We present numerical results on a stochastic population dynamics model with reproduction rates depending on the density of particles in a neighborhood. In order to investigate the role of fluctuations some characteristics of the model are compared with those computed from its deterministic (noise-less) density equation. In particular, we study the stationary density of particles when a pattern is developed and the typical size of the clusters of particles.Financial support from MEC (Spain) and FEDER through project CONOCE2 (FIS2004-00953) is greatly acknowledged. C.L. is a Ramón y Cajal fellow.Peer reviewe
