Historia Animalium 608b19
"Now there is a war against each other among all animals that occupy the same places and get their living from the same things. for if their food is scarce, even those of the same breed fight against each other, for they say that even the seals living around the same place make war, male against male and female against female, until one kills the other or is driven away; and the pups all do the same. Further, all are at war with the carnivores, and they with the others; for they feed on the animals. It is from this that the diviners get their dissociations and associations, classing as dissociates those that are at war and as associates those that are a peace with each other. But if there were no shortage of food, those that are now frightened and grow wild would probably behave tamely both towards humans and in the same way towards each other. This is made clear by the way animals are looked after in Egypt; for because food is available and they are not in want, even the wildest animals live with each other; for they become tame because of the benefits given to them, for example in some places the crocodile kind has become tame towards the priest because their food is looked after. The same things is to be seen occurring around the other countries too, and region by region within them."