Plant origin and fruit traits shape fruit removal patterns by native birds in invaded plant communities

Abstract

Biotic interactions and mutualisms in particular have an important role in ecosystem structure and functioning as well as in the maintenance of biodiversity. Understanding how communities respond to the introduction of non-native species and what determines the establishment of novel interactions between native and introduced species will help in determining the potential impacts of biological invasions. The aims of this work were to assess patterns of frugivory and fruit removal in environments with invasion of non-native fleshy-fruited plants and to evaluate whether novel associations between native frugivores and non-native plants are determined by fruit traits. For this we selected eight study sites in areas with different degrees of invasion of non-native fleshy-fruited plants. In each site, we measured fruit availability and fruit traits of native and non-native plants. In addition, we conducted direct frugivory observations. We found that native and non-native fruits differed based on morphological trait variables, such as fruit weight and dimensions. Only two birds, Elaenia albiceps (smaller and migrant) and Turdus falcklandii (bigger and resident), are the main frugivorous present in the area. At the scale of the community of frugivores, neither visit nor fruit removal rates differ between natives and non-natives. However, at the species scale, while E. albiceps preferentially foraged on native plants, T. falcklandii preferred non-natives. Thus, some generalist frugivorous species like T. falcklandii can play a key role in promoting the invasion of non-native plants.