Multi-year Use of the Standard Gauge Railway Underpasses by Mammals in Tsavo, Kenya: Influence of Underpass Dimensions, Infrastructure and Ecology
Abstract Rail and road infrastructure is essential for economic growth and development but can cause a gradual loss in biodiversity and degradation of ecosystem function and services. We assessed influence of underpass dimensions, fencing, proximity to water and roads, Normalized Difference Vegetation Index (NDVI), presence of other species and livestock on underpass use by large and medium-sized mammals. Results revealed hyenas and leopards used the underpasses more than expected whereas giraffes and antelopes used the underpasses less than expected. Generalized linear mixed effects models (GLMMs) revealed that underpass height influenced their use by wildlife, with several species preferring to use taller underpasses. Electric fencing increased underpass use by funneling species towards underpasses, except for elephants and black-backed jackal for which it reduced underpass passage. GLMMs also revealed that the use of underpasses by livestock reduced the probability of their use by nearly 50% of wildlife species. Carnivore species were more likely to cross underpasses used by their prey. Buffalo, livestock, and hyenas used underpasses with higher NDVI and near water sources while baboons, dik-diks and antelope avoided underpasses with high NDVI. The findings suggest a need for diverse, and comprehensive approach for mitigating the negative impacts of rail on African wildlife.