Invasive alien species pose a major economic and ecological threat worldwide,yet some aliens can have positive impacts in ecosystems by performing the functional roles of extinct natives.We investigated whether alien black rats (Rattus rattus) act as pollinators of a native plant species (Banksia ericifolia) ,replacing locally extinct native mammalian pollinators in an Australian peri-urban landscape.We first determined the amount of pollen grains carried by black rats (n=17) and compared it to that of native mammals (n=30) .Secondly,we used game cameras to measure the foraging/pollinating behaviours and inter-plant movement of mammals within artificial pollination networks.Finally,we measured the effects of mammal exclusions upon B.ericifolia seed set (n=29) .We found that black rats carried a similar pollen load and exhibited similar pollination behaviour to native mammals.Inter-plant movement was recorded for one black rat.Despite occasional destructive foraging by black rats,mammal exclusions confirmed that mammal presence (alien or native) increased the seed set of B.ericifolia.Together,these results indicate that black rats are active as substitutes for native mammalian pollinators that cannot persist in urban bushland remnants.Our results thus challenge traditional negative views of alienness: given that black rats are performing essential ecosystems services,should they be considered native?