Data from: Insectivorous birds and bats outperform ants in the top-down regulation of arthropods across strata of a Japanese temperate forest

Birds, bats, and ants are recognized as significant arthropod predators.
However, empirical studies reveal inconsistent trends in their relative
roles in top-down control across strata. Here, we describe the differences
between forest strata in the separate effects of birds, bats, and ants on
arthropod densities and their cascading effects on plant damage. We
implemented a factorial design to exclude vertebrates and ants in both the
canopy and understory. Additionally, we separately excluded birds and bats
from the understory using diurnal and nocturnal exclosures. At the end of
the experiments, we collected all arthropods and assessed herbivory
damage. Arthropods responded similarly to predator exclusion across forest
strata, with a density increase of 81% on trees without vertebrates and
53% without both vertebrates and ants. Additionally, bird exclusion alone
led to an 89% increase in arthropod density, while bat exclusion resulted
in a 63% increase. Herbivory increased by 42% when vertebrates were
excluded and by 35% when both vertebrates and ants were excluded. Bird
exclusion alone increased herbivory damage by 28%, while the exclusion of
bats showed a detectable but non-significant increase (by 22%). In
contrast, ant exclusion had no significant effect on arthropod density or
herbivory damage across strata. Our results reveal that the effects of
birds and bats on arthropod density and herbivory damage are similar
between the forest canopy and understory in this temperate forest. In
addition, ants were not found to be significant predators in our system.
Furthermore, birds, bats, and ants appeared to exhibit antagonistic
relationships in influencing arthropod density. These findings highlight,
unprecedentedly, the equal importance of birds and bats in maintaining
ecological balance across different strata of a temperate forest.