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Copyright © 2006 by the author(s). Published here under license by The Resilience Alliance.
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The following is the established format for referencing this article:
Harron, D. E. 2006. Response to: ‘Should ecosystem management involve active control of species abundances?’. Ecology and Society 11(1): r1. [online] URL: http://www.ecologyandsociety.org/vol11/iss1/resp1/


Response to Lessard et al. 2005. “Should Ecosystem Management Involve Active Control of Species Abundances?

Response to: ‘Should Ecosystem Management Involve Active Control of Species Abundances?’

Don E. Harron



Key words: model; moose; predation; wolves; woodland caribou.


Lessard et al. (2005) errors in “Case 2: Large mammal interactions in northern boreal forest” when assuming that “caribou are more vulnerable to predation than moose”. James et al. (2004), in a study of northern Alberta woodland caribou, notes that “caribou were not killed in proportion to their availability” and found that individual woodland caribou were approximately one-tenth as likely to be subject to predation compared to individual moose, supporting the Hayes et al. (2000) observation that “wolves did not show a strong switching response away from moose as the ratio of caribou to moose increased in winter”. The assumption of increased predation risk is contrary to the literature and results in an order of magnitude error being introduced into the model results.

The Case 2 scenario also assumes that both moose and woodland caribou initial population densities are the same at about 0.15 per km2. While moose densities can occur at the stated levels, Thomas and Gray (2002) note that typical woodland caribou densities are between 0.01 to 0.03 per km2, or an order of magnitude lower. This introduces another order of magnitude error into the analysis.

It is likely that the Case 2 model over estimates the linkage between moose, woodland caribou, and wolf population ecology by at least two orders of magnitude and the study conclusions should be rejected.


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LITERATURE CITED


Hayes, R., A. Baer, U. Wotschikowsky, and S. Harestad. 2000. Kill rate by wolves on moose in the Yukon. Canadian Journal of Zoology 78:49-59.

James, A., S. Boutin, D. Hebert, and A. Rippin. 2004. Spatial separation of caribou from moose and its relation to predation by wolves. Journal of Wildlife Management 68(4):799-809.

Lessard, R., S. Martell, C. Walters, T. Essington, and J. Ketchell. 2005. Should ecosystem management involve active control of species abundances? Ecology and Society 10(2):1. [Online.] URL: http://www.ecologyandsociety.org/vol10/iss2/art1/.

Thomas, D.C., and D.R. Gray. 2002. COSEWIC Assessment and Update Status Report on the Woodland Caribou, Rangifer tarandus caribou, in Canada. Pages 1-98 in COSEWIC Committee on the Status of Endangered Wildlife in Canada. Environment Canada, Ottawa, Ontario, Canada.



RESPONSES TO THIS ARTICLE


Responses to this article are invited. If accepted for publication, your response will be hyperlinked to the article. To submit a response, follow this link. To read responses already accepted, follow this link



LITERATURE CITED


Hayes, R., A. Baer, U. Wotschikowsky, and S. Harestad. 2000. Kill rate by wolves on moose in the Yukon. Canadian Journal of Zoology 78:49-59.

James, A., S. Boutin, D. Hebert, and A. Rippin. 2004. Spatial separation of caribou from moose and its relation to predation by wolves. Journal of Wildlife Management 68(4):799-809.

Lessard, R., S. Martell, C. Walters, T. Essington, and J. Ketchell. 2005. Should ecosystem management involve active control of species abundances? Ecology and Society 10(2):1. [Online.] URL: http://www.ecologyandsociety.org/vol10/iss2/art1/.

Thomas, D.C., and D.R. Gray. 2002. COSEWIC Assessment and Update Status Report on the Woodland Caribou, Rangifer tarandus caribou, in Canada. Pages 1-98 in COSEWIC Committee on the Status of Endangered Wildlife in Canada. Environment Canada, Ottawa, Ontario, Canada.


Address of Correspondent:
Don E. Harron
Box 195
Starbuck, Manitoba, Canada
R0G 2P0
dharron@skyweb.ca

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