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© Patrick Dockens
Castor canadensis - Canadian beaver

French name:  Castor canadien
Dutch name: Canadese bever
Family: Castoridae
Group: Mammals
Origin: North America
Habitat: freshwater
Introduction:  fur farming
ISEIA Score : 10
Naturalization in Belgium
First observation in the wild: 2009
Invasion stage: naturalization
Spatial distribution: isolated
Reproduction in the wild: yes
Dispersion potential: high
Natural habitats: high
More on invasiveness: As for the European beaver, the Canadian beaver lives in riparian zones, rivers and lakes, usually included in a forest matrix providing food and building material. Lodges may be completely surrounded by water or built on the banks of streams and lakes. It has a greater ecological flexibility, survives better under severe climatic conditions and adapt more easily to substitute foods than its Eurasian counterpart.
Distribution in Belgium
Established populations
absent from district
isolated populations (1-5 localities per district)
widespread (>5 localities per district)

Impacts on Species
Predation / Herbivory: medium
Competition: likely
Disease transmission: unknown
Genetic effects: low
Impacts on Ecosystems
Nutrient cycling: medium
Physical alteration: medium
Natural successions: medium
Food web alteration: medium
More on impacts: Castor canadensis is likely to outcompete the native Castor fiber due to higher reproductive output. It is a more active builder of dams and lodges than C. fiber and regulates hydrological regimes of water bodies better than C. fiber, leading to a slightly higher impact on ecosystems. The two species do not hybridise due to a difference in chromosome numbers.
Data Source & References
Authors: Branquart Etienne, Licoppe Alain, Motte Grégory, Schockert Vinciane, Stuyck Jan
Published on:  23 March 2009
Last update:  22 July 2022
Danilov, P. (1995)
Canadian and European beavers in Russian northwest.
Proceedings of the third Nordic beaver symposium, Finnish Game and Fisheries Institute, pp. 10-16.
Danilov, P.I. & Kan'shiev, V.Y. (1983)
The state of populations and ecological characteristics of European (Castor fiber L.) and Canadian (Castor canadensis K.) beavers in the northwestern USSR.
Acta Zoologica Fennica 174: 95-97.
Dewas, M., Herr, J., Schley, L., Angst, C., Manet, B., Landry, P. & Catusse, M. (2011)
Recovery and status of native and introduced beavers Castor fiber and Castor canadensis in France and neighbouring countries.
Mammal Review
Halley, D.J. & Rosell, F. (2002)
The beaver's reconquest of Eurasia: status, population development and management of a conservation success.
Mammal Review 32(3): 153-178.
Hollander, H., van Duinen, G.A., Branquart, E., de Hoop, L, de Hullu, P.C., Matthews, J., van der Velde;, G. & Leuven, R.S.E.W. (2017)
Risk assessment of the alien North American beaver (Castor canadensis).
Reports Environmental Science 528, Dpt Environmental Science, Radboud University.
Hollander, HD, van Duinen, GA, Branquart, E, Hoop, L D, De Hullu, PC, Matthews, J, van der Velde, G & Leuven, RSEW (2017)
Risk assessment of the alien North American beaver (Castor canadensis).
Netherlands Centre of Expertise for Exotic Species (NEC-E), Bargerveen Foundation, Dutch Mammal Society, Service Public de Wallonie and Radboud University (Institute for Water and Wetland Research, Department of Environmental Science).
ISSG (Invasive Species Specialist Group) (2006)
Online fact sheets
Global Invasive Species Database, IUCN.
Nolet, B.A. & Rosell, F. (1998)
Comeback of the beaver Castor fiber: an overview of old and new conservation problems.
Biological Conservation 83: 165-173.
Nummi, P. (2007)
Invasive Alien Species fact sheet, Castor canadensis.
From online database of the North European and Baltic network on invasive alien species (NOBANIS).
Rosell, F. & Sun, L. (1999)
Use of anal gland secretion to distinguish the two beaver species Castor canadensis and C. fiber.
Wildl. Biol. 5: 119-123.
Rosell, F., Bozser, O., Collen, P. & Parker, H. (2005)
Ecological impact of beavers Castor fiber and Castor canadensis and their ability to modify ecosystems.
Mammal Rev. 35 (3-4): 248–276.

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