The crater carries a resident population that does not migrate, so the wildebeest are simply always here, spread across the floor in the numbers the walls will hold. I worked this herd the way you work any big group: wide for the scale, then in tight for the animals.
The pool sets the scene, sky caught in the water with the herd around its edge. The wide frame gives you the count, small shapes strung across the plain. Then the tight one, the animals filling the frame with the dust coming up under them, and a black and white in the middle because the whole thing was already halfway to monochrome in the haze.
All on the 135 at base ISO 64. One herd, four frames, the standard argument that a subject is worth photographing at more than one distance.