Structure of plant-frugivorous bird interaction networks in two high Andean forests of southwestern Colombia

Abstract

Plant-animal interactions are essential for the structure and functioning of ecosystems, especially in regions of high biodiversity such as the colombian Andes. This study focuses on the networks of frugivorous interactions between diurnal birds and plants in two high-Andean forests in southwestern Colombia, aiming to analyze the structure of these networks and determine the factors influencing their configuration. Using systematic observations in the Puracé National Natural Park and a forest remnant in Totoró, interactions were recorded over a two-year period. Standardized sampling methods were employed to quantify 454 and 307 feeding events in Puracé and Totoró, respectively. The results indicated a low overall connectivity in both networks, although a high degree of nestedness was observed. Key species like Miconia orcheotoma and Freziera canescens dominated the interactions, suggesting that factors beyond fruit abundance, such as fruit structure, a soft mesocarp, or color, may attract birds and influence network structure. At the network level, robustness showed that the networks could withstand species loss without collapsing, suggesting underlying stability despite low connectivity. In conclusion, this study highlights the importance of generalist plant species in maintaining the cohesion of frugivorous networks in high Andean forests, providing stability against environmental or anthropogenic changes. These findings underline the need to conserve both bird species and plant species to preserve the ecological functionality and ecosystem services provided by these critical ecosystems.