche in Great Smoky Mountains National Park. National Park Service, Southeast Regional Office Research/Resource Management Report no. 40.

Smith, D. W. 1999. American Beaver. Pages 548 - 552. In: D. E. Wilson, and S. Ruff (eds.). The Smithsonian Book of North American Mammals. Smithsonian Institution Press, Washington, D.C.