Castor canadensis (beaver)

Pictures

Picture	Title	Caption	Copyright
Title Adult Caption Castor canadensis (beaver, north American beaver); adult, in a rocky creek. The laterally flattened tail, or paddle, is clearly visible. Copyright ©Rodney Campbell-2011 - CC BY 2.0	Adult	Castor canadensis (beaver, north American beaver); adult, in a rocky creek. The laterally flattened tail, or paddle, is clearly visible.	©Rodney Campbell-2011 - CC BY 2.0
Title Yearling Caption Castor canadensis (beaver, north American beaver); yearling, grooming. The laterally flattened tail, or paddle, is clearly visible. Alhambra Creek, Martinez, California, USA. June, 2009. Copyright ©Cheryl Reynolds-2009 - CC BY-SA 3.0	Yearling	Castor canadensis (beaver, north American beaver); yearling, grooming. The laterally flattened tail, or paddle, is clearly visible. Alhambra Creek, Martinez, California, USA. June, 2009.	©Cheryl Reynolds-2009 - CC BY-SA 3.0
Title Adult Caption Castor canadensis (beaver, north American beaver); close view of an adult amongst riparian vegetation. Carburn Park, Calgary, Alberta, Canada. July, 2005 Copyright ©Chuck Szmurlo - CC BY-SA 3.0	Adult	Castor canadensis (beaver, north American beaver); close view of an adult amongst riparian vegetation. Carburn Park, Calgary, Alberta, Canada. July, 2005	©Chuck Szmurlo - CC BY-SA 3.0
Title Adult Caption Castor canadensis (beaver, north American beaver); adult swimming in the South Saskatchewan River. The laterally flattened tail, or paddle, is clearly visible. Saskatoon, Saskatchewan, Canada. August, 2009. Copyright ©SriMesh/wikimedia - CC BY-SA 3.0	Adult	Castor canadensis (beaver, north American beaver); adult swimming in the South Saskatchewan River. The laterally flattened tail, or paddle, is clearly visible. Saskatoon, Saskatchewan, Canada. August, 2009.	©SriMesh/wikimedia - CC BY-SA 3.0
Title Adult Caption Castor canadensis (beaver, north American beaver); adult gnawing tree in winter. Gatineau Park, Quebec, Canada. Copyright ©D. Gordon E. Robertson - CC BY-SA 3.0	Adult	Castor canadensis (beaver, north American beaver); adult gnawing tree in winter. Gatineau Park, Quebec, Canada.	©D. Gordon E. Robertson - CC BY-SA 3.0
Title Freshly felled tree Caption Castor canadensis (beaver, north American beaver); freshly felled 20cm diameter tree. Petrie Island Park, Ottawa, Ontario, Canada. November, 2010. Copyright ©D. Gordon E. Robertson - CC BY-SA 3.0	Freshly felled tree	Castor canadensis (beaver, north American beaver); freshly felled 20cm diameter tree. Petrie Island Park, Ottawa, Ontario, Canada. November, 2010.	©D. Gordon E. Robertson - CC BY-SA 3.0
Title Beaver damage Caption Castor canadensis (beaver, north American beaver); damage to the forest on the north shore of Robalo Lake, Navarino Island, Chile. January, 2005. Copyright ©James Cadwell - CC BY-SA 3.0	Beaver damage	Castor canadensis (beaver, north American beaver); damage to the forest on the north shore of Robalo Lake, Navarino Island, Chile. January, 2005.	©James Cadwell - CC BY-SA 3.0

Identity

Preferred Scientific Name

• Castor canadensis (Kuhl 1820)

Preferred Common Name

• beaver

International Common Names

• English: Canadian beaver; North American beaver; American beaver
• Spanish: castor americano

Summary of Invasiveness

Castor canadensis (beaver) is native to North America, and has been introduced to Tierra del Fuego in southern South America, Finland, France, Poland and Russia in recent times. In its introduced range, the damming activity of the beaver can cause flooding which can damage forests. They also have the ability to quickly cut down large numbers of trees. In Finland, they compete with native beaver populations. In their native range, they cause flooding on major highways by plugging highway culverts.

Taxonomic Tree

• Domain: Eukaryota
•     Kingdom: Metazoa
•         Phylum: Chordata
•             Subphylum: Vertebrata
•                 Class: Mammalia
•                     Order: Rodentia
•                         Family: Castoridae
•                             Genus: Castor
•                                 Species: Castor canadensis

Description

Castor canadensis (beaver) is a large hervbivorous rodent typically found near water. Adults may be up to 1200mm long and weigh between 18-47kg. Colour ranges from yellowish-brown to black with reddish-brown most common. Guard hairs are long and coarse and the under fur is dense and lead grey in colour. The tail is broad, scaly and dorsoventrally flattened. It is black in young animals but becomes lighter with age. Adaptations for aquatic life include nictitating membranes on the eyes, valvular ears and nose, lips closing behind incisors and webbed hind feet (Jenkins and Busher, 1979; Nummi, 2006).

Distribution

Native range: North America from northern Mexico to northern Canada.
Known introduced range: Finland, France, Poland, Russia, Argentine and Chilean Tierra del Fuego

Distribution Table

The distribution in this summary table is based on all the information available. When several references are cited, they may give conflicting information on the status. Further details may be available for individual references in the Distribution Table Details section which can be selected by going to Generate Report.

Habitat

Castor canadensis (beavers) are always found close to water and they require forest to provide food and building material (Nummi, 2006). Beavers have a unique ability to cut trees and this allows them to build mud and wood lodges in which they live, nest and store food. Lodges may be completely surrounded by water or built on the banks of ponds, lakes or streams.They are also able to build watertight dams which create ponds behind them where the beavers are then able to build lodges (Jenkins and Busher, 1979). This behaviour alters large areas of habitat and is the reason why beavers are termed “ecosystem engineers” (Nummi, 2006).

Habitat List

Biology and Ecology

Means of Movement and Dispersal

Introduction pathways to new locations
Landscape/fauna "improvement": Castor canadensis (beaver) was introduced to southern South American during an Argentine government program to establish furbearers in Tierra del Fuego.
Natural dispersal: Castor canadensis (beavers) have colonized adjacent islands dispersing themselves only by their own means.
Other: Castor canadensis (beaver) was introduced to Finland as part of a programme to reintroduce the European beaver (C. fiber). (Nummi, 2006). They were introduced to Poland and farmed (Nummi, 2006)

Local dispersal methods
Escape from confinement: Castor canadensis (beavers) have escaped from fur farms etc.

Pathway Causes

Impact Summary

Impact

General Impacts

Risk and Impact Factors

Impact mechanisms

• Herbivory/grazing/browsing
• Interaction with other invasive species

Impact outcomes

• Ecosystem change/ habitat alteration
• Increases vulnerability to invasions
• Modification of hydrology
• Modification of successional patterns
• Negatively impacts forestry
• Transportation disruption

Invasiveness

• Proved invasive outside its native range

Uses

Castor canadensis (beavers) are trapped and used primarily for their pelt (Langan, 1991). Beavers are being reintroduced to areas where they have been made extinct to improve wetland ecosystems.

Uses List

Materials

• Skins/leather/fur

Similarities to Other Species/Conditions

Castor fiber, the European Beaver, is smaller than Castor canadensis, the American Beaver. The European beaver weighs around 25kg, while the American Beaver weighs around 30-40kg (Streubel, 2000). C. fiber has a coat that varies from a glossy brown to a yellowish brown while C. canadensis has a reddish to blackish brown coat. The two species can also be identified from the secretions of their anal glands with which the animals scent mark the borders of their territories (Rosell and Sun 1999 in Nummi, 2006). C. canadensis out competed C. fiber in Finland because it uses resources better, has a greater number of offspring, and builds better dams (Nummi, 2000).

Prevention and Control

Management Information

Bibliography

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References

ISSG, 2011. Global Invasive Species Database (GISD). Invasive Species Specialist Group of the IUCN Species Survival Commission. http://www.issg.org/database

Principal Source

Global Invasive Species Database

Contributors

Principal sources: Christopher Anderson and Brett Maley, Institute of Ecology, University of Georgia, Athens GA 30605 and Omora Foundation, Puerto Williams, XII Region, Chile.
Nummi, P. 2006. NOBANIS – Invasive Alien Species Fact Sheet – Castor canadensis.
Jenkins, S.H. and Busher, P.E. 1979. Castor canadensis. Mammalian Species
Jenkins and Busher, 1979 and Nummi, 2006

Distribution Maps

• = Present, no further details
• = Evidence of pathogen
• = Widespread
• = Last reported
• = Localised
• = Presence unconfirmed
• = Confined and subject to quarantine
• = See regional map for distribution within the country
• = Occasional or few reports

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