Three years after a population of brush-tailed possums (Trichosurus vulpecula Kerr) in 100 ha of podocarp/mixed hardwood forest in Westland had been trapped to extinction, the study area had been recolonised and the population density was lowest in the alpine forest ( > 600 m) and highest in the forest which bordered improved pasture ( < 400 m). Animals dispersed upwards from this low-altitude forest and laterally into the area along the altitude gradient. Few adults entered the area, and immature (8-18 months old) males constituted the largest dispersive class. Sex-specific and age-specific dispersal rates led to an unstable age structure in the post-kill population. A higher proportion of breeding females and good condition in the post-kill population favoured an accelerated recovery of the population in the area.