[5] In the early 20th century, this species had a relatively small distribution in northern Tanzania and southern Kenya.

The species' range in Tanzania had also continued to contract over the past 2 decades, and by 2021 it was restricted to the western Serengeti region.

[3] E. baumstarki is one of two known species of Erythrocebus with a black face and nose, at least in adult males, with the other being the Blue Nile patas monkey (E.

[4] E. baumstarki was likely never a common species; although it is difficult to observe, its core range is heavily visited by tourists and naturalists, and the very few historic specimens indicate that it was likely already rare when it was described in 1905.

Erythrocebus species depend on permanent sources of drinking water, especially after the increasingly frequent periods of drought; however, many of these water sources have herders present all day long, putting the monkeys into conflict with herders and domestic dogs, who may kill monkeys.

[3] Climate change may also be a potential threat due to it spurring a decrease in water availability and V. drepanolobium inhabiting specific altitudes that may decrease with warming, although its impact may be limited as patas monkeys have shown potential to adapt; due to this, human interactions likely serve as the greater threat to the species, and may magnify the effects climate change has on the species.

[3] Aside from Miss Waldron's red colobus (Piliocolobus waldronae) and the Mount Kenya potto (Perodicticus ibeanus stockleyi), both of which may be potentially extinct already, the southern patas monkey could be the most endangered primate in Africa, and may potentially be the next to go extinct.