Animal Intelligence Part 23

CHAPTER IX.

BATRACHIANS AND REPTILES.

ON the intelligence of frogs and toads very little has to be said. Frogs seem to have definite ideas of locality; for several of my correspondents inform me that they have known cases in which these animals, after having been removed for a distance of 200 or 300 yards from their habitual haunts, returned to them again and again. This, however, may I think perhaps be due to these haunts having a moistness which the animals are able to perceive at a great distance. But be this as it may, certainly the distance at which frogs are able to perceive moisture is surprising. Thus, for instance, Warden gives a case in which a pond containing a number of frogs dried up, and the frogs thereupon made straight for the nearest water, although this was at a distance of eight kilometres.[130]

A curious special instinct is met with in the toad _Bufo obstetricans_, from which it derives its name; for the male here performs the function of an accoucheur to the female, by severing from her body the gelatinous cord by which the ova are attached.

Another special instinct or habit manifested by toads is described by M.

d.u.c.h.emin in a paper before the Academy of Sciences at Paris.[131] The habit consists in the killing of carp by squatting on the head of the fish and forcing the fore-feet into its eyes. Probably this habit arises from s.e.xual excitement on the part of the toads.

I have one case, communicated to me by a correspondent, of a frog which learnt to know her voice, and to come when called. As fish will sometimes do the same thing, the account is sufficiently credible for me to quote:--

I used to open the gate in the railings round the pond, and call out 'Tommy' (the name I had given it), and the frog would jump out from the bushes, dive into the water, and swim across to me--get on my hand sometimes. When I called 'Tommy,' it would nearly always come, whatever the time of day, though it was only fed after breakfast; but it seemed quite tame.

A very similar case is recorded by Mr. Pennent[132] of a toad which was domesticated for thirty-six years, and knew all his friends.

There is no doubt that frogs are able to appreciate coming changes of weather, and to adapt their movements in antic.i.p.ation of them; but these facts show delicate sensibility rather than remarkable intelligence.

The following observation of Edward, the Scottish naturalist, however, shows considerable powers of observation on the part of frogs. After describing the great noise made by a number of frogs on a moonlight night, he says:--

Presently, when the whole of the vocalists had reached their highest notes, they became hushed in an instant.

I was amazed at this, and began to wonder at the sudden termination of the concert. But, looking about, I observed a brown owl drop down, with the silence of death, on to the top of a low d.y.k.e close by the orchestra.[133]

_Reptiles._

Like the other cold-blooded Vertebrata, the reptiles are characterised by a sluggishness and low development of mental power which is to some extent proverbial. Nevertheless, that some members of the cla.s.s present vivid emotions is not to be questioned. Thus, to quote from Thompson:--

The common guana (_Lacerta iguana_) is naturally extremely gentle and harmless. Its appearance, however, is much against it, especially when agitated by fear or anger. Its eyes then seem on fire; it hisses like a serpent, swells out the pouch under its throat, lashes about its long tail, erects the scales on its back, and extending its wide jaws, holds its head, covered over with tubercles, in a menacing att.i.tude. The male, during the spring of the year, exhibits great attachment towards the female. Throwing aside his usual gentleness of character, he defends her even with fury, attacking with undaunted courage every animal that seems inclined to injure her; and at this time, though his bite is by no means poisonous, he fastens so firmly, that it is necessary either to kill him or to beat him with great violence on the nose, in order to make him quit his hold.[134]

Several species of snake incubate their eggs and show parental affection for their young when they are hatched out; but neither in these nor in any other of their emotions do the reptiles appear to rise much above the level of fish. The case, however, which I shall afterwards quote, of the tame snakes kept by Mr. and Mrs. Mann, seems to show a somewhat higher degree of emotional development than could be pointed to as occurring in any lower Vertebrata. Moreover, according to Pliny, so much affection subsists between the male and female asp, that when the one is killed the other seeks to avenge its death; and this statement is so far confirmed--or rather, its origin explained--by Sir Emerson Tennent that he says when a cobra is killed, its mate is often found on the same spot a day or two afterwards.

Pa.s.sing on to the general intelligence of reptiles, we shall find that this also, although low as compared with the intelligence of birds and mammals, is conspicuously higher than that of fish or batrachians.

Taking first the case of special instincts, Mr. W. F. Barrett, in a letter to Mr. Darwin, bearing the date May 6, 1873, and contained among the MSS. already alluded to, gives an account of cutting open with a penknife the egg of an alligator just about to hatch. The young animal, although blind, 'instantly laid hold of the finger, and attempted to bite.' Similarly, Dr. Davy, in his 'Account of Ceylon,' gives an interesting observation of his own on a young crocodile, which he cut out of the egg, and which, as soon as it escaped, started off in a direct line for a neighbouring stream. Dr. Davy placed his stick before it to try to make the little animal deviate from its course; but it stoutly resisted the opposition, and raised itself into a posture of offence, just as an older animal would have done.

Humboldt made exactly the same observation with regard to young turtles, and he remarks that as the young normally quit the egg at night, they cannot see the water which they seek, and must therefore be guided to it by discerning the direction in which the air is most humid. He adds that experiments were made which consisted in putting the newly hatched animals into bags, carrying them to some distance from the sh.o.r.e, and liberating them with their tails turned towards the water. It was invariably found that the young animals immediately faced round, and took without hesitation the shortest way to the water.

Scarcely less remarkable than the instincts of the young turtles are those of the old ones. Their watchful timidity at the time of laying their eggs is thus described by Bates:--

Great precautions are obliged to be taken to avoid disturbing the sensitive turtles, who, previous to crawling ash.o.r.e to lay, a.s.semble in great shoals off the sand-bank. The men during this time take care not to show themselves, and warn off any fisherman who wishes to pa.s.s near the place. Their fires are made in a deep hollow near the borders of the forest, so that the smoke may not be visible. The pa.s.sage of a boat through the shallow waters where the animals are congregated, or the sight of a man or a fire on the sand-bank, would prevent the turtles from leaving the water that night to lay their eggs; and if the causes of alarm were repeated once or twice they would forsake the praia for some other quieter place... .

I rose from my hammock by daylight, shivering with cold--a praia, on account of the great radiation of heat in the night from the sand, being towards the dawn the coldest place that can be found in this climate. Cardozo and the men were already up watching the turtles. The sentinels had erected for this purpose a stage about fifty feet high, on a tall tree near their station, the ascent to which was by a roughly made ladder of woody lianas. They are enabled, by observing the turtles from this watch-tower, to ascertain the date of successive deposits of eggs, and thus guide the commandante in fixing the time for the general invitation to the Ega people. The turtles lay their eggs by night, leaving the water, when nothing disturbs them, in vast crowds, and crawling to the central and highest part of the praia. These places are, of course, the last to go under water when, in unusually wet seasons, the river rises before the eggs are hatched by the heat of the sand. One could almost believe, from this, that the animals used forethought in choosing a place; but it is simply one of those many instances in animals where unconscious habit has the same result as conscious prevision. The hours between midnight and dawn are the busiest. The turtles excavate with their broad webbed paws deep holes in the fine sand: the first comer, in each case, making a pit about three feet deep, laying its eggs (about 120 in number) and covering them with sand; the next making its deposit at the top of that of its predecessor, and so on until every pit is full. The whole body of turtles frequenting a praia does not finish laying in less than fourteen or fifteen days, even when there is no interruption. When all have done, the area (called by the Brazilians _taboleiro_) over which they have excavated is distinguishable from the rest of the praia only by signs of the sand having been a little disturbed.[135]

The same naturalist says of the alligator,

These little incidents show the timidity and cowardice (? prudence and caution) of the alligator. He never attacks man when his intended victim is on his guard; but he is cunning enough to know when this may be done with impunity. Of this we had proof a few days afterwards, &c.[136]

Of the alligator, Jesse writes:[137]--

But a most singular instance of attachment between two animals, whose natures and habits were most opposite, was related to me by a person on whose veracity I can place the greatest reliance. He had resided for nine years in the American States, where he superintended the execution of some extensive works for the American Government. One of these works consisted in the erection of a beacon in a swamp in one of the rivers, where he caught a young alligator. This animal he made so perfectly tame that it followed him about the house like a dog, scrambling up the stairs after him, and showing much affection and docility. Its great favourite, however, was a cat, and the friendship was mutual. When the cat was reposing herself before the fire (this was at New York), the alligator would lay himself down, place his head upon the cat, and in this att.i.tude go to sleep. If the cat was absent the alligator was restless; but he always appeared happy when the cat was near him. The only instance in which he showed any ferocity was in attacking a fox, which was tied up in the yard. Probably, however, the fox resented some playful advances which the other had made, and thus called forth the anger of the alligator. In attacking the fox he did not make use of his mouth, but beat him with so much severity with his tail, that, had not the chain which confined the fox broken, he would probably have killed him. The alligator was fed on raw flesh, and sometimes with milk, for which he showed a great fondness. In cold weather he was shut up in a box, with wool in it; but, having been forgotten one frosty night, he was found dead in the morning. This is not, I believe, a solitary instance of amphibia becoming tame, and showing a fondness for those who have been kind to them. Blumenbach mentions that crocodiles have been tamed; and two instances have occurred under my own observation of toads knowing their benefactors, and coming to meet them with considerable alacrity.

With regard to the higher intelligence of reptiles, I may quote the following instances.

Three or four different correspondents tell me of cases which they have themselves observed, of snakes and tortoises unmistakably distinguishing persons. In one of these cases the tortoise would come to the call of the favoured person, and when it came would manifest its affection by tapping the boot of this person with its mouth; 'but it would not answer anyone else.' A separation of some weeks did not affect the memory of this tortoise for his friend.[138]

The following interesting observation on the intelligence of snakes shows, not only that these animals are well able to distinguish persons, and that they remember their friends for a period of at least six weeks, but also that they possess an intensity of amiable emotion scarcely to be expected in this cla.s.s. Clearly the snakes in question were not only perfectly tame, but entertained a remarkable affection for those who tended and petted them. The facts were communicated to me by Mr. Walter Severn, the well-known artist, who was a friend of Mr. and Mrs. Mann, the gentleman and his wife to whom the snakes belonged. Mr. and Mrs.

Mann having got into trouble with their neighbours on account of the fear and dislike which their pets occasioned, legal proceedings were inst.i.tuted, and so the matter came before the public. Mr. Severn then wrote a letter to the _Times_, in order to show that the animals were harmless. From this letter the following is an extract:--

I happen to know the gentleman and lady against whom a complaint has been made because of the snakes they keep, and I should like to give a short account of my first visit to them.

Mr. M., after we had talked for a little time, asked if I had any fear of snakes; and after a timid 'No, not very,' from me, he produced out of a cupboard a large boa-constrictor, a python, and several small snakes, which at once made themselves at home on the writing-table among pens, ink, and books. I was at first a good deal startled, especially when the two large snakes coiled round and round my friend, and began to notice me with their bright eyes and forked tongues; but soon finding how tame they were, I ceased to feel frightened. After a short time Mr. M.

expressed a wish to call Mrs. M., and left me with the boa deposited on an arm-chair. I felt a little queer when the animal began gradually to come near, but the entrance of my host and hostess, followed by two charming little children, put me at my ease again.

After the first interchange of civilities, she and the children went at once to the boa, and, calling it by the most endearing names, allowed it to twine itself most gracefully round about them. I sat talking for a long time, lost in wonder at the picture before me.

Two beautiful little girls with their charming mother sat before me with a boa-constrictor (as thick round as a small tree) twining playfully round the lady's waist and neck, and forming a kind of turban round her head, expecting to be petted and made much of like a kitten. The children over and over again took its head in their hands and kissed its mouth, pushing aside its forked tongue in doing so. The animal seemed much pleased, but kept turning its head continually towards me with a curious gaze, until I allowed it to nestle its head for a moment up my sleeve. Nothing could be prettier than to see this splendid serpent coiled all round Mrs. M. while she moved about the room, and when she stood to pour out our coffee. He seemed to adjust his weight so nicely, and every coil with its beautiful marking was relieved by the black velvet dress of the lady. It was long before I could make up my mind to end the visit, and I returned soon after with a friend (a distinguished M.P.[139]), to see my snake-taming acquaintance again... .

These (the snakes) seemed very obedient, and remained in their cupboard when told to do so.

About a year ago Mr. and Mrs. M. were away for six weeks, and left the boa in charge of a keeper at the Zoo. The poor reptile moped, slept, and refused to be comforted, but when his master and mistress appeared he sprang upon them with delight, coiling himself round them, and showing every symptom of intense delight.[140]

The end of this python was remarkable and pathetic. Mr. Severn tells me that some years after he had published the above letter Mr. Mann was seized with an apoplectic fit. His wife, being the only other person in the house at the time, ran out to fetch a doctor. She was absent about ten minutes, and on returning found that the serpent during her absence had crawled upstairs from the room below into that where her husband was lying, and was stretched beside him dead. Such being the fact, we are left to speculate whether the double seizure of the man and the snake was a mere coincidence, or whether the sight of its stricken master, acting on the emotions of a possibly not healthy animal, precipitated its death. Looking to the extreme suddenness of the latter, as well as to the fact of the animal having pined so greatly for his friends while it was confined at the Zoological Gardens, I think the probability rather points to the death of the animal having been accelerated by emotional shock. But of course the question is an open one.

So much for the power of reptiles to establish such definite and complete a.s.sociations as are required for the recognition of persons--a.s.sociations, however, to which, as we have seen, frogs, and even insects may attain. As for other a.s.sociations, a correspondent writes to me:--

I believe tortoises are able to establish a definite a.s.sociation between particular colours on a flat surface and food. Only the day before reading your article on animal intelligence I noticed the endeavours of a small tortoise to eat the _yellow_ flowers of an inlaid writing-table, and I have often remarked the same recognition with regard to red.

Lord Monboddo relates the following anecdote of a serpent:--

I am well informed of a tame serpent in the East Indies, which belonged to the late Dr. Vigot, and was kept by him in the suburbs of Madras. This serpent was taken by the French, when they invested Madras in the late war, and was carried to Pondicherry in a close carriage. But from thence he found his way back again to his old quarters, which it seems he liked better, though Madras is distant from Pondicherry about one hundred miles. This information, he adds, I have from a lady who then was in India, and had seen the serpent often before his journey and after his return.

Considering the enormous distances over which turtles are able to find their way in the season of migration, this display of the homing faculty to so great a degree in a serpent is not to be regarded as incredible.

Mr. E. L. Layard, in his 'Rambles in Ceylon' says of the cobra:[141]--

I once watched one which had thrust its head through a narrow aperture and swallowed one (_i.e._ a toad).

With this enc.u.mbrance he could not withdraw himself.

Finding this, he reluctantly disgorged the precious morsel, which began to move off. This was too much for snake philosophy to bear, and the toad was again seized; and again, after violent efforts to escape, was the snake compelled to part with it. This time, however, a lesson had been learnt, and the toad was seized by one leg, withdrawn, and then swallowed in triumph.

Mr. E. C. Buck, B.C.S., says in 'Nature' (vol. viii., p. 303):--

I have witnessed exactly a similar plan pursued by a large number of Ganges crocodiles, which had been lying or swimming about all day in front of my tent, at the mouth of a small stream which led from some large inland lakes to the Ganges. Towards dusk, at the same moment every one of them left the bank on which they were lying, or the deep water in which they were swimming, and formed a line across the stream, which was about twenty yards wide. They had to form a double line, as there was not room for all in a single line.

They then swam slowly up the shallow stream, driving the fish before them, and I saw two or three fish caught before they disappeared.

An account of reptile psychology would be incomplete without some reference to the alleged facts of snakes charming other animals by 'fascination,' and being themselves charmed by the arts of music, &c.

The testimony on both subjects is conflicting, and especially with regard to the fascination of other animals by snakes. Thus:--