Effect of the presence of nectar feeders on the breeding success of Salvia mexicana and Salvia fulgens in a suburban park near Mexico City

The use of nectar feeders has grown a lot as a result of people wanting to attract hummingbirds to their gardens. This has caused an increment in the density and diversity of these birds in urban and suburban habitats. The feeders not only represent a bonanza resource for hummingbirds but they can also result in reduced visitation to native plants. We experimentally assessed the effect of placing nectar feeders in the vicinity of two native plant species in a suburban area of Mexico City. The plants with feeders showed a reduced visitation rate and in one case (Salvia fulgens) produced fewer seeds than the controls. Salvia mexicana was not only visited by hummingbirds but it was also by bees that were not attracted to the feeders, probably resulting in the lack of effect on this plant. Native plants in urban and suburban habitats can be threatened by reduced visitation rates and reduced seed sets resulting from the use of feeders. (C) 2006 Elsevier Ltd. All rights reserved.