SREL Reprint #3860

Bottom-up space use with top-down temporal risk buffering in arid herbivore communities

John Heydinger1,2, Uakendisa Muzuma3,4, Tammy Hoth-Hanssen5, Genevieve Finerty6, Natalia Borrego6,
and James Beasley7

1Savannah River Ecology Laboratory, University of Georgia, Aiken, South Carolina, USA
2Lion Rangers Program, Kunene, Namibia
3Ministry of Environment, Forestry and Tourism, Windhoek, Namibia
4Witwatersrand University, Johannesburg, South Africa
5Namibian Lion Trust, Kamanjab, Namibia
6Max Planck Institute of Animal Behavior, University of Konstanz, Konstanz, Germany
7Savannah River Ecology Laboratory, Warnell School of Forestry, University of Georgia, Aiken, South Carolina, USA

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.

Keywords: browsers; camera traps; diel overlap; grazers; landscape of fear; megaherbivores; Namibia; predator–prey

SREL Reprint #3860

Heydinger, J., U. Muzuma, T. Hoth-Hanssen, G. Finerty, N. Borrego, and J. Beasley. 2026. Bottom-up space use with top-down temporal risk buffering in arid herbivore communities. Ecology and Evolution 16(e72836). 

This information was provided by the University of Georgia's Savannah River Ecology Laboratory (srel.uga.edu).