CALLERS AND SATELLITES - CHORUS BEHAVIOR IN ANURANS AS A STOCHASTIC DYNAMIC GAME

Males often compete for mates using alternative tactics whose relative success could be simultaneously influenced by four factors: subsequen t behaviour, physiological state, the frequency of expression of alter native tactics and the density of competing males. Here the payoffs to two alternative male mating tactics (call and satellite) were examine d in anurans using a stochastic dynamic game. The basic model consider s an iteroparous species with a prolonged breeding season and fairly l ow energetic costs and predation risks. The model assumes that female chorus attendance is affected by weather, time of year and male chorus ing intensity. Results show that interactions between energetic costs of calling, density-dependent predation risk and female arrival rates, and frequency-dependent mating success produce distinct temporal wave s of male chorusing despite continuously favourable environmental cond itions. Relative to second-year males, first-year males attended choru ses less often and were more likely to become satellites. When the ene rgetic costs of calling were increased, waves became shorter and less frequent, and some older calling males switched to satellite behaviour . Satellites were less common when breeding season length was constrai ned by extrinsic factors such as seasonal weather patterns. Extrinsic constraints may also affect system stability: if female arrival rates are independent of male chorusing intensity, an evolutionarily stable strategy occurs only if the breeding season is short. Even without ext rinsic constraints, the breeding season may be short if predation rate s on adults are sufficiently high, or if satellites intercept a large fraction of incoming females. Thus, the 'explosive' breeding systems o bserved in many anuran species could result from either biotic or abio tic causes. (C) 1996 The Association for the Study of Animal Behaviour