Topi of Boma National Park

VERY FALL THE PLAINS OF South Sudan, normally pale yellow and brown, turn a vibrant viridescent shade. This explosion of greenery helps spur on one of the largest mammal migration in the world. Every October, at least a million antelope thunder across the plains towards the vast lowlands around the White Nile. An estimated 125,000 of the migration’s participants are the spectacularly weird topi.

With an estimated 300,000 spread throughout sub-Saharan Africa, the topi migrating through South Sudan number a little less than half the entire population. These medium-sized antelopes are a deep, burnish brown with black splashes across their foreheads, thighs, and hips. They also sport light tan “socks” allowing their legs to blend into the tall grassy plains they call home.