TY - JOUR
T1 - Climatic variation modulates the indirect effects of large herbivores on small-mammal habitat use
AU - Long, Ryan A.
AU - Wambua, Alois
AU - Goheen, Jacob R.
AU - Palmer, Todd M.
AU - Pringle, Robert Mitchell
N1 - Funding Information:
We thank the Government of Kenya for permission to conduct this research. Capture and handling of small mammals was approved by the Institutional Animal Care and Use Committee at the University of Wyoming (protocol SKMBT-60112030515200) and conducted with permission from the Kenya Government (permit NCST/5/002/R/656). This work and its participants were supported by the US National Science Foundation (DEB-1355122 to C. Tarnita and R.M.P.; EAGER-1547679 to J.R.G.). We thank Ali Hassan, Samson Kurukura, M. Mohamed, S. Kinyua, S. Lima, G. Charles, E. DeFranco, R. Hohbein, and the staff of Mpala Research Centre for invaluable field assistance and support. We also thank T. Johnson for statistical advice and two anonymous reviewers for insightful comments and suggestions that have greatly improved the manuscript and its presentation. The authors declare that they have no conflict of interest.
Publisher Copyright:
© 2017 The Authors. Journal of Animal Ecology © 2017 British Ecological Society
PY - 2017/7
Y1 - 2017/7
N2 - 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.
AB - 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.
KW - African savannas
KW - climate change
KW - context dependence
KW - contingency
KW - ecosystem engineering
KW - habitat use
KW - herbivory
KW - trait-mediated indirect interactions (TMII)
KW - ungulates and elephants
KW - zoonotic disease risk
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U2 - 10.1111/1365-2656.12669
DO - 10.1111/1365-2656.12669
M3 - Article
C2 - 28342277
AN - SCOPUS:85018969846
SN - 0021-8790
VL - 86
SP - 739
EP - 748
JO - Journal of Animal Ecology
JF - Journal of Animal Ecology
IS - 4
ER -