Nectarivory and pollination by birds in southern Australia and Europe

Nectarivory and pollination by birds is common in southern Australia. A few bird species, mostly warblers (Sylviidae), occasionally visit native flowers in Europe, though recently they have begun to visit introduced bird-pollinated species. The great difference in incidence of nectarivory and bird-pollination between Europe and Australia seems not to be due to climate, latitude or insufficiency of birds or plants. I propose the hypothesis that birds were pre-empted as pollinators by advanced, social bees in Europe.