These clumsy clowns of the wild, with their humped shoulders, sloping backs and rocking-horse gait may justifiably snort and grunt in alarm, toss their massive heads about nervously and search the air for scents of predators: being the favourite prey of lions they have to be ever on the alert. They are gregarious, and occur in herds of 20 to 30 individuals; they may also form much larger herds numbering thousands. Like the black wildebeest, their social organization consists of territorial males, female herds, and bachelor groups. On their massive migrations, the younger, non-territorial bulls travel at the perimeter of the herd, often relying on the timidity of accompanying zebra for an early warning if predators are about. Exceptionally inquisitive, blue wildebeest often stand and stare at an intruder, before suddenly whirling round and galloping off. Blue wildebeest are tough and although normally timid, will fight ferociously when cornered. A single calf is born, usually between December and January. The young stay close to their mothers, who will suckle only their own calf