SOME OBSERVATIONS ON SNAKES

動

物

心

理

第4卷

第1號 

昭 和 13年 6月

研

究

SOME OBSERVATIONS

ON SNAKES

RYOTA TA KATSUKI

Psychological Institute, Keijo Imperial University.

( 1 ). On the behavior of a snake, Elaphe schrenckii (STRAUCH),

and a new device for its terrarium.

The animal was 157cm. long and weighed 1010gr ; the observations

here reported were begun on June 26 and ended on July 9, 19 7, in

the outdoor snake terrarium of the Psychological Institute of the

Im-perial University of Keijo.

The diagram of the terrarium is

illustrated below.

Fig . 1

Fig . 2

Fig . 3 1

2 RYOTA TAIZATSUKI

The real size of each part in fig. I is as follows : ab : be : cd : de :

ea = 260 : 345 : 175: 90 : 316cm. The numerals in figs. 2 and 3 should

also be read in cm. The walls are made of zinc-sheet and as high as

135cm. , their top being crooked down inward by 15cm. as shown in

fig. 2 (b) to prevent the animal from climbing over it. At the

north-western corner and 11cm. above the ground, there is an entrance door, D, 65 •~ 122cm. , as shown in fig. 2 (a) ; its surface also made of

zinc-sheet is set three centimeters back from that of the wall, A brass

catch is equipped 70cm. above the lower edge of the door •kfigs. 2 (a)

and 3•l it is 10cm. long and 4cm. apart from the wall end, but on

July 2 it was removed to a new position x as illustrated in fig. 3. P is a pond 153 x 92 x 64 and its depth of water was only 2cm. at the

time of observation.

June 26. Fine. A little alteration was given to the terrarium

formerly used for tortoises and I put into it about _{. 1 o'clock in the}

afternoon the snake above mentioned together with some smaller ones

belonging to Elaphe rufodorsata and Natrix tigrina lateralis. It made

an escape from it between 3.00 and 4.00 p.m. but it was found soon on

a cherry-tree about 50cm. south-west of the terrarium and in the

adja-cent hen-house the roof of which made of the wire net was 55cm.

higher than the top of its wall. The branches of the tree covered the

wire roof of the hen-house and, therefore, the animal could easily go

from the the top of the wall to the tree clibming over the roof. It

was taken down and shut up in a feeding box in the laboratory.

June 29. Fine after rain. Seeing that the animal was fled into

the pond of the terrarium at 12.40 p. m. the author inspected it

stealthily from the laboratory window. The sky cleared up at about

1.30. It began to move at 1.35 and landed 5 minutes later from the southwest corner of the pond, there being a stepstone for tortoises to

crawl up. It soon hid under a strawmat and never appeared. At 4.00

it was driven by the author out of the mat with a long stick stretched out from the window. It went along the wall to the northwestern

cor-ner and tried in vain to climb up though it could stanl straight

al-most as high as 100cm. against the right-angled walls. Between 5.30 and

Some Observations on Snakes 3

6.30 when he was absent for his supper, it again took to flight and was found to be on the cherry-tree.. It. was immediately replaced in the terrarium. A 100 watt electric bulb was furnished in the north-western corner about 100 centimeters above the ground and the obser-vation was continued. It commenced to creep at 8.15 exploring along the wall and at last succeeded to thrust itself between the catch of the

door and the wall ; at 8.40 after a skillful climbing-up struggle for about 5 minutes using its tail most effectively (plates 1 and 2), its head reached the top of the bending edge of the wall and soon lifted half of its body over the wall. Again it was placed down at once into the terrarium. Since it seemed a little tired and could not move until 12.40 a.m. of the next day (30th), it was 'confined in a small box placed in it,

July 1. Fine. At 6.00 p.m. the animal was set free from the box. It did not move for a long time. At 9.40 it succeeded to run away from the same place by just the same means as before. It was put down at once. Hiding under the mat, it never came out. Though it was driven out, it remained quite motionless. It succeeded a third time

Plate 1 Plate 2

4 RYOTA TAKATSUKI

at 1.30 a.m. (July 2) in a similar manner. Its body posture is indicat-ed in plates 1 and 2, the latter showing the pose which was seen at about one minute's lapse after the former. It was then shut up like-wise as before in the box.

July 2. The catch on the door was removed to a new place x as illustrated in fig. 3 in order to make it unable for the animal to climb up along the wall, the space between the catch and the edge of the wall being changed from 4 cm. to 9 cm. It was set free from the box at 3.00 p.m. Betraying the supposition of the observer, it escaped clev-erly between 5.00 and 8.00 p.m. and absolutely no route of flight could be traced anywhere.

July 4. In the morning it showered very hard, but in the after-noon it cleared up. About 4.00 p.m. the observer out near the terra-rium met with Mr. SAI TO ZYU, a school guard, on his round of inspection and told how the animal escaped from the fence on July 2. Then all at once Mr. SAI noticed that a Chinese magpie was cawing in a low cherry-tree near a pile of the newly cut branches of a plane-tree about 30 feet to the south of the terrarium and that sparrows

were also chirping in crowds near it. He at once said intuitively that the snake must be near that tree. The observer drew nearer doubting

at first but astonished at fiuding th3 missing snake in safety on the pile of the branches. It had often previously been observed that a crowd of sparrows flew away from the terrarium. It was captured after an absence of about 24 hours and again was shut up in a feeding box in the laboratory.

July 9. Fine. The animal was -Liken into the terrarium at 9.20 in the morning. As it lay still in the shade of the wall, it woe forced to crawl about with a stick at 9.30. It went along the wall first to the west, then to the north, and at last to the east, It began to climb up the door as usual supporting itself in such a way as shown in fig. 4. on a catch removed and succeeded to place the bead on the top of the wall at 9.88, being, however, soon after put down. It started to climb up again at 9.40 in another way illustrated in fig. 5.

It lifted its body by degrees pushing itself earnestly on the

Some Observations on Snakes 5

crete margin of the pond and at length succeeded to get away at 9.55. From these o servations, it could probably be supposed that the animal had run away by the same method as above stated on July 2, too. Such being the case, the catch was then transferred to the middle of the upper end of the door as was shown as x' in fig,. 4 and the obser-vation was continued. The animal tried bard to climb up several times in succession at the door first and then at some corners, but all was of no use.

GENERAL CONCLUSIONS.

1). The snake, Elaphe schrenckii, has an apparent tendency of learning.

2). Some biological connections could be supposed between the snake and the Chinese magpie or sparrows.

3). a. An ideal outdoor snake terrarium should be made round or oval with a perpendicular, thoroughly even wall made of the zinc-sheet or painted board.

b. The terrarium with right-angled corners which was for-merly used for tortoises is not at all suitable, for they supply cues to escape by supporting the body against two walls when they are not

Fig. 4 Fig. 5

6 RYOTA PAKATSUKI

quite high.

c.

The entrance door and the wall must be almost on the

same plane.

d.

The height of the wall must at least be the same or

almost five-sixths of the whole length of the animal in accordance to

the absence or presence of the crooked top, but a lower wall will

suf-fice when the fence is made round.

e.

As the terrarium becomes very hot in the daytime when

the summer sun is shining, it needs must be vast enough with a water

pool and grass or weeds in it.

f.

Some trees which give comfortable shades all or partly

over it in the neighbourhood are also desirable.

g.

Some hiding places for snakes are necessary to be

con-structed.

(2). Snakes and frogs in the same terrarium.

July 9. Cloudy. At 7.30 p.m. two Bombina orientalis, four Rana

nigromacalata, and a Bufo bufo asiatieus were put in the terrarium

together with an Elaphe sehrenekii (STRAUCH), an Elaphe rulodorsata

(CANTOR), and six Natrix tigrina lateralis (BERTHOLD) to examine

the behavior both of snakes and frogs. To facilita4e the observation, a

bamhoo-cage and a strawm at were taken out of the terrarium, and the

observer found a Bombina orientalis put there a few days ago at that

time, thus there were three Bombina orienialis in all. No sooner than

a Bombina

jumped, a Natri.), bit at it and tried to swallow it, but

after a struggle of 13.5 minutes he at length brought it out of his

mouth. Another Natrix tried once to bite at the hip o1.)

a Bufo but it

soon retraced turning away. Just when it was made to place the bitten

Bonibina into the water of the pond w:th a stick, the frog was bit

after only a jump by an Elaphe rufo.

The snake coiled its long body

up on the frog, but stopped biting after about 12.5 minutes. At 8.10

a Natrix tried an attack on another Bo bina without biting and the

frog itself lay motionless from fear. At 8.15 it began to rain a little.

The Bufowas forced to move by the observer and two Natrix made

an attack at once but soon turned back slowly. The Bufo lifted its

Some Observations

on Snakes

7

back high straightening its hind legs, drooped its head down, and

showed a queer attitude of restraint. At 8.25, and 8.30 again the

Elaphe rufo. bit at a leg of its captured animal. At 8.42 a Rana was

caught by a Natrix. After a struggle for a prey between two Natrrx,

it was swallowed at 8.56 by a larger one. At 8.45 the Elaphe rufo.

at length swallowed up the poor Rombina. At 9.29 a Natrix bit at a

Bombina, swallowed it after two minutes but brought out again at

10.00. The frog jumped away, while the snake opened its mouth wide-

ly and twsted its body in seeming distress. Another Natrix overtook

this frog but never tried to bite. Until 11.00 p.m. there was no

acci-dent, and the frogs caught by the snakes during these four and a half

hours were only two. The animals left living were two Bombina, three

Rana and a Bufo.

July 10. Fine. Exploring all over the terrarium at 1.00 p.m,

I found that one Bombina, one Bana, and a Bafo remained alive. It

was the same at 4.00 p.m.

July 11. Fine. Only one Bufo was found at 1.00 p.m.

July 12. Fine. A new Bufo was taken into the terrarium. There

were two in all.

July 13. Fine. Two animals were found in safety.

July 14. Fine. There was no change at all.

GENERAL

CONCLUSIONS.

1). In the Elaphe schrenckii it was never seen that he tries to

catch the frog, as was already pointed out by Mr. HIRONOBU DOI.

(Thin, 1934, No. 3, p. 23).

2). Within observations here done, the Natrix can not eat the

Bombina, but the Elaphe rufo.

apparently can ; and two Bombina lost

afterwards would have perhaps been eaten by this snake.

3). Korean tradition says that the Bombina has s inc severe poison,

and the fact above mentioned suggests some different mechanism in the

Nctrix and the Elvphe rufo.

4). The Elaphe rafo, alone coils its body when a prey is caught.

5). All the ,snakes here stated dare not at all to attack the Bubo.

6). It was found accidentally that the Elaphe rufo and the

Natrix can eat loaches lying alive or half dead on the gr and.