Title
Indirect effects of African megaherbivore conservation on bat diversity in the world's oldest desert
Author(s)
Laverty, Theresa M.; Berger, Joel
Published
2022
Publisher
Conservation Biology
Published Version DOI
https://doi.org/10.1111/cobi.13780
Abstract
In extreme environments, temperature and precipitation are often the main forces responsible for structuring ecological communities and species distributions. The role of biotic interactions is typically thought to be minimal. By clustering around rare and isolated features like surface water, however, effects of herbivory by desert-dwelling wildlife can be exacerbated. Understanding how species interact in these environments is critical to safeguarding vulnerable or data deficient species. Consequently, we asked whether large mammalian herbivores—African elephant, black rhinoceros, and southern giraffe—modulate insectivorous bat communities around a limiting resource—bodies of water—in the Namib Desert. We estimated megaherbivore use of sites using dung transects, summarized vegetation productivity from satellite measurements of the Normalized Difference Vegetation Index (NDVI), and described local bat communities using acoustic monitoring. We then designed structural equation models to test for direct and indirect—mediated through NDVI—relationships among megaherbivores and bat species richness and activity during both dry (November 2016 – January 2017) and wet (February – May 2017) seasons. We found site-level megaherbivore use during the dry season to be positively associated with bat activity—particularly that of open-air foraging bats—and species richness through indirect pathways. When resources were more abundant during the wet season, however, these relationships were reduced. Our results indicate that biotic interactions contribute to species distributions in desert habitats and suggest that the conservation of megaherbivores in this arid ecosystem may indirectly benefit insectivorous bat abundance and diversity. Given how misunderstood and understudied most bats are relative to these much larger and heralded mammals, such findings suggest managers pursue short-term solutions (e.g., community game guard programs, waterpoint protection near human settlements, continued ecotourism opportunities) to indirectly promote bat conservation and that research priorities expand beyond charismatic species to better document megaherbivores effects on biodiversity at other trophic levels. “When we reach… absolute deserts, the struggle for life is almost exclusively with the elements… Not until we reach the extreme confines of life, in the Arctic regions or on the borders of an utter desert, will competition cease.” – Charles Darwin, On the Origin of Species (1859)
Keywords
chiroptera; food web; foraging guild; Namib Desert; Namibia; structural equation modeling; vegetation productivity

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