Bottom‐Up Space Use With Top‐Down Temporal Risk Buffering in Arid Herbivore Communities

TL;DR

In arid regions, herbivores adjust their space use based on environmental factors and avoid predators by being active during the day, reducing overlap with nocturnal carnivores.

Contribution

The study introduces a hierarchical landscape of fear framework showing how bottom-up and top-down factors jointly shape herbivore behavior in unfenced arid systems.

Findings

Herbivores show low diel overlap with nocturnal predators due to temporal buffering of risk.

Bottom-up factors like dry-season progression and habitat structure strongly influence herbivore space use.

Spatial responses to predators are modulated by environmental context, highlighting spatiotemporal plasticity.

Abstract

The landscape of fear (LOF) framework predicts that prey adapt their behavior to mitigate predation risk, yet the framework's expression in resource‐limited, unfenced systems remains poorly understood. Across seven large herbivore species in an unfenced arid system, space use is governed by bottom‐up constraints while predator risk is buffered in time, producing consistent low diel overlap with nocturnal carnivores and trait‐dependent moderation of spatial responses. We used camera trap data from northwest Namibia to examine how five herbivore species (gemsbok
Oryx gazella
, southern giraffe
Giraffa giraffa
, greater kudu
Tragelaphus strepsiceros
, Hartmann's mountain zebra
Equus zebra
, springbok
Antidorcas marsupialis
) and two megaherbivores (black rhinoceros
Diceros bicornis
, African bush elephant
Loxodonta africana
) navigate bottom‐up environmental constraints and top‐down predation risk from lions (
Panthera leo
) and spotted hyenas (
Crocuta crocuta
). We tested four hypotheses: (1) that bottom‐up environmental constraints would explain more variance in herbivore space use than predator covariates; (2) that herbivores would reduce diel overlap (Δ) with nocturnal predators rather than vacating resource patches; (3) that megaherbivores would show minimal spatiotemporal avoidance of predators, relative to smaller herbivores; and (4) that herbivores would respond reactively to recent predator presence, rather than proactively by avoiding areas of chronic predator activity. Our findings support a hierarchical LOF in which bottom‐up constraints (dry‐season progression, visibility for grazers, habitat structure for browsers) contribute to herbivore space use and top‐down predator pressures guide temporal activity: most species exhibited strongly diurnal activity, resulting in low temporal overlap with nocturnal carnivores (Δ ≈0.11–0.21 for grazers; Δ ≈0.06–0.26 for browsers). By contrast, spatial responses to predator presence were modulated by environmental context, reinforcing the importance of spatiotemporal plasticity. These results advance understandings of predator–prey dynamics, particularly in dryland ecosystems. We suggest refinements to the LOF framework for multi‐predator, resource‐constrained landscapes.

Across seven large herbivore species in an unfenced arid system, space use is governed by bottom‐up constraints while predator risk is buffered in time, producing consistent low diel overlap with nocturnal carnivores and trait‐dependent moderation of spatial responses.

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