Plant-hummingbird interaction networks in an urban area: a generalist species as the protagonist in mutualistic and agonistic interactions

The maintenance of green areas within cities is essential for promoting urban biodiversity and species interactions. Here, we evaluated the interactions between hummingbirds and their visited plants over the course of a year in an urban park in Barreiras, western Bahia, Brazil. Each month, from October 2018 to September 2019, we recorded hummingbird species, the plants they visit, and their agonistic interactions. We recorded 748 legitimate visits by six hummingbirds to five plant species. Most plant species (60%) flowered continuously, and most visits were recorded in the rainy season when the network was also more specialized (H2' = 0.821). Chionomesa fimbriata was the only hummingbird recorded during all studied months. This species performed 70% of all visits recorded and was involved in most agonistic interactions (n = 68). The availability of resources affected the number of visits (p = 0.016). Tree species producing many flowers increased hummingbird diversity and concentrated most of the agonistic interactions. Plant species with continuous flowering represented a persistent supply of resources, favoring the residence of C. fimbriata within the study site. Despite the low diversity of resources, the richness of hummingbirds recorded attests to the importance of maintaining green spaces in cities to promote urban biodiversity.