This paper is devoted to the existence of Hopf bifurcations in predato
r-prey systems under the assumption that the predators show social beh
aviour. Using the theory of Hopf bifurcation, we prove that the social
coefficient appears as an adequate bifurcation parameter. Also, some
numerical results are presented in order to discuss the structure of b
ifurcating solutions. (C) 1997 Elsevier Science B.V.