Kenya’s largest elephant herd is spending sleepless nights, over how to safely cross and live with the new Standard Gauge Railway (SGR), that cuts deep into their home.
To cope with the line, the elephants, numbering about 16,000 are uncharacteristically crossing at night; crossing at stressfully high speeds while a third is not crossing at all.
“These are all strategies of risk avoidance and highly stressful,” says a team of experts who have been studying the impact of the new line on the elephants of Tsavo.
Crossing at night
Usually, the experts say elephants are mainly active in the daytime. But since the advent of the new line across the Tsavo national parks resident elephants are likely to cross at night.
“We found that the elephants used provided underpasses predominately at night, which indicates a risk avoidance strategy, as elephants are largely active during daytime hours,” wrote the experts in the African Journal of Ecology in May 2021.
Between 2014 and 2017 Kenya constructed a new 487 km Standard Gauge Railway stretching from Mombasa to Nairobi cities. The railway has since been operationalized.
A significant part of the railway, 133 km however cuts across one of Kenya’s largest wildlife conservation area.
The Tsavo Conservation Area (TCA), covers about t 43,000Km² encompassing Tsavo East, Tsavo West, and Chyulu Hills national parks.
It also covers a number of large community-groups ranches, considered important for wildlife dispersal and connectivity.
The 133km section of the railway cutting across the conservation area is raised on an embankment and fenced on either side.
This, the study authors say poses a significant conservation challenge despite provisions of wildlife underpasses along this new railway.
There are six wildlife underpasses (70 m long and 6 m high) that connect Tsavo East and Tsavo West national parks positioned at about every 9.5 km.
In addition to these six wildlife underpasses, there are also nine large bridges available for wildlife use.
GPS satellite transmitters
The researchers from Save the Elephants, Nairobi, Kenya Wildlife Service, Tsavo Trust, Kenya, Zoological Society of London, UK and Oxford University, UK, were assessing the effectiveness of the underpasses and culverts in enabling elephant movement in the area.
The team had collared 10 elephants with GPS satellite transmitters and studied their movement (and by extension that of their families) for a three-year period.
Thirty percent of the studied elephants did not cross the railway despite moving close to the underpasses and bridges. “This indicates crossing the railway underpasses was clearly a risk for the elephants.”
The authors suggest vehicular and human disturbances at the railway underpasses may have restricted their use by the elephants.
They cite evidence indicating that transient human settlements at the underpasses limited their effectiveness in enabling elephant movements.
But even the elephants that used the underpasses were found to significantly alter their movements.
For example, their average speed is reported to have increased significantly during the actual crossing when compared to before and after crossing.
Females in family groups moved faster than the lone bulls when using the underpasses, says the study led by Benson Okita-Ouma of Save the Elephants.
Females the team explains invest heavily in their offspring and are protective of family members.
“Thus, the railway is more of a perceived risk for females, and there is more of a need to cross the railway as quickly as possible to ensure safety to all the family members compared to males.”
Seventy-eight percent of elephant crossings, the study says occurred during the night with the highest frequency between sunset and midnight when trains stop running.
“The fast speeds and the nocturnal patterns are behavioural responses of elephants in risky landscapes or under stress,” says the study.
The team is calling for more collaboration between conservationists and infrastructure developers in projects that affect wildlife habitats.
“Inter-agency partnerships are requisites for enhancing the effectiveness of the underpasses and sustaining ecosystem connectivity.”
As a practical immediate measure, they want the relocation of all illegal human settlements that are around the underpasses.
By Gatonye Gathura