Across the western Cape of South Africa can be found small plants in the Iris family called Babiana. Flitting between them are sunbirds, small colourful birds like the African version of hummingbirds, that drink the nectar of flowers and in doing so pollinate them. New research to be published early next year in a special edition on plant mating in the Annals of Botany (http://j.mp/pRSzzC) by De Waal, Anderson and Barrett shows that while birds are important for plant reproduction, when it comes to sex Babiana don't put all their eggs in one basket.
Babiana interest biologists because they seem to have a very specialised adaptation. Spencer Barrett of the University of Toronto said: "Sunbirds fill a similar evolutionary niche to hummingbirds, but there's a key difference. Hummingbirds feed on the wing by hovering. In contrast, sunbirds prefer to perch when they feed. What makes Babiana special is that some species have evolved a specialised bird perch, so what we did was set out to investigate how this functions."
The research consisted of fieldwork across the western Cape, examining Babiana and making observations of the sunbirds that pollinate them. Barrett said: "What we found is when sunbirds visit Babiana ringens, they always land on this perch and then turn upside down to feed on nectar from the the ground-level flowers. In contrast Babiana carminea doesn't have a perch, and here we found that sunbirds land on the ground and probe flowers to feed on nectar. Ground level flowers are highly unusual in bird-pollinated plants because of the likely predation risk and to find two contrasting feeding strategies among related species is remarkable"
"Babiana avicularis has a perch, but these plants are only visited by the southern double collared sunbird. This is a smaller sunbird, and it looks like Babiana avicularis may have evolved
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