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Tent or bunker: Woody debris facilitates lability in refuge selection behavior by cotton mice.
Hinkelman, Travis*,1, Loeb, Susan2, Allen, Craig 1, 1 Clemson University, Clemson, South Carolina2 USDA Forest Service, Clemson, South Carolina
ABSTRACT- Daytime refugia are important to nocturnal rodents for protection from predators and environmental extremes. High refuge fidelity, however, increases the probability of parasite infestation and detection by predators. Behavioral plasticity in refuge selection mitigates the effects of parasites and predators as well as lowering risks associated with refuge destruction while allowing animals to maintain proximity to spatially and temporally variable food resources. Since the daytime refugia of cotton mice (Peromyscus gossypinus) are highly associated with woody debris, we expected mice in areas with large amounts of woody debris to use more refuges and a greater diversity of refuge types than mice in areas with low levels of woody debris. The study was conducted as part of a large-scale field experiment on the Savannah River Site (SRS) where treatment plots contained six times the amount of woody debris as control plots. We used radiotelemetry to identify refuges within this treatment structure during two periods: May-July 2002 and February-July 2003. We classified refuges by use-intensity and used polytomous logistic regression (PLR) to model use-intensity as a function of sex, season, treatment, and refuge type. We failed to detect a relationship between use-intensity and sex, season, or treatment, but refuge type was a significant predictor of use-intensity. Cotton mice used debris refuges less intensely than other refuge types. Further, individuals on treatment plots used a greater diversity of refuge types than mice on control plots. Although treatment was not a significant indicator of use-intensity, mice on treatment plots tended to use each refuge less frequently than mice on control plots. The input of woody debris provides additional refuge sites that are suitable for limited use and confers the advantages inherent in refuge switching behavior.
Key words: woody debris, refuge selection, Peromyscus gossypinus