Bibliographical reference – how to cite this fact sheet: Nummi, P. (2010): NOBANIS – Invasive Alien Species Fact Sheet – Castor canadensis. – From: Online Database of the European Network on Invasive Alien Species – NOBANIS www.nobanis.org, Date of access

• Main Author: Castor Canadensis
• Other Authors: The Pennsylvania State University CiteSeerX Archives
• Format: Text
• Language: English
• Subjects: Arctic; Tundra
• Online Access: http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.606.1673; http://nobanis.slu.se/files/factsheets/Castor_canadensis.pdf

Species identification Castor canadensis is a large rodent with a flattened tail. Weight 16-32 kg, body length up to 120 cm (Jenkins and Busher 1979, Hill 1982). The external appearance of Castor canadensis is very similar to that of the European beaver (C. fiber L.), however, the nasal bones of C. canadensis are shorter and more rounded and its fur more brownish. The two species also differ in chromosome number: C. canadensis, 2N = 40; C. fiber, 2N = 48 (Lavrov 1983, Jenkins and Busher 1979). 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). Native range Castor canadensis occurs throughout North America except for the arctic tundra and southwestern deserts (Jenkins and Busher 1979). Alien distribution History of introduction and geographical spread Canadian beavers were introduced to Finland in 1937 as a part of the program to reintroduce the exterminated European beaver. The introductions were successful in eastern Finland where two