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Many species of large wildlife have declined drastically worldwide. These
reductions often lead to profound shifts in the ecology of entire
communities and ecosystems. However, the effects of these large wildlife
declines on other taxa likely hinge upon both underlying abiotic
properties of these systems and on the types of secondary anthropogenic
changes associated with wildlife loss, making impacts difficult to
predict. To better understand how these important contextual factors
determine the consequences of large-wildlife declines on other animals in
a community, we examined the effects of three common forms of
large-wildlife loss -removal without replacement (using fences), removal
followed by replacement with domestic stock, and removal accompanied by
crop agricultural use- on small mammal abundance, diversity, and community
composition, in landscapes that varied in several abiotic attributes
(rainfall, soil fertility, land-use intensity) in central Kenya. We found
that small mammal communities were indeed heavily impacted by all forms of
large-wildlife decline, showing, on average: i) higher densities, ii)
lower species richness per site, and iii) different species assemblages in
sites from which large wildlife were removed. However, the nature and
magnitude of these effects were strongly context-dependent. Rainfall, type
of land-use change, and the interaction of these two factors were key
predictors of both the magnitude and type of responses of small mammals.
The strongest effects, particularly abundance responses, tended to be
observed in low-rainfall areas. Whereas isolated wildlife removal
primarily led to increased small mammal abundance, wildlife removal
associated with secondary uses (agriculture, domestic stock) had much more
variable effects on abundance and stronger impacts on diversity and
composition. Collectively, these results 1) highlight the importance of
context in determining the impacts of large-wildlife decline on small
mammal communities, 2) emphasize the challenges in extrapolating results
from controlled experimental studies to predict the effects of wildlife
declines that are accompanied by secondary land-uses, and 3) suggest that,
because of the context-dependent nature of the responses to large-wildlife
decline, large-wildlife status alone cannot be reliably used to predict
small mammal community changes.
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