Current theory on the evolution of pursuit-deterrent signals predicts that it may be advantageous for the prey to communicate to the predator its alertness and its ability to escape an attack. I tested these predictions by staging predator-prey encounters between A. cristatellus lizards and a model of one of its predators under natural conditions. Results supported the use of pushup displays as pursuit-deterrent signals. The intensity of signals, measured as the number of pushups given during predation episodes, was significantly positively correlated with individual physiological condition measured as endurance capacity. Because endurance capacity can be a critical aspect limiting the ability of A. cristatellus to escape a predatory attack, pushup displays can potentially communicate an individual's ability to escape an attack and, therefore, can be categorized as honest signals. Furthermore, because pushup displays are widely used during anoline social interactions, predation pressure and sexual selection may simultaneously favour the evolution of honest communication to allow both the predator and the potential mate or male rival to assess individual quality using the same signal. Copyright 1999 The Association for the Study of Animal Behaviour.