Evolutionarily stable strategies(ESSs) of asymmetric animal contests are formulated by using Bayesian games. A criterion which is a generalization of that of Abakukus(\cite{Ab}) and a strengthened Selten's theorem(\cite{Se}) are given. As an example, a Hawk-Dove game with roles, in which the animals having the same role may possibly meet each other, is investigated and all possible Nash equilibria and ESSs are obtained for given parameters.