The Herpetological Journal

pp. 199-203
Authors: Smith, Geoffrey R.; Burgett, Amber A.; Sparks, Kathryn A.; Temple, Kathleen G. & Winter, Kristen E.

Abstract: The presence of predators or predator cues has an effect on the behaviour of tadpoles of several species of anurans. We used a mesocosm experiment to examine whether bullfrog (Rana catesbeiana) tadpoles might 1) alter their activity levels in response to variations in density and the presence of bluegill sunfish (Lepomis macrochirus), and 2) alter their daily activity cycle in response to variations in density and the presence of bluegill. The bullfrog tadpoles in our experiments showed a clear temporal pattern of activity, with activity always peaking during the evening or nighttime hours. Tadpole density had no effect on activity levels. We observed depressed activity levels in the presence of bluegill in the first observation period (30 June–1 July). Bluegill tended to depress activity levels in the second observation period (7–8 July), but this was not statistically significant. We observed elevated activity levels in tadpoles in the presence of bluegill during the third observation period (14–15 July). Neither bluegill nor tadpole density had an effect on the temporal pattern of activity in the bullfrog tadpoles. In addition to showing that fish can mediate activity in bullfrog tadpoles, our results suggest that the responses of tadpoles to the presence of predators can vary over time, and thus using a single observation could influence the conclusions that may be drawn.

Keywords: DIEL ACTIVITY, PREDATOR-PREY RELATIONSHIPS, PREDATION