Lumps & Bumps In The Nairobi National Park Over some years, I have noted that there seem to be more animals with abnormal growths in the Nairobi National Park than I have seen in other national parks, especially considering that the park is only 117sq km. Some time ago I began to notice a particularly big impala ram with long horns near the main gate. He was quite easy to see, due to a habit of standing next to the tar road and eating the greener grass caused by rainwater running off the road. At first, I noticed that the ram had a small round lump on its back, then over time, the lump began to grow until it was quite large. Eventually, the Impala seemed quite irritated, as he began to rub and scratch against tree branches and rocks until there was a bare hairless patch around the lump.