Classical and secondary conditioning which must be designed to be species specific. It is far easier to train with stimuli that induce natural reflexes and work from the motivations of natural drives. You need to reliably provide the right enclosures, shelter, safety, food and water for a period of time to allow the animal to get used to you and realise that you're not a threat.
The method is different depending on the age of the animal and, if still a baby, whether the mother is already domesticated. Young can be imprinted at birth. The younger the animal the quicker the process of adaptation.
For an excellent example, check out YouTube: Monty Roberts explains Join-Up® with Equus, the horse.
Although the horse in the film is already somewhat domesticated, I've seen Monty do exactly the same with a fully mature mustang, and achieve saddling, bridling, and first rider in an average of 27 minutes every time.
SavvyAnsley 