Assessing habitat suitability models for large herbivores in an elephant-impacted savanna in Botswana

Background/Question/Methods

The African elephant (Loxodonta africana) is a major driver of environmental processes in savanna landscapes. A keystone species and ecosystem engineer, elephants help maintain savanna heterogeneity and diversity. In southern Africa, however, elephants are increasingly being constrained to protected areas, raising concerns about the negative impacts that high densities of elephants may have on vegetation and wildlife. While a number of studies have examined the influence of elephant density on vegetation structure and diversity, relatively few have considered how these changes affect large herbivores. Understanding how species of varying body size and trophic group are affected by elephants will improve management by suggesting specific strategies that meet the needs of individual species and groups. To provide this information, location data for large herbivores were obtained using game drives along the riverfront of Chobe National Park, Botswana. Combining these data with remotely sensed environmental covariates in a hierarchical logistic regression model, I examine spatial distribution and habitat associations of large herbivores in Chobe.

Results/Conclusions

Distribution models were developed for the six most common species on the Chobe riverfront individually and aggregated into trophic groups. Accuracy rates for models achieved between 20-46% improvement over random classification. In general, habitat suitability was similar for mesoherbivores and elephants, though elephants appear to use the landscape at broader scales, showing a wider suitability range. Distance to water strongly influenced herbivore distributions in most models, as is expected in a semi-arid landscape. Interestingly, water was not included in models for greater kudu (Tragelaphus strepsiceros), suggesting other factors, such as predation, may drive habitat use for this species. Mesoherbivore body size had no obvious effect on distribution patterns. Chobe National Park lies at the heart of the Kavango-Zambezi Transfrontier Conservation Area (KAZA TFCA), an international network of parks and protected areas, which contain some of the highest densities of elephants on the continent. Understanding elephant impacts in Chobe will help inform effective management strategies across the KAZA region, promoting conservation of elephants and the other large herbivores that share their habitat.