The Kea: a New Zealand problem/Chapter 9
CHAPTER IX.
THE KIDNEY THEORY.
How o’er the fascinating features flits
The genuine passions of the nether pit!
—Alfred Domett.
One of the most popular (yet, as I think, erroneous) statements about the Kea, is that the bird chooses the part of the sheep where the kidneys are situated, and then, burrowing into the living animal by means of its powerful mandibles, devours this delicacy.
Nearly every writer on the subject repeats the statement, and some even quote it as a proof of the Kea’s intelligence.
In his “History of New Zealand Birds,” Sir W. Buller quotes a letter from Mr. W. Chamberlain, of Harbourne Hall, Birmingham, who cited the statement as an indication of the parrot’s reasoning powers. He says:—“Consider for a moment the sequence of events and the extraordinary change of habit attributed to the parrot. Between 1865 and 1870 the Kea first comes in contact with the shepherd, and commences to steal his meat, with a marked preference for the kidneys. This is natural enough, and any other parrot with a tendency to animal food might do the same, and here the matter would ordinarily rest. The shepherds would protect their meat, and the parrots would return to their natural food. Not so with the Keas. Between five and six years later they found not only that kidneys are somewhere inside living sheep, but where abouts and the nearest point on the back from which to reach them.”
Mr. Chamberlain is quite right in his statement of the fact, but I think that his deductions are far from correct.
Dr. Alfred Russel Wallace quotes a similar misstatement in his book entitled “Darwinism;” for, after describing the methods of the Kea’s attack, he says:—“Since then it is stated that the bird actually burrows into the living sheep, eating its way down to the kidney, which forms its special delicacy.”
These incorrect statements were made possible by the loose way in which some of our writers have collected their evidence, and, in some cases, have made use of mere sheep station rumours.
It was Mr. C. C. Huddlestone who first disputed the statement, and said that the Kea attacked sheep for the kidney fat and the flesh.
This idea of Mr. Huddlestone’s is supported by the evidence sent to me by men who have seen many sheep killed and wounded by the Kea, for they all (with one exception) state that the kidney is not the special attraction, but that the meat and fat are the object of the bird’s desire.
The witness who was the one exception, in another part of his letter, writes as follows:—“I have shot many Keas by dead sheep, and they vomit fat;” so there seems to be evidence, even in this exception, that the bird ate the fat rather than the kidneys.
Of course, the Kea’s taste may have changed since its first attempt at sheep-killing; yet many witnesses, ranging back to some of the earliest, do not support the kidney theory. A shepherd, in a letter to me, says:—“I have not examined many sheep that have been killed by Keas, but in the ones that I have investigated I have always found the same result,—the fat eaten and the kidneys left. Of course, the kidneys have been found mauled, but they were not sufficiently torn to give the impression that the Keas had been eating them.”
Another correspondent says:—“I was walking quietly along and came to the edge of a slight depression in the ground, and there, right at my feet, a Kea rose from the body of a sheep. I examined the sheep. It was a fat merino wether,—perfectly sound; but it had been severely injured by the Kea. A hole had been made in the sheep’s loin,—the kidneys were protruding, and some of the fat had been eaten.”
Other correspondents write in a similar strain, stating that the kidneys were usually untouched and the fat eaten.
If the kidneys were the special delicacy, as “Darwinism” states, then the Keas, I am certain, would have devoured them as soon as they were exposed.
Whatever may have been the attraction in the early days, the Kea does not now kill sheep for the sake of the kidneys.
People have been led to suppose that the Kea always went for the kidney, because it always attacked the sheep just over these organs; but, after having gone through the accounts of about fifty eye-witnesses, I cannot find any trustworthy evidence in support of the kidney theory.
Without crediting the Kea with any special powers of reasoning, there are several better reasons that easily explain its procedure; and these show that the bird simply attacks in the easiest, most natural and most effective way. It is, I think, too much to assume that the Kea has inherited from its parents the knowledge as to where the sheep’s kidneys are situated; and yet from the first the rump has been the favourite part of attack. The shoulders are injured sometimes, but this is only in the case of sheep buried in the snow. Even if we assume that the Kea has intelligence enough to discover the position of the kidneys, we are still left with a difficulty. We are asked to believe that, within the last fifty years, or even a much shorter period, the acquired character of being able to locate the sheep’s kidneys has become an inherited character and is passed on to the offspring. In believing this we accept as a basis for agrument that which is a matter for keen controversy among our leading biologists, and is by no means decided. No good case can be built on such insecure foundation. We must look in some other direction for an explanation of the Kea’s habit.
If we look at the facts we shall see that the Kea injures the loin, not because the kidneys are there, but because it is the easiest and in some cases the only possible point of attack. Nearly all my correspondents say that, from what they have seen, the Kea with few exceptions always settles on the sheep’s hind-quarters.
The first reason for this is that the rump is the widest and most solid part of the sheep’s back, and so forms a firm platform for the bird to alight on. Some eye-witnesses say that it is the only place where a Kea can retain its hold on a sheep.
One states:—“It is almost impossible for a Kea to stick on a sheep’s back, while pecking it, in any other position than behind the kidneys facing the head. I have seen them trying to hang on to the sheep’s back, but unless they were in the position described they could not stay on for ten yards.”
A musterer, writing to me concerning Keas that had worried some sheep in a sheep-camp, says:—“They did not seem to follow the same sheep, but just hopped on to the first one they came to. Sometimes, when one got on a sheep’s back in a good position—behind the kidneys, facing the head,—it would keep pecking, and would keep the sheep jumping round and through the mob for a long time.”
Secondly, when the Kea flies after a sheep the rump is the nearest and handiest part to settle on, and, as the sheep often stumbles and throws the bird off, it will often have to regain its seat while the poor beast is running; so it is no wonder that this part is nearly always selected.
Thirdly, when the Kea is once perched on the sheep’s back, it will naturally begin to peck at the handiest part, and this is certainly the loin. Fortunately for the bird, that part is the least protected portion of the whole sheep, for the loins are the only places where the internal organs are unprotected by ribs or other bone. Thus the bird can easily tear its way into the body cavity.
There seems to be very little doubt that the preceding reasons do more to determine the Kea’s point of attack than the presence of the kidneys or kidney fat. Though the bird is fond of the kidney fat, I do not consider that there is enough evidence to show that this part of the beast is the main attraction.
This is supported by the fact that many cases are known of sheep-killing where the fat is untouched.
In July, 1907, I saw several sheep which had undoubtedly been killed by the Kea, and, though the muscles along the backbone had been torn off, the kidney fat was untouched.
The birds appear in many cases to eat whatever part comes first. Starting at the skin, they eat through the flesh, then on to the fat. Often the fat is only partially eaten, while the intestines have been pulled out and may be found dragging for some distance on the ground.
A correspondent states that one day he came suddenly upon two or three Keas pecking at the loin of what he supposed was a dead sheep. There was a hole in the sheep’s back, and the birds were putting their heads right through to the inside of the animal and pulling out portions of the intestines. He went over, and to his surprise found that the sheep was not dead: he killed it to put it out of pain.
It seems that the birds do not mind what part they eat when they are hungry, so long as they obtain a meal. Mr. Ewen Cameron, of Otago, gives the following instance:—“A snow-slip carried some sheep with it, and I found a sheep stuck in the snow, where it had landed, still alive, with its legs eaten to the bone, and half a dozen Keas tearing away at him.”
The evidence that has been received up to date definitely proves that the Kea does not kill the sheep for the sake of the kidneys only, and I doubt very much if they are in any way the source of attraction. As for the kidney fat being the coveted delicacy, there is some evidence to support it; but there is good reason to believe that mechanical reasons and not physiological ones determine the point of attack.
The case of the Kea is certainly unique in the fact that an insectivorous and fruit-eating parrot should develop the characteristics of a bird of prey. But, when we understand the reasons that led the bird to change its habit, much of the wonder ceases.
The stout grasping feet, made for holding on to rocks and trees, were naturally fitted for holding on to a sheep’s back; and the powerful beak, used for grubbing in the earth or tearing off the bark of trees, was admirably fitted for tearing off the flesh of sheep.
Therefore, being, as it were, naturally adapted for such attack, it is not so very strange that the Kea, having been forced into a new way of procuring food, soon developed into a bird of prey.
There is an interesting point mentioned by Professor Benham, in a paper on the Kea, published in the “Transactions of the New Zealand Institute, 1906.”
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Humerus of Sheep, said to have been split open by Keas.
Quoting from a correspondent’s paper he says:—“There is another matter I would like to point out to you about Keas; when they have eaten all the flesh off the bone then they tackle the shoulder (i.e., humerus) and leg bone and take all the marrow out of them by chipping them with their beaks until they obtain an entrance. I am sending you four shoulder bones, some old and some fresh ones killed last year.”
Professor Benham kindly gave me one of the bones, which I have here figured, and also lent me the correspondent’s letter.
I wrote letters to those men who might be able to give me information on this point, and even went so far as to ask for evidence through the newspapers which circulate through the Kea country, but I received nothing to support the suggestion made in the letter.
In order to ascertain on what authority the statement was made, I wrote to the correspondent and asked him to let me know if he had ever seen the Keas breaking the bones, and also if he could furnish the names of men who could give me authentic evidence on this very interesting point; but I received no answer.
Nowhere else in all the Kea country did I hear of any similar instance of bone-splitting by Keas, and therefore, until more conclusive evidence is forthcoming, the matter must be regarded as a supposition merely. I cannot trace any teeth marks on the bone; as the Kea has been known to split thin flakes from the soft rocks, it may, by commencing at the head of the bone, which is somewhat soft, be able to split a bone open.
It is certain from the appearance of the bone that some animal has split it open; but from the evidence to hand we cannot be sure that this was the work of the Kea.