Seed predator or seed nurturer? The critically endangered Puerto Rican parrot increases germination of large-fruited Caribbean plants

Abstract

Frugivores play an essential role in the dispersal and germination of the seeds they consume, a service that might be particularly impacted in insular systems such as the Caribbean, where communities of large, native frugivores have been detrimentally affected because of human activities. Here, we evaluate the potential of the Critically Endangered Puerto Rican Parrot (Amazona vittata) to restore lost mutualistic interactions with native Caribbean plants. Specifically, we utilized captive parrots to assess if fruit size influences whether parrots destroy or depulp seeds of consumed fruits. Furthermore, we investigated whether germination success was higher after parrots depulped consumed fruits compared to control or manually depulped fruits. We evaluated fruits of 15 plant species and found that parrots were significantly more likely to depulp rather than predate larger fruits. Furthermore, for all species in which depulping occurred, seeds depulped by parrots exhibited the highest germination success compared to both control and manually depulped seeds. Our results indicate that fruit size traits dictate how parrots interact with consumed fruits and that depulping actions provided by the parrots significantly increase germination success of native large-fruited plants, highlighting the conservation value of this threatened avian group within the Caribbean.