Exploratory Behavior in Prairie Rattlesnakes ( Crotalus Viridis ) and Water Moccasins ( Agkistrodon Piscivorus )

Six prairie rattlesnakes (Crotalus viridis) and six water moccasins (Agkistrodon piscivorus) were observed for 10 min. under each of four conditions: (a) home cage after brief handling, (b) a cage formerly occupied by a hognose snake (Heterodon nasicus; harmless to both rattlesnakes and moccasins), (c) a cage formerly occupied by a kingsnake (Lampropeltis getulus; a predator of both rattlesnakes and moccasins), and (d) a clean open field. The latter three conditions were novel environments for the subjects. The dependent variable was the number of tongue flicks emitted per min. Tongue-flick rates were greatest in the open field and hognose snake cage and lowest in the home cage, indicating that more tongue flicking occurs in the harmless novel environments than can be explained solely on the basis of handling. This difference provides an operational definition of exploratory behavior. The kingsnake cage generated a rate of tongue flicking which was higher than that seen in the home cage but lower than the rates seen in the open field and hognose snake cage, indicating that odors of this predator inhibit exploration by potential prey. The inhibitory effect was stronger in water moccasins than in rattlesnakes.