Olfactory Snake‐Predator Discrimination in the Cape Ground Squirrel

Abstract

Small mammals have a number of means to detect and avoid predators, including visual, auditory and olfactory cues. Olfactory cues are particularly 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.

An ambusher's arsenal: chemical crypsis in the puff adder (Bitis arietans)

“…This finding suggests that scent collected from shed skin may not always serve as a suitable proxy for the body odour of snakes, and we caution against making this assumption in experiments (e.g. [47]). However, the high detectability of shed skins is particularly relevant in the context of two important field observations of telemetered free-ranging puff adders: puff adders always moved to new lie-up positions following shedding; puff adders typically defecated at the site of shedding before moving.…”

Both familiarity and kinship influence odour discrimination by females in a highly social African ground squirrel

“…For each odour trial, we used an unscented cube as a control. After use, the cubes (and tarps, see below) were soaked for five minutes in a 50% vinegar solution, rinsed with water, and dried by sunlight before being used again (Phillips & Waterman 2013;Shave & Waterman 2017).…”

“…We observed for 30 minutes oruntil the focal squirrel left the cubes for longer than 5 minutes. We also recorded wind and weather conditions to ensure that wind did not affect squirrel behaviour or odour dispersal; trials were not run if wind speeds were higher than 18.0 km/h(Phillips & Waterman 2013;Shave & Waterman 2017).…”