Hummingbird-plant visitation networks in agricultural and forested areas in a tropical dry forest region of Guatemala

Abstract

Tropical dry forest, especially in Central America, has experienced high rates of deforestation primarily due to conversion to agricultural fields and pastures. Yet little is known about the effects of the conversion of Central American tropical dry forest on the pollination interactions between hummingbirds and native plants. A better understanding of hummingbird-plant communities in transformed tropical dry forest ecosystems can be useful for the development of conservation strategies to maintain hummingbird diversity and plant-pollinator interactions. As a consequence, in this study, we evaluated how habitat conversion and seasonality affect the total number of recorded hummingbird-plant interactions in a tropical dry forest of Central America. We used network analysis to assess the effects of habitat conversion on the structure and dynamics of the plant-hummingbird assemblages at our study sites. Data on hummingbird visitation to native flowering plants were collected along four transects located in patches of tropical dry forest and four transects in agricultural areas. Each transect was visited twice during the dry season and twice during the rainy season. Our data suggest that, at a local scale, seasonality is a stronger predictor than habitat type of the recorded number of hummingbird-plant interactions at our study sites. The lack of differences in the number of interactions with respect to habitat type is probably related to the generalist nature of our studied hummingbird-plant assemblages, allowing plants and hummingbirds to persist and form new interactions in the transformed environment. Our data also suggest that, although hummingbird-plant assemblages can persist in agricultural environments, habitat conversion to agriculture can cause changes in network patterns such as lower interaction diversity, lower partner diversity, and a higher level of generalization, which have negative implications for the conservation of mutualist pollination interactions. Therefore, our data highlight the importance of natural and semi-natural tropical dry forest remnants within agricultural landscapes for the conservation of pollinators and pollination services necessary for the reproduction of native plants.