RESEARCH PAPER Olfactory Snake-Predator Discrimination in the Cape Ground Squirrel Molly A. Phillips & Jane M. Waterman Department of Biological Sciences, University of Manitoba, Winnipeg, MB, Canada Correspondence Jane M. Waterman, Department of Biological Sciences, University of Manitoba, Winnipeg, MB R3T 2N2 Canada. E-mail: jane.waterman@ad.umanitoba.ca Received: September 6, 2012 Initial acceptance: October 4, 2012 Final acceptance: January 2, 2013 (L. Ebensperger) doi: 10.1111/eth.12059 Abstract Small mammals have a number of means to detect and avoid predators, including visual, auditory and olfactory cues. Olfactory cues are particu- larly important for nocturnal or fossorial species where visual cues would not be as reliable. The Cape ground squirrel (Xerus inauris) is a semi- fossorial, diurnal mammal from southern Africa. Cape ground squirrels encounter multiple species of predatory snake that pursue individuals underground where visual and social cues are limited. We assessed whether Cape ground squirrels use odours to discriminate between snakes by presenting a non-venomous snake, a venomous snake and a control odour collected on polyethylene cubes to 11 adult female squirrels from 11 different social groups. Cape ground squirrels responded by inspecting the cube, displaying snake harassment–associated behaviours and decreasing time spent in close proximity to snake odours when compared with a control. They also displayed discrimination between two snake species by increasing the frequency of cube inspection and increasing harassment behaviours with venomous snake odours when compared with non-venomous snake odours. We conclude that Cape ground squirrels respond with snake-specific antipredator behaviours when presented olfactory cues alone. Olfactory discrimination may be maintained by the decreased utility of other methods of predator detection: sight and group detection, in below-ground encounters. Prey species use a variety of senses to recognize preda- tors (Apfelbach et al. 2005). Visual cues are especially important for predator detection by species living in open habitats (Mitchell & Skinner 2003). Auditory signals, especially alarm calls produced by other potential prey individuals, are also important for social species that cannot always rely on vision (Warkentin et al. 2001). Olfactory cues (particularly predator odour) are another major signal, especially in prey species that are nocturnal or otherwise visu- ally limited (like many fossorial mammals) (Apfelbach et al. 2005). A number of studies have demonstrated that many species are capable of identifying predators by their odour, including several species of ungulates and rodents (reviewed in Apfelbach et al. 2005). The majority of research examining responses to predator chemical cues has focused on how prey alter their activity patterns (Borowski 1998; Perrot-Sinal et al. 1999; Borowski & Owadowska 2001) and shift habitat (Dickman 1992; Ward & Macdonald 1997) in the pres- ence of predator odours. Some prey species are able to discriminate between specific predator odour cues and modify their behaviour to match the perceived risk (Blumstein et al. 2008). The mountain log skink (Pseudemoia entrecasteauxii) discriminates between snake-predators, avoiding refuges tainted with snake odours from their most common snake-predator and choosing refuges tainted with the odour of less com- mon predatory snakes (Stapley 2003). A freshwater snail (Physella heterostropha pomila) also exhibits increased avoidance behaviours as predator risk increases (McCarthy & Fisher 2000). The Cape ground squirrel (Xerus inauris) is a highly social, diurnal, semi-fossorial sciurid from southern Africa (Waterman 1995; Skurski & Waterman 2005). Cape ground squirrels live in open habitats and use both visual and auditory cues to detect predators Ethology 119 (2013) 278–285 © 2013 Blackwell Verlag GmbH 278 Ethology