Effectiveness Of Wildlife Underpasses And Culverts In Connecting Elephant Habitats: A Case Study Of New Railway Through Kenya’s Tsavo National Parks (2021)

Abstract Transportation networks can be a major impediment to wildlife movements. We assessed the use of wildlife underpasses and culverts along a newly constructed railway in Kenya's Tsavo National Parks by African elephants (L. africana). We collared ten elephants with GPS satellite transmitters within 20 km of the railway in March 2016 and analysed their movement data to March 2019. Eight elephants used the underpasses although one did not cross the adjacent highway. The remaining two neither used the underpasses nor crossed the highway despite ranging in the vicinity. Their median speed significantly increased to 0.65 km/hr from 0.45 km/hr before crossing the railway, then slowed to 0.32 km/hr after crossing. Females in family groups moved faster than the lone bulls when using the underpasses. Seventy-eight per cent of all crossings made were at night. The fast speeds and the nocturnal patterns are behavioural responses of elephants in risky landscapes or under stress. Disturbance from vehicles traffic on the adjacent highway and from newly developed human settlements may have limited use of underpasses. Wildlife crossing structures, signage and speed bumps along the highway; relocation of the illegal human settlements; and inter-agency coordination are requisites for enhancing Tsavos' elephant habitat connectivity.