Long corolla flowers in Tropical Andes favour nectar robbing by the Black Metaltail hummingbird: A study using citizen science and field observations

Abstract

Understanding what drives the evolution of nectar-robbing strategies is key forgaining insight into the functioning of pollination networks. However, nectar rob-bing is often an anecdotal behaviour, difficult to quantify and record through fieldobservations, especially in hummingbirds, limiting our understanding of howecological networks change across communities. Here, we report new recordsof nectar robbing by Peru´s endemic Black Metaltail (Metallura phoebe) in a high-elevation forest at ca. 4000 m a.s.l. and how this species uses either legitimatepollination feeding or nectar robbing in relation to corolla lengths. Furthermore,by analysing 452 citizen science records of photographic observations, wefound that 36% of the photographs depicting a foraging event in this specieswere actually nectar-robbing events. After identifying the plant species in all pho-tographs involving foraging events, we describe how nectar robbing conductedby this hummingbird species is strongly associated with flowers that have longercorollas. We propose that the hummingbird-flower interactions in harsh high-altitude environments, where resources and competition vary markedly acrossseasons, can offer insight into the ecological drivers of nectar-robbing behaviourin hummingbirds.