The Defassa form has a solid white rump patch rather than the white ring of the common waterbuck. At Nechisar in southern Ethiopia, a 2016–17 study recorded mainly grazing, with more browsing in the dry season.
Silveira (2002) describes both male and female Defassa waterbuck as having a fully white rump patch, unlike the elliptical white ring of K. e. ellipsiprymnus. Intermediate rump patterns are reported in the Rift Valley overlap zone, so the patch does not identify every animal there.
A 2017 study in Nechisar National Park recorded 20 food plants and reported grazing as the main feeding mode overall. Browsing increased in the dry season. Animals were recorded using grassland, riverine forest, bushland and wetland.
An extinction-risk assessment has not been added yet.