I posted this shot of zebra and wildbeest (gnu) gathering together in preparation for the great migration - or rather the return journey from the Serengeti to the Massai Mara - because I learned this trip why they always travel together and I found it fascinating: Firstly although they both eat the same grass, zebra have large teeth and are able to eat the long grass, while wildebeest feed on the shorter grass, so they do not compete on food; but more importantly the zebra have very good eyesight and can see much better and while having very good memories they are therefore able to remember the route, while the wildebeest have a much better sense of hearing to protect against preditors and a better sense of smell which enables the group to find water. So now you know! :) I took this photo in the Serengeti National Park in Tanzania