Exploring Nairobi National Park, I added check boxes next to details that I need to look at the next time I see some of these birds- when the sketch does not match the field guide, sometimes the sketch does not match the bird and sometimes the field guide is off. The answer is in the bird. Whistling thorn Acacia is a really interesting plant. It has swollen thorns that house ants that give it extra protection. Shake the bush and out come the ants!