The red-rumped parrot (Psephotus haematonotus), which appears to be undergoing range expansion, started colonising metropolitan Melbourne ~30 years ago. The factors that have facilitated this colonisation have not been evaluated. We investigated aspects of the parrot’s ecology at six parkland sites through late autumn and winter 2006 to elucidate these factors. The predominantly ground-feeding red-rumped parrot consumed mainly seeds of exotic grass and herb species, four of which were particularly important in providing a continuous winter food resource. Two of these species were common turf grasses and their visible and concealed seeds provided >50% of the diet. Sites occupied by parrots had relatively more native trees, tall trees and dense canopy cover than unoccupied sites; this may be important in providing suitable daytime and nocturnal roost sites. Little aggressive interference competition occurred with other ground-feeding birds. Mean population density in occupied sites was 1.3 parrots ha^–1. Mean flock size was 10 ± 6 and, on average, males comprised 67 ± 19% of a flock’s members. We suggest that abundant, continuously available food (seed) resources, apparently limited competition for food and the presence of suitable roosting sites are probably important in facilitating winter occupancy of parkland by red-rumped parrots in Melbourne.