Plant-pollinator trait matching affects pollen transfer but not feeding efficiency of Australian honeyeaters (Aves, Meliphagidae)

Animal pollination is common among flowering plants. Increased morphological matching between floral and pollinator traits is thought to increase pollen transfer and feeding efficiency, but we lack studies that empirically demonstrate this. Working with Australian honeyeaters, we find that there is positive correlation between bill-corolla matching and pollen deposition at flowers, but no correlation with how efficiently birds can extract floral nectar. The species with the lowest bill-corolla matching deposited the fewest pollen grains but had the highest feeding efficiency, showing that bill-corolla matching expectations were met on the plant side of this interaction but not on the pollinator side. Finally, we find different interspecific patterns of pollen deposition at the scales of a single flower visit versus the landscape, due to differences in patterns of plant visitation. This work illustrates the need for more studies that directly correlate trait matching to fitness proxies of plants and avian pollinators.