The effect of hunger on the strength and duration of the antipredator behavioral response of green frog (Rana clamitans) tadpoles

The activity level of prey reflects a trade-off between predation risk and foraging gain. A number of theoretical and empirical studies have shown that a prey's energetic state or the level of its resource should influence this trade-off (i.e., what the optimal activity level at a level of predation risk is). Here, I show that the energetic state of prey may also influence the duration of their antipredator behavioral response. Green frog tadpoles (Rana clamitans) reduced their activity level for a shorter time during exposure to the chemical cue of predatory larval dragonflies (Anax spp.) as their time since last feeding increased (i.e., as their energetic state decreased). Interestingly, the tadpoles strongly reduced their activity level upon cue exposure in all treatments. Thus, the relative activity level of tadpoles at different energetic states varied over time.