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Unformatted text preview: SNAKE-DIRECTED ANTIPREDATOR BEHAVIOR OF ROCK SQUIRRELS (SPERMOPHILUS VARIEGATUS): POPULATION DIFFERENCES AND SNAKE-SPECIES DISCRIMINATION by DONALD H. OWINGS 1) , RICHARD G. COSS 1,2) , DIANE MCKERNON 1) , MATTHEW P. ROWE 3) and PATRICIA C. ARROWOOD 4,5) ( 1 Department of Psychology, University of California, Davis, CA 95616-8686, USA; 3 Department of Biology, Appalachian State University, Boone, NC 28608, USA; 4 Department of Fishery and Wildlife Sciences, New Mexico State University, Las Cruces, NM 88003-8001, USA) (Acc. 23-II-2001) Summary The purposes of this study were: (1) to describe the snake-directed antipredator behavior of rock squirrels; (2) to assess whether rock squirrels distinguish nonvenomous gopher snakes from venomous rattlesnakes; (3) to compare antisnake behavior in a snake-rare urban site and a snake-abundant wilderness site as a means of assessing whether natural selection or experience has generated population differences in behavior; (4) to assess snake densities in the two study sites; (5) to compare the antisnake behavior of rock squirrels with that of their closest relatives, California ground squirrels ( Spermophilus beecheyi ), a species that appears 2) Corresponding author; e-mail address: [email protected] 5) This is Contribution No. 1 from the Arrowood Center for Research in Behavior and Biology. We thank the following individuals for facilitating the location of this research on the facilities that they administer: Mark Hakkila of the U.S. Bureau of Land Management’s Aguirre Spring Recreation Area; Prof. Bobby Rankin, Head of the Department of Animal and Range Sciences at New Mexico State University; and J.T. (Skip) Prichard, DVM. Roy Arrowood assisted us in a variety of ways. Prof. Carl Lieb, Associate Professor of Biological Sciences at the University of Texas at El Paso, and Paul W. Hyder assisted us in acquiring snakes for this study. The following individuals contributed to the quanti cation of video records: Andy Behrman, Amy Buchanan, Sonia Fong, Anne Fullerton, Sunnie Hong, Marnie Kagan, Joon Lee, Heather Mittelstaedt, Rod Santos, Marissa Schwartz, Yoka Sims, and Kate Traci. This research was supported by University of California Faculty Research Grants 80DHO2U and 80RGC2U to Owings and Coss, respectively, and an Appalachian State University Research Council Grant to Rowe. c ° Koninklijke Brill NV, Leiden, 2001 Behaviour 138, 575-595 576 OWINGS, COSS, MCKERNON, ROWE & ARROWOOD to differ from rock squirrels in exhibiting marked sexual-size dimorphism; and (6) to gather additional data on sexual size dimorphism in these two ground squirrel species. We tethered nonvenomous gopher snakes ( Pituophis melanoleucus ) and venomous western diamondback rattlesnakes ( Crotalus atrox ) in the eld near burrows of marked squirrels and videotaped the ensuing interactions. Rock squirrels from both urban and wilderness populations confronted snakes while waving their uffed tails from side to side, throwing substrate at the snakes, and...
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- Spring '08
- Snake, Ground Squirrel, Crotalus, California ground squirrel, Spermophilus, California ground squirrels