Data from: Climatic variation modulates the indirect effects of large herbivores on small-mammal habitat use

Large mammalian herbivores (LMH) strongly shape the composition and
architecture of plant communities. A growing literature shows that
negative direct effects of LMH on vegetation frequently propagate to
suppress the abundance of smaller consumers. Indirect effects of LMH on
the behaviour of these consumers, however, have received comparatively
little attention despite their potential ecological significance. We
sought to understand (i) how LMH indirectly shape small-mammal habitat use
by altering the density and distribution of understorey plants; (ii) how
these effects vary with climatic context (here, seasonality in rainfall);
and (iii) the extent to which behavioural responses of small mammals are
contingent upon small-mammal density. We tested the effects of a diverse
LMH community on small-mammal habitat use using 4 years of spatially
explicit small-mammal trapping and vegetation data from the UHURU
Experiment, a replicated set of LMH exclosures in semi-arid Kenyan
savanna. Small-mammal habitat use was positively associated with tree
density and negatively associated with bare (unvegetated) patches in all
plots and seasons. In the presence of LMH, and especially during the dry
season, small mammals consistently selected tree cover and avoided bare
patches. In contrast, when LMH were excluded, small mammals were weakly
associated with tree cover and did not avoid bare patches as strongly.
These behavioural responses of small mammals were largely unaffected by
changes in small-mammal density associated with LMH exclusion. Our results
show that LMH indirectly affect small-mammal behaviour, and that these
effects are influenced by climate and can arise via density-independent
mechanisms. This raises the possibility that anthropogenic LMH declines
might interact with changing patterns of rainfall to alter small-mammal
distribution and behaviour, independent of numerical responses by small
mammals to these perturbations. For example, increased rainfall in East
Africa (as predicted in many recent climate-model simulations) may relax
constraints on small-mammal distribution where LMH are rare or absent,
whereas increased aridity and/or drought frequency may tighten them.