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Copyright © 2007 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. 2007. Assumptive error and overestimation of effects in wildlife model output. Ecology and Society 12(1): r3. [online] URL: http://www.ecologyandsociety.org/vol12/iss1/resp3/

Response to Schneider et al. 2003. “Managing the Cumulative Impacts of Land Uses in the Western Canadian Sedimentary Basin: A Modeling Approach.

Assumptive Error and Overestimation of Effects in Wildlife Model Output

Donald E. Harron

Key words: avoidance; seismic line; wildlife model; woodland caribou,

Schneider et al. (2003) make an assumptive error that limits the degree to which the model results should be considered as representative of ecosystem function.

The key assumptive error involves the woodland caribou “avoidance distance...100 m for seismic lines” attributed to Dyer et al. (2001). The term “avoidance” suggests a 100% reduction in use by woodland caribou. This is inconsistent with the results of Dyer (1999) that found statistically significant reduction in use by woodland caribou of between 25% and 52%, i.e., an average annual of 40%, of areas within 100 m of a seismic line. Woodland caribou do not avoid using areas within 100 m of seismic lines, but there is a reduction in the use of these areas, resulting in a loss of about 40 m of effective habitat equivalent on either side of the line. The model therefore overestimates the influence of seismic lines on woodland caribou habitat by about 250% above literature values.

Figure 1 explores this assumptive error using a simple spreadsheet model. Based on historical seismic lines and future projection provided in Schneider et al. (2003), and end of the effect after 40 yr of seismic line vegetative regeneration, there is a substantive change to the potential effects on habitat. Woodland Caribou in southern Manitoba begin to use coniferous dominated 30-50-yr-old cutblocks and wildfire burns at approximately the same rate as random points. Predicted effects of seismic lines on habitat availability are substantively reduced.


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Dyer, S. J. 1999. Movement and distribution of woodland caribou (Rangifer tarandus Caribou) in response to industrial development in northeastern Alberta. Thesis. University of Alberta, Edmonton, Alberta, Canada.

Dyer, S. J., J. P. O'Neill, S. M. Wasel, and S. Boutin. 2001. Avoidance of industrial development by woodland caribou. Journal of Wildlife Management 65:531-542.

Schneider, R. R., J. B. Stelfox, S. Boutin, and S. Wasel. 2003. Managing the cumulative impacts of land uses in the Western Canadian Sedimentary Basin: a modeling approach. Conservation Ecology 7(1):8. [online] URL: http://www.consecol.org/vol7/iss1/art8/

Address of Correspondent:
Donald E. Harron
Box 195
Starbuck, Manitoba
R0G 2P0

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