Estudo comportamental de beija-flores (Aves, Trochilidae) e seus recursos florais em São Carlos, SP, Brasil

Abstract

Hummingbirds have a strong relationship with plants. They are animals specialized in the consumption of floral nectar and play an important role in the pollination of neotropical plants. The spatial and temporal availability of flowers directly influence the foraging strategies exhibited by hummingbirds which must constantly seek out and consume in order to satisfy their metabolic needs. The body mass / weight ratio and the hovering flight style results in high metabolic rates, which make these animals good basic models for behavioral and energy studies. The objective of this work was to evaluate the assemblage of hummingbirds and their floral resources within an altered Cerrado area at the Federal University of São Carlos and to analyze the territorial behavior of hummingbirds on a resource patch of Spathodea campanulata, a plant originated in Africa and widely used as ornament in urban centers. The Federal University of São Carlos, Campus São Carlos is divided into two large areas, one urban and other non-urban, which contains a natural Cerrado fragment, Eucalyptus plantation, gallery forests that holds two important streams to the region and a regenerating secondary savanna formation. Seven species were recorded using the resources of S. campanulata and 202 animal-plant interactions were registered during flowering period of this exotic plant, while in the non-urbanized region of the campus, 156 interactions were recorded between 10 hummingbirds and 11 plant species throughout 2018. On a larger scale, the urban environment may lead to a greater number of interactions between hummingbirds and plants, mainly due to the wide diversity and annual availability of exotic plants, but the altered natural environment still presents a greater richness of species of hummingbird, even with low frequencies of visits. Eupetomena macroura was found to be a territorialist species and dominant on the region. Searching the resources of S. campanulata, it remained in perches nearby the foraging site more frequently (58,3%) than it flew to other locations (38,8%). In the Cerrado area of the campus, the hummingbirds used more trap-lining strategy than territorialism. The only territorialist event occurred with E. macroura under Qualea multiflora resources, but it occurred for a short period of time. Four plants with ornitofilia syndrome were identified, but the highest frequencies of visits occurred in non-ornithophylous plants. The presence of non-ornithophylous plants in a biological system may attract more hummingbirds and indirectly influence the reproduction of ornithophylous plants. Thus, the urban environment can be a great escape area for hummingbirds as it provides abundant resources for this group. Hummingbirds can be a bridge between the natural and urban environment, we suggested integrated studies to better understand the dynamics across both communities and how generalist hummingbirds can contribute to the maintenance of the ornithophilous vegetation in natural areas.