Reliability of macaques as seed dispersers

Seed dispersal is an ecological process crucial for forest regeneration and recruitment.
To date, most studies on frugivore seed dispersal have used the seed dispersal
effectiveness framework and have documented seed‐handling mechanisms, dispersal
distances and the effect of seed handling on germination. In contrast, there has been
no exploration of “disperser reliability” which is essential to determine if a frugivore is
an effective disperser only in particular regions/years/seasons or across a range of
spatio‐temporal scales. In this paper, we propose a practical framework to assess the
spatial reliability of frugivores as seed dispersers. We suggest that a frugivore genus
would be a reliable disperser of certain plant families/genera if: (a) fruits of these plant
families/genera are represented in the diets of most of the species of that frugivore,
(b) these are consumed by the frugivore genus across different kinds of habitats, and
(c) these fruits feature among the yearly staples and preferred fruits in the diets of the
frugivore genus. Using this framework, we reviewed frugivory by the genus Macaca
across Asia to assess its spatial reliability as seed dispersers. We found that the
macaques dispersed the seeds of 11 plant families and five plant genera including at
least 82 species across habitats. Differences in fruit consumption/preference between
different groups of macaques were driven by variation in plant community composition
across habitats. We posit that it is essential to maintain viable populations of
macaques across their range and keep human interventions at a minimum to ensure
that they continue to reliably disperse the seeds of a broad range of plant species in
the Anthropocene. We further suggest that this framework be used for assessing the
spatial reliability of other taxonomic groups as seed dispersers.