24 February 2011 Science Briefs

SNAMP Publication #3: Do California spotted owls select nest trees close to forest edges?

Casey E. Phillips, Douglas J. Tempel, and R. J. GutiƩrrez

    We tested the hypothesis that California spotted owls nest closer to (or further from) forest edges than expected by chance. Spotted owls might nest closer to edges if they prefer to forage in younger forests near their nest stand. Conversely, spotted owls may prefer the interior of a nest stand for a number of reasons (e.g., cooler microclimate, protection from predators). Finally, spotted owls may choose nest sites wherever they occur (irrespective of the distance to the nearest edge) if nest stands contain a limited number of suitable nest trees. We defined two types of edge: 1) a low-contrast edge between a nest stand and other forest types containing potential nesting habitat, and 2) a high-contrast edge between a nest stand and forest or vegetation types that are not used for nesting. Using data collected on the Eldorado Study Area from 1986-2009, we compared 49 nest locations to random locations within the same nest stands. We found no evidence that spotted owls selected nest sites closer to an edge than random locations. In fact, owls appeared to select nest sites that were further from high-contrast edges.

    Full Reference: Phillips, C.E., D.J. Tempel, and R.J. Gutierrez. 2010. Do California spotted owls select nest trees close to forest edges? Journal of Raptor Research 44:311-314.

    The full paper is available at: http://fwcb.cfans.umn.edu/research/owls/publications/current.html

    For more information about the SNAMP project and the Owl team, please see: http://snamp.cnr.berkeley.edu/teams/owl

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