Less is more: Lowering cattle stocking rates enhances wild herbivore habitat use and cattle foraging efficiency

Authors: WELLS, HARRY - University Of Leeds; CREGO, RAMIRO - Smithsonian'S National Zoo & Conservation Biology Institute; EKADELL, JACKSON - Mpala Research Centre And Wildlife Foundation; NAMONI, MATTHEW - Mpala Research Centre And Wildlife Foundation; KIMUYU, DUNCAN - Karatina University; ODADL, WILFRED - Egerton University; Porensky, Lauren; DOUGILL, ANDREW - University Of Leeds; STRINGER, LINDSAY - University Of Leeds; YOUNG, TRUMAN - University Of California

Submitted to: Frontiers in Ecology and Evolution
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/13/2022
Publication Date: 2/11/2022
Citation: Wells, H.B., Crego, R.D., Ekadell, J., Namoni, M., Kimuyu, D.M., Odadl, W.O., Porensky, L.M., Dougill, A.J., Stringer, L.C., Young, T.P. 2022. Less is more: Lowering cattle stocking rates enhances wild herbivore habitat use and cattle foraging efficiency. Frontiers in Ecology and Evolution. 10. Article 825689. https://doi.org/10.3389/fevo.2022.825689.
DOI: https://doi.org/10.3389/fevo.2022.825689

Interpretive Summary: Over a quarter of the world’s land surface is grazed by cattle and other livestock, which are replacing wild herbivores, particularly outside protected areas. Ensuring that livestock production and conservation practices are compatible is critical for the future of rangelands. However, how cattle stocking rate affects wild herbivore populations is poorly understood, in part because most studies simply compare cattle presence versus absence. And although much is known about the impacts of cattle stocking rate on cattle foraging efficiency and productivity, the potential tradeoffs or co-benefits between livestock production and wildlife conservation have been rarely investigated. We addressed this knowledge gap using a long-term exclosure experiment in a Kenyan savanna. Our results show that, overall, high cattle stocking rates were detrimental to both cattle foraging efficiency and the habitat use of the two dominant wild mesoherbivores (zebra and eland) that we investigated. We also found that megaherbivores (elephant and giraffe) increased zebra habitat use, but that this effect was negated at high cattle stocking rates. These findings are important to guide ecosystem management and restoration efforts across African mixed-use rangelands by providing novel insights into the tradeoffs between, and potential win-wins for, cattle production and wild herbivore conservation.

Technical Abstract: Over a quarter of the world’s land surface is grazed by cattle and other livestock, which are replacing wild herbivores and widely regarded to be drivers of global biodiversity declines. The effects of livestock presence versus absence on wild herbivores are well documented. However, the environmental context-specific effects of cattle stocking rate on biodiversity and livestock production is poorly understood, precluding nuanced rangeland management recommendations. To address this, we used a long term exclosure experiment in a semi-arid savanna ecosystem in central Kenya that selectively excludes cattle (at different stocking rates), wild mesoherbivores, and megaherbivores. We investigated the individual and interactive effects of cattle stocking rate (zero/moderate/high) and megaherbivore (> 1000 kg) accessibility on habitat use (measured as dung density) by two dominant wild mesoherbivores (50-1000 kg; zebra Equus quagga and eland Taurotragus oryx) across the ‘wet’ and ‘dry’ seasons. To explore potential tradeoffs or co-benefits between cattle production and wildlife conservation, we tested for individual and interactive effects of cattle stocking rate and accessibility by wild mesoherbivores and megaherbivores (collectively, large wild herbivores) on the foraging efficiency of cattle across both seasons. Eland habitat use was reduced by cattle at moderate and high stocking rates across both dry and wet seasons and regardless of megaherbivore accessibility. We observed a positive effect of megaherbivores on zebra habitat use at moderate, but not high, stocking rates. Cattle foraging efficiency (g dry matter step-1 min-1) was lower in the high compared to moderate stocking rate treatments during the dry season, and was non-additively reduced by wild mesoherbivores and high cattle stocking rates during the wet season. These results show that, overall, high stocking rates are detrimental to wild mesoherbivore habitat use and cattle foraging efficiency, while reducing to moderate stocking rates can benefit zebra habitat use and cattle foraging efficiency. Our findings suggest that ecosystem management and restoration efforts across African mixed-use rangelands that involve reducing cattle stocking rates may represent a win-win for wild herbivore conservation and individual performance of livestock.