Do nectar feeders in Andean nature reserves affect flower visitation by hummingbirds?

Abstract

The interactions among plants and pollinators are crucial for plant reproduction because they structure gene flow among individual plants and among populations of plants. Throughout the Neotropics there has been a strong increase in recent years in the use of artificial nectar feeders in private nature reserves to encourage ecotourism through prolonged observations of hummingbirds. Currently, there is considerable uncertainty whether artificial feeders have a detrimental effect on plant reproduction through competition or a beneficial effect through facilitation. This uncertainty is disconcerting given that nature reserves harbour many rare and endangered plants whose successful reproduction is a conservation goal. To assess whether nectar feeders affected hummingbird visitation to flowering plants, we determined visitation rates in ten flowering species in five Andean nature reserves in Ecuador. We found that visitation rates tended to be higher within 5m around the feeders than they were at 100m, 500m, or 1.5km distance to the feeders, therefore indicating that nectar feeders tended to facilitate flower visitation at close distance. Because visitation rates at 100m and 500m distance from the feeders did not differ from those at 1.5km, we suggest that feeders do not draw hummingbirds away from flower resources, but if they have an effect on flower visitation at all, they tend to facilitate flower visitation rather than reduce plant reproduction.