Keeping together in such numbers makes great demands on the pasture and the herds have migrate regularly over great areas. Wildebeest (Connochaetes taurinus) seem able to detect a shower of rain falling as far away as 50 kilometres and will move off to find it and crop the newly sprouting grass. But this nomadic existence complicates the social arrangements for breeding that in the forest, based on a single pair, had been so simple. For some - the Impala (Aepyceros melampus), Springbok (Antidorcas marsupialis) and Kudus (Tragelaphus strepsiceros):- territory remains nonetheless the basis of their arrangements. Males and females form separate herds. A few dominant bucks leave the bachelor herd to establish individual territories for themselves. Each marks the boundary of its land, defends it against other males and tries to attract females into it and mate with them. This however is a demanding business and most of the bucks who undertake it are exhausted and badly out of condition after three months or so. Eventually, they are then forced to yield to stronger, more rested rivals and they go back to join the bachelor herd.
The eland (Taurotragus oryx), the largest of the antelopes, and the plainszebra are among the few that have finally broken the bond with territoriality altogether. They form herds in which both sexes are always present and the males settle their problems over females by battling between themselves wherever the herd happens to be.