Conservation biologists and agriculturalists in temperate areas favor intensified land use in designated areas to establish wildlife refuges elsewhere because they increase overall food security and biodiversity. But do the same outcomes emerge on semi-arid tropical landscapes where seasonal rainfall varies unpredictably in timing and amount?
To answer this question, we gathered 'Big Data' from remote sensors ranging from camera traps, GPS tracking tags, computer vision individual identification algorithms and satellite/drone landscape images to record wildlife and livestock movements and interactions on a series of seasonally shared landscapes. We predicted that if competition was the dominant interaction between wildlife and livestock, then both livestock production and wildlife abundance would be lower than if the dominant interaction involved mutualisms. This is because when species compete, the negative effects species have on each other wastes resources, whereas if mutualisms developed, each species profits from the actions of the others so that resource use would is augmented above levels each would gain if they lived apart. We used our ‘Big Data’ to determine 1) the degree to which competition and mutualism shaped livestock-wildlife interactions on rangelands differently impacted by cattle grazing; and 2) whether wildlife diversity and human livelihoods were enhanced more by land sharing or land sparing.
Results/Conclusions
On this Kenyan landscape, movements, associations and feeding behavior of domesticated and wild grazers involved seasonal shifts among mutualism and competition through feedbacks on rangeland quality, livestock growth and wildlife bodily condition. In particular, intensive livestock grazing on pastoral rangelands during rainy periods stimulated vegetation 'green-up' that increased livestock growth and attracted wildlife, especially zebras, and improved their condition. When the rains ceased, however, competition with dense livestock herds for non-regenerating short grasses drove zebras back to the less heavily grazed rangelands of commercial ranches. Here, their ability to process rough forage sustained them and facilitated growth of commercial herds. And although pastoralist herders don’t benefit from this mutualism, we show that by practicing 'planned grazing' in which high density herds are bunched and rotated among paddocks, pastoral cattle begin to behave like zebras eating the rough forage, improving the rangeland, increasing cattle growth and attracting wildlife.
We therefore conclude, that on semi-arid, strongly seasonal tropical rangelands, alternating mutualism and competition among wildlife and different livestock herded in different styles enhances livestock performance, wildlife condition and biodiversity on shared, as opposed to, spared, lands.