A global systematic review of frugivorous animal tracking studies and the estimation of seed dispersal distances

Abstract

Seed dispersal is one of the most important ecosystem services globally. It shapes plant populations, encourages forest succession, and has multiple, indirect benefits for humans, yet it is one of the most threatened processes in plant regeneration, worldwide. The restricted movement of local frugivores, through habitat fragmentation, is one of the main threats to seed dispersal. These restrictions alter the behaviour associated with movements before, during and after interacting with fruits and seeds. Consequently, there have been recent calls for animal movement and behaviour to be better integrated with seed dispersal studies to enable researchers to fully understand the processes that determine seed rain. To assess the current use of animal tracking in frugivory studies and to provide a baseline for future studies, we provide a comprehensive review and synthesis on the existing primary literature of global tracking studies that monitor movement of frugivorous animals. Specifically, we identify studies that estimate dispersal distances and how they vary with morphological and environmental traits. We show that over the last two decades there has been a large increase in frugivore tracking studies that determine seed dispersal distances. However, gaps across taxa and geographic distribution still exist. Furthermore, we found that certain morphological and environmental traits can be used to predict seed dispersal distances. We demonstrate that an increase in body mass significantly increases the estimated seed dispersal mean and maximum distances, as does species flight ability. Our results also suggest that protected areas have a positive effect on mean seed dispersal distances when compared to unprotected areas. We anticipate that this review act as a reference for future frugivore tracking studies to build upon, specifically to understand the drivers of movement, and to interpret how seed dispersal and other ecosystem services will be impacted by human disturbance and land use changes.