The most celebrated breaker of shells is the Bearded Vulture or Lammergeyer (Gypäetos barbatus). This rapacious bird is very common in Greece, where he does not usually live on large prey. If he sometimes carries away a fowl, it is exceptional; he prefers to live on carrion or bones, the remains of the feasts of man or of the true vulture. He rises very high carrying these bones in his talons and allows them to fall on a stone, swallowing the fragments after having sucked out the marrow. He is also greedy of tortoises, and uses the same method to break their carapaces, eating the soft parts. These facts have been many times observed by Brehm and other trustworthy naturalists. It is even said that in Greece every Lammergeyer chooses a rock on which he always comes to execute the tortoises he has captured. It was no doubt beneath one of these birds so occupied that, according to the story, mischance conducted Æschylus.
Neither the beak nor the claws of the Shrike or Butcher-bird (Lanius excubitor) are strong enough to enable him to tear his prey easily. When he is not too driven by hunger he installs himself in a comfortable fashion for this carving process, places on a thorn or on a pointed branch the victim he has made, and when it is thus fixed easily devours it in threads.
The Lanius collurio, an allied bird, uses this method still more frequently. He even prepares a small larder before feasting. One may thus see on a thorny branch spitted side by side Coleoptera, crickets, grasshoppers, frogs, and even young birds, which he has seized when they were in flight.[28] ([Fig. 6.])
Of all these well-attested facts that which perhaps best shows how animals in certain circumstances may take advantage of a foreign body to utilise the product of the chase, is the following, the observation of which is due to Parseval-Deschênes.[29] He followed during several hours an ant bearing a heavy burden. On arriving at the foot of a little hillock the animal was unable to mount with his load, and abandoned it — a very extraordinary fact for one who knows the inconceivable tenacity of insects. The abandonment therefore left hope of return. The ant at last met one of his companions, who was also carrying a burden. They stopped, took counsel for an instant, bringing their antennæ together, and started for the hillock. The second ant then left his burden, and both together then seized a twig and introduced its end beneath the first load which had been abandoned because of its weight. By acting on the free extremity of the twig they were able to use it exactly as a lever, and succeeded almost without trouble in passing their booty on to the other side of the little hillock. It seems to me that these ants who invented the lever are worthy of admiration, and that their ingenuity does not yield to our own.
I will, finally, give an example of the methods of surmounting a difficulty of another order in utilising captured prey. It is not enough to capture prey, or even to possess the means of utilising the prey when captured. It is sometimes also necessary to prevent the booty being taken possession of by some other member of the same species as the hunter. Spiders are specially liable to this danger, because their victims are noisy when caught. Hudson has described an ingenious device made use of by a species of Pholcus — a quiet inoffensive Spider found in Buenos Ayres — to escape this risk. This spider, though large, is a weak creature, and possesses little venom to despatch a fly quickly. The task of killing it is therefore long and laborious, and the loud outcries of the victim may be heard for a long time, sometimes for ten or twelve minutes. The other spiders in the vicinity are naturally excited by this noise, and hurry out from their webs to the scene of conflict, and the strongest or most daring sometimes succeeds in carrying away the fly from its rightful captor. Where, however, a large colony have been long in undisturbed possession of a ceiling, when one has caught a fly he rapidly throws a covering of web over it, cuts it away, and drops it down to hang suspended by a line at a distance of two or three feet from the ceiling. The other spiders arrive on the scene, but not finding the cause of the disturbance retire to their own webs again. When the coast is thus clear, our spider proceeds to draw up the captive fly, now exhausted by its struggles.[30]
War and brigandage. — When Man attacks animals of another species, either to kill them and feed on their flesh, or to steal the provisions which they have amassed for themselves or their young, this is called “hunting,” and is considered as perfectly legitimate. When men turn to beings of their own species either to kill them or to rob them, several different cases are distinguished. If the assailants are few in number, it is called “brigandage,” and is altogether reprehensible; but if both assailant and assailed are considerable in number, the action is called “war,” and receives no reprobation.
There are hunters among animals as well as among ourselves, and we have seen their various methods of procedure; but there are also brigands and warriors, and our superiority even in this department is not so absolute as might be imagined.
Independently of ordinary brigandage, which is a brutal and simple form of the struggle for life, manifested every time the animals find themselves before a single repast, there are interesting facts to be noted concerning robbers who act in a manner that Man himself would not disavow. It is worthy of remark that it is the most sociable animals who furnish us with the most characteristic examples.