The only other things over which fighting is likely to arise are food and nesting sites.

It frequently happens that birds of different species want the same food. But this rarely leads to anything in the nature of a battle. In such contests the weaker almost invariably gives way to the stronger without any fighting.

A familiar instance of this is afforded by the behaviour of the white-backed (Pseudogyps bengalensis) and the black vultures (Otogyps calvus) when they gather round a carcase.

Jesse writes, and my experience bears out what he says: “Often I have been watching the vulgar white-backed herd, with a disreputable following of kites and crows, teasing and fighting over a body, when one of these aristocrats (i.e. Otogyps calvus), in his red cap and white waistcoat, has made his appearance. Way is immediately made for him, the plebeian herd slinking back as if ashamed or afraid, and I cannot remember the last comer ever being obliged to assert his authority.”

If the smaller vultures, which are the more numerous, chose to combine, they could drive off the black vultures, but in doing this some of them would run the risk of sustaining injuries. Now, it seems to be a rule in nature that no creature will willingly run such a risk. Rather than do this an animal will flee before a comparatively puny adversary.

The instinct of self-preservation, which includes the preservation of the body from injury, is strongly developed in all organisms. Natural selection tends to develop this instinct, because the individuals in which the instinct is strongly developed are less likely to be injured by fighting than those which are pugnacious. In other words, it does not pay to fight in nature. Injured individuals are seriously handicapped in the struggle for existence. Thus natural selection tends to produce cowards.

At the breeding season an instinct, which is ordinarily dormant in birds, suddenly becomes active—the instinct of preserving the nest and its contents.

This instinct, when aroused, frequently overmasters the instinct of self-preservation, with the result that shy birds become bold, timid ones grow aggressive, little birds which usually are terrified at the close proximity of a human being allow themselves to be handled rather than leave their eggs or young.

At the breeding season the desire to protect the nest leads many birds to attack, or to make as if to attack, all intruders.

No sight is commoner in India than that of a pair of little drongos (Dicrurus ater) chasing a kite or a crow.

Similarly I have witnessed doves chase and put to flight a tree-pie (Dendrocitta rufa), and fantail flycatchers mob a corby (Corvus macrorhynchus).

Nor are such cases confined to India.

In England Mr. A. H. Bryden states that he has seen sea-gulls mob and put to flight so formidable a creature as a peregrine falcon.

In each of the above instances the bird pursued could, if it wished, turn round and rend its puny adversaries. Why does it not do so? Because the instinct of self-preservation is implanted in it so firmly.

This instinct teaches it never to resist an attack, no matter how feeble the attacker be.

The object of the attack, provided it have no nest to defend, has everything to lose and nothing to gain by resisting the attack and giving battle. It matters little to a golden eagle on the look-out for quarry in which direction it flies; hence if, while it is sailing through the air, it is suddenly attacked by a couple of infuriated ravens, the obvious course is for it to change the direction of its flight. If it fail to do this it must either run the risk of being severely pecked by the ravens or fight them and thereby expose itself to injury. Under the circumstances it naturally chooses the line of least resistance.

It is absurd to speak of a bird that behaves in this manner as being defeated in battle. It does not suffer defeat. It merely declines to give battle.

The general rule in nature is, “Never fight when a fight can be avoided.”

This rule is unconsciously followed by all birds, except those that have nests.

The most familiar example of the rule in operation is the well-known habit of birds of surrendering their perches to new-comers. When individual A flies to a perch occupied by individual B the latter almost invariably gives way without demur. The particular perch is of no value to the occupier, but a whole body may be a matter of life or death.