Data from: Large frugivores matter: insights from network and seed dispersal effectiveness approaches

1.While large avian frugivores are known to be key dispersers for
large‐seeded tree species, their role in community‐wide plant‐disperser
networks is still poorly known. Large avian frugivores are also among the
most threatened due to anthropogenic impacts. 2.We evaluated the role of
large avian frugivores in a plant‐disperser community by a) determining
whether the plant‐disperser community was modular, with a distinct
community of large frugivores (thereby highlighting their importance), b)
determining relative qualitative and quantitative roles played by
large‐bodied frugivores vis‐à‐vis other frugivores and c) determining
impacts of large‐bodied frugivore loss on the plant‐disperser community.
3.The study was carried at a tropical forest site in north‐east India
which is part of the Eastern Himalaya Biodiversity Hotspot. We collected
tree watch data (2055 h) from 46 tree species, which represented 85% of
tree species that are predominantly bird‐dispersed in the area. 4.We found
that the plant‐disperser community was modular, with a distinct module of
large‐seeded tree species and large frugivores. Intermediate‐sized
frugivores such as barbets and bulbuls were the most connected, while
large‐sized frugivores, such as hornbills and imperial‐pigeons were
moderately well‐connected. Qualitative and quantitative roles played by
different dispersers varied across the gradient of frugivore body size.
Hornbills, the largest avian frugivores, consumed a significantly greater
number of fruits and swallowed larger proportions of fruits compared to
other avian groups. In comparison to similar‐sized frugivores,
imperial‐pigeons fed on larger‐sized fruits, highlighting their importance
for dispersal of large‐seeded plants. Under simulated extinction
scenarios, larger extinction cascades weren't necessarily caused by
larger frugivores, however, extinctions of certain large‐bodied frugivores
(hornbills, imperial‐pigeons) caused extinction cascades. 5.Integrating
information from networks and seed dispersal effectiveness approaches
enabled a better understanding of large frugivore role in a
plant‐disperser community. While large‐bodied frugivores may not be
playing a central role in plant‐disperser communities, they are crucial as
seed dispersal service providers for large‐seeded plants. In conjunction
with the reported local extinctions of large frugivores like hornbills
from the south Asian region, this study's findings highlight the
irreplaceable quantitative and qualitative impacts that tropical plant
communities are likely to experience in the future.