New research finds that giraffes much prefer flat terrain and do not traverse slopes of more than 20°, which severely limits the areas in, and outside, protected reserves they can access. The findings, which is are yet to be published, will be presented at the British Ecological Society's (BES) Annual meeting in Liverpool on the 13th December.
A new study analysing the movements of 33 GPS collared giraffes in South Africa has found that they avoid steep terrain and are unable to navigate slopes with a gradient of more than 20° , most likely due to the energy required and the risk of falling.
The researchers from the University of Manchester and the University of the Free State, South Africa found that giraffes will tolerate terrain of up to 12°, but only if it leads to favourable vegetation.
Jessica Granweiler, a PHD candidate at the University of Manchester, who will present this research at the BES Annual Meeting said "We often think of giraffes roaming in large, flat grassland savannas in Africa, but that's not really their true habitat, there are also rolling hills, deep riverbeds and high plateaus.
"Our study shows that giraffes much prefer flat areas. They will tolerate some steepness to access food, but simply cannot access areas above a 20° gradient. It's quite shocking when you look at distribution maps."
"Giraffes are tolerant animals and resilient to many things like food availability and human pressures, but this is a scenario where they simply may not be able to adapt due to physiological limits."
The findings highlight a mismatch between the ideal, flat habitats of giraffes and the areas they're being conserved in. Using the newly discovered 20° gradient threshold, the researchers were able to calculate the proportion of habitats in key African countries where giraffes are currently found that are inaccessible to the animals.
"In Namibia and Tanzania, there is approximately 8,000km2 that may be unusable to giraffes, that's nearly half of the size of Wales." said Jessica. "In Kenya and South Africa, there's approximately 4,000km2 that may be unusable. What's even more worrying is that of all the countries we mapped, one in three had more unusable areas in protected areas than outside of protected areas."
This issue is exacerbated when reserves are fenced, which many in South Africa are. "If a reserve is say 200 hectares but has a large mountain in the middle, from a giraffe's perspective, this reserve is not 200 hectares anymore." said Jessica. "We need to start including topography in giraffe conservation planning and habitat assessments, especially for small fenced reserves."
