Nectar sources used by birds in monsoonal north-western Australia: a regional survey

We document the flora that provides nectar for birds in monsoonal north-western Australia, and examine the relationship between floral morphology and bird morphology in the region. Twenty-four regular nectarivores (21 honeyeaters, two lorikeets, one white-eye) and 29 opportunist species have been observed probing the flowers of 116 species of plants from 28 families. Amongst the nectar sources, the Myrtaceae is dominant in both the number of species and frequency of use, followed distantly by the Proteaceae and Loranthaceae. Variation between bird species in patterns of use of different floral structures primarily reflected the habitats occupied rather than shared or co-evolved morphology. Woodland birds made particular use of staminiferous cups, mangal specialists particular use of open sepaliferous and petaliferous flowers, and forest specialists and habitat generalists intermediate use of these flower types. Bird-flower relationships in monsoonal Australia may be generalised because of a combination of the dominance of mass-flowering myrtaceous trees, aridity during past glacials that may have eliminated specialists from the system, and perhaps also because many nectar sources are shared with bats.