3.1

Surveys have reported steep declines (60-70%) over periods of c. 20 years dating from the late 1970s in several places, including the main strongholds for the species: Serengeti, Masai Mara and Ngorongoro. Though overall numbers still seem to be falling, no declines on this scale have been reported recently. However, it is estimated that the decline over the last 3 generations (18 years) has reached 25%, and is very possibly higher, bringing the species very close to qualifying for Vulnerable under criterion A. Careful monitoring of population trends is needed and it is entirely feasible that new survey information could merit transfer of this species to a higher category of threat. This assessment considers E. thomsonii and E. mongalla as separate species when formerly they were assessed together. Under this arrangement, Thomson's Gazelle now has a relatively restricted distribution within East Africa, which should also be taken into consideration.