Overhunting is extirpating large animals across tropical forests,
affecting tree populations and potentially global carbon cycling.
Species reliant on large-bodied seed dispersers may be particularly
negatively affected. But defaunation also affects seed predation,
trampling of seedlings, and conspecific density dependence. Therefore,
defaunation predictions must incorporate multiple plant-animal
interactions in the context of the entire tree life cycle. Because we
cannot conduct such analyses for every species, we assess whether we can
predict species' responses to defaunation based on phenotypic and
demographic traits. Using population models, Monte Carlo simulations,
and syntheses of demographic data, we found that responses to
defaunation were best explained by how hunting altered seed predation,
particularly for small-seeded angiosperms. How tree species will respond
to defaunation still cannot be precisely predicted, but ascertaining how
seed predation varies across species and hunting scenarios could greatly
enhance our understanding of changing species composition and carbon
dynamics in defaunated forests.