Data from: Gardeners of the forest: hornbills govern the spatial distribution of large seeds

Seed dispersal by frugivores is vital to the maintenance of tree diversity
in tropical forests. However, determining the influence of different
frugivores over the distribution of their food plants is difficult, given
the complexity of these interactions in the tropics. Consequently, most
studies have been restricted to small scales, examining seed dispersal and
establishment associated with nests, roosts or fruiting trees. Here, we
evaluate the role of frugivorous hornbills in dispersing seeds at spatial
scales of 1 ha. We monitored hornbills and seed rain at a tropical forest
site in north-east India. We quantified the abundance of hornbill food
plants and recruits of large-seeded plants. We estimated removal rates of
dispersed, large seeds to determine post-dispersal seed fate. We found
that the distribution of large-seeded canopy food plants influenced the
distribution of the relatively abundant Rhyticeros undulatus. The overall
distribution of hornbills resulted in spatially-contagious seed rain
patterns for the large-seeded plant species. Patches with canopy food
plants had a higher recruit diversity. Our results show a positive
feedback between distribution of rare but important hornbill food plants,
hornbills and distribution of seeds and saplings of large-seeded plants in
the landscape. Widespread loss of hornbills due to hunting and habitat
loss in the region, have likely disrupted these feedback mechanisms that
are critical for tree species regeneration.