Harmony and Conflict in the Living World - Alexander F. Skutch [21]
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Hunger and Fear as Causes of Hostility
The chief causes of conflict among animals are hunger and sexual rivalry. The need or inclination of each individual or closely knit group, in many species, to preserve for itself, and keep free from others of its kind, a territory or area that provides food or shelter or both is a secondary cause of conflict: the defended space would have little value if it failed to yield nourishment or to hold rivals aloof. On the whole, sexual rivalry is not a major cause of avoidance or fear among animals; much of the so-called sexual fighting, especially in birds, is formal jousting that rarely results in injury to either contestant. As a rule, the victor in these duels has no incentive to pursue his fleeing antagonist beyond his own domain; and when the season of resproduction has passed, the former rivals may gather in friendly groups once more. This leaves hunger as the great disruptive force in the animal world, the chief cause of fear. Because some animals need others as food, these others must defend themselves desperately or else flee for their lives. Unlike an animal withdrawing from a sexual rival, who is usually satisfied by the departure of his antagonist, the creature fleeing from a predator can satisfy its pursuer only with its living flesh.
Aside from humans and some of the social hymenoptera, animals rarely wage war or kill other animals except to fill their stomachs. When not hungry, predatory animals, including some of the fiercest, only exceptionally molest others, even of kinds on which they habitually prey. Antelopes and other herbivores are somehow able to recognize the moods or intentions of the carnivores that eat them, galloping away from hunting lions but continuing to graze peacefully in the vicinity of these hereditary enemies when the latter are not interested in prey. Similarly, ducks have been seen swimming about fearlessly while carnivorous otters played among them. Hawks that catch smaller birds often hunt chiefly at a distance from their nests, leaving unmolested small songbirds rearing broods beneath the eyrie. The birds learn which kinds of hawks are dangerous and which relatively innocuous, and they may sometimes be seen feeding calmly in the tree where one of the latter sort rests.
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Some animals instinctively avoid predators that have for generations preyed upon their kind, but they lack an innate tendency to shun other animals in general; so that they may remain unconcerned near one so potentially dangerous as man, until disastrous encounters, over a long interval, have taught a sort of wisdom to their race. Thus, it is well-known that birds and other creatures on uninhabited islands, or in other regions from which humans had long been absent, proved fearless of people, with the lamentable consequence that mariners who encountered them in their pristine innocence exterminated whole species before they acquired wariness, as happened to the Great Auk of Labrador and the Dodo of Mauritius.
Moreover, even among the predators themselves, the habit of capturing and tearing the prey appears in some instances to be not innate but learned from the example of parents or others of their kind. We learn from Lockwood Kipling's Beast and Man in India (1892) that the young Cheetah is not worth catching, for it has not learned to hunt and its human captors cannot teach it. Konrad Lorenz (1952), the famous student of animal behavior, owned a female Imperial Eagle, acquired after she was already mature. Even when hungry she refused to harm a