Cameras Reveal Nectar Robbing in Hawaiian Flowers

Some Hawaiian honeycreepers' long curved bills are the perfect implement for drawing sweet nectar from deep within a lobelioid flower. As birds reach into flowers to access the nectar stored near the base, their bills can brush against the lobelioids ' pollen-bearing structures, making hungry honeycreepers important pollinators. But some of these specialized honeycreepers have gone extinct. Shorter-billed species can now "rob" nectar — without contacting the flower's pollen-bearing structures — from the endangered flowers. A UW-led team used motion cameras to gauge how often nectar robbing occurs. The results, published Aug. 6 in Ecology and Evolution, reveal both nectar robbing and pollination visits, showcasing a broader pattern that the team previously identified by comparing bird bill length to flower length . Nectar robbing can damage flowers and leave less nectar for other potential pollinators. The researchers 3D printed a bird bill to simulate nectar robbing and track changes in nectar availability and the plants' ability to reproduce. Damaged flowers often struggled to replenish their nectar stores, but were still able to produce fruit and viable seeds. These studies are part of a larger project that aims to catalog Hawaiian bird-plant interactions through time, specifically tracking how these interactions are reshaped by extinction.