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Argos DCS System Use Agreement of the Month
– January 2017

Spatial Ecology of Barred Owls & Spotted Owls
University of Wisconsin – Department of Forest & Wildlife Ecology


Barred owls have colonized much of the Pacific Northwest, resulting in substantial declines in the abundance and distribution of the endangered northern spotted owl. Currently, barred owls are relatively rare in the Sierra Nevada, the core range of the declining California spotted owl (CSO). However, increases in barred owl abundance in the Sierra Nevada could accelerate CSO declines. Our research is designed in part to understand the spatial ecology of the nascent barred owl expansion in the Sierra Nevada in order to guide management of both the barred owl and the CSO.


1)  track dispersing juvenile barred owls to determine dispersal capabilities and locate previously unknown aggregations of adult barred owls over larger spatial scales than might be possible with surveys;
2)  track adult and sub-adult barred owls during the breeding season to determine whether they are maintaining distinct territories; and
3)  track adult and sub-adult California spotted owls during the breeding season to determine how the presence of barred owls may influence the spatial ecology of the spotted owl.

Potential Results:

1)  We expect juvenile dispersal to be characterized by periods of rapid, long-distance movements punctuated by periods of relative stasis. This pattern would likely be driven by the tension between an intrinsic behavioral disposition towards dispersal and the recognition of patches of high-quality habitat. Dispersal distances may be low, because there are likely relatively few territorial adult conspecifics preventing them from establishing territories, or they could be high because the birds may move until a suitable mate is found.
2)  If barred owls exist at low densities in the Sierra Nevada, we expect that they will not consistently maintain and defend static territories, and will instead move widely across the landscape in search of a mate.
3)  It is widely accepted that barred owls out-compete spotted owls. However, there is very little detailed spatial information regarding how those interactions unfold. Competition may cause home range size to decrease, as individuals are prevented from accessing more distant resources.

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