Effect of Downed Woody Debris on Small Mammal Anti-Predator Behavior

The threat of predation is often the largest cost associated with foraging (Brown & Kotler 2004; Preisser et al. 2005; Creel & Christianson 2008). Foragers primarily assess the threat of predation based on indirect cues of risk, such as microhabitat features and environmental conditions (Orrock et al. 2004; Verdolin 2006). For example, small mammals often respond to the threat of predation by biasing their foraging activity to areas of shrub cover and by increasing foraging on rainy, overcast nights (Brown & Kotler 2004; Verdolin 2006). Although it is well known that small mammals lower the cost of predation by altering their behavior in response to shrubs (e.g., Brown & Kotler 2004; Orrock et al. 2004; Mattos & Orrock 2010), much less is known about how other microhabitat features (e.g., rocks and downed woody debris) alter the anti-predator behavior of small mammals in the field (but see Wywialowski 1987 for a lab-based study of habitat structure). Understanding how microhabitat features affect antipredator behavior is important not only for understanding one of the primary costs for foraging small mammals, but also because forest management practices can have significant effects on the composition of microhabitat features. Downed woody debris is an important microhabitat feature for numerous species of terrestrial animals, including small mammals (Loeb 1996). Small mammals use cavities in downed woody debris as daytime refuges (McCay 2000; Hinkelman & Loeb 2007) and the surface of downed woody debris as travel routes (Barnum et al. 1992; Planz & Kirkland Correspondence Travis M. Hinkelman, School of Biological Sciences, University of Nebraska, Lincoln, NE 68588, USA. E-mail: [email protected]