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Authors: S.MISHIMA, V. SAWAI, S.YAMASATO and R. SAWAI

Introduction

Observation on copulation, egg laying and hatching of an albino population of Elaphe climacophora the Japanese Ratsnake - considered to be a national Monument in Japan.

The Japanese Rat Snake (Elaphe climacophora) is endemic to Japan, occurring on all four of the islands which make up the country. It is considered a common snake, often living close to human habitation.

FOREWARD

Normal colouration is a mottled olive green to greyish, often with blotches or indistinct stripes. Juveniles resemble the adults, but are normally more brightly coloured with more attractive markings. Change to the adult colouration can take considerable time.


The snakes are very slow to mature, often not mating until they are four years of age, and are thought to live to at least 15 years. Maximum size is 1.7 metres (67inches), but most individuals do not attain this.


The species is of particular note in that a population of albino animals exists in the wild near Iwakuni City. This snake is known locally as The Shirohebi. The population is strictly protected and regarded as a Japanese Natural Monument.


INTRODUCTION

A study on captive breeding of the Shirohebi was entrusted to Japan Snake Institute by Iwakuni City. This report is concerned with copulation, egg-laying and hatching by eight adult snakes (three males and five females) transferred to the institute from a snake pit in Iwakuni City for an investigation of skin diseases which had appeared among
them

COPULATION

The copulation was seen between three couples on May 19th and two couples on May 21st, these dates of copulation being the same as for Elaphe climacophora. It was elucidated that the copulation could be repeated two or more times during the mating season, with a duration of each mating estimated at from two to five hours. Corting behaviour seemed more active in males than females.

EGG LAYING

The eggs were laid on 25th June, 4th, 6th and 11th of July 1973 Body length of the egg-laying females reached from 1,470mm to 1,880mm. The egg-laying started early in the morning and finished at 11am and 3pm respectively.

The duration of egg-laying was estimated at in excess of five hours. Total number of eggs was fifty seven (from nine to fourteen per snake)

Days from copulation to egg-laying ranged from 37 to 51 days and average size of the eggs was 52.2 +1- 3.00mm length and 26.0 + 0.6mm width.

HATCHING

A total of 51 glass vessels with plastic covers with many holes for ventilation were used for incubating the eggs. A type of moist water moss was placed in the vessels as an incubating medium and the temperature was kept at 26C. The eggs hatched at between sixty-one and sixty-five days.
Forty-eight eggs out of the total fifty-seven hatched successfully, whilst nine eggs died during incubation.

NEONATES

The hatchlings had all been observed to slough after one week. the average size of the neonates was 434mm + in length and 16.5mm +I-2.4g in weight.

Table 1: Summary of dates of copulation, egg-laying and hatching of Elaphe Climacophora.
No. Pair Date Pair Copulation Date / Time since paired Egg Laying / Time since copulation Hatching Date & Incubation
1 May 16th May 19th
3 Days
June 25th
37 Days
August 27th
63 Days
2 May 19th May 19th
20 Minutes
July 4th
46 Days
September 3rd
61 Days
3 May 19th May 19th
1.5 Hours
July 6th
46 Days
September 5th - 6th
61 - 62 Days
4 May 20th May 21st
1 Day
July 6th
46 Days
September 9th
65 Days
5 May 20th May 21st
1 Day
July 11th
51 Days
September 10th
61 Days
      Mean 45.6 Days Mean 62.2 Days

 

The egg tooth of this hatchling Shirohebi is clearly visible
Hatching of baby Shirohebi. The Juveniles are pinkish in colour compared to adult snakes

 

Table 2: Hatchling Rate for Elaphe climacophora
Number Laid Number Hatched Hatching Rate %
13 6 46.2
14 14 100
9 9 100
10 10 100
11 8 72.3


Table 3: Measurements of parental snakes (where such data was available).
Paental Snake # Sex Total Length (mm) Tail Length (mm) Body Weight (gr)
1 Female 1590 280 770
2 Male 1690 365 840
3 Female 1865 285 (incomplete) 1100
4 Female 1535 305 630
5 Female 1680 270 950
6 Male 1605 335 870


Table 4: Range of measurement of new-born snakes
Mother Snake No. Age in Days Total Length (mm Tail Length (mm) Body Weight (gr)
2 19 390-428 78-88 12.7-13.9
5 12 426-448 86-94 14.1-16.9
3 9-10 415-443 85-95 15.7-18.1
7 6 439-459 88-96 19.2-21.0
6 5 419-437 86-92 14.1-16.1


Table 5: Survival rate of baby snakes bred in wann room (note: survival rate for first three months was 100% and all then survived for at least two years following this report).
Mother Snake No. Survival Rate December January Febuary March April
2 No.
Survival %
6
100
5
83.3
4
66.7
3
50.0
2
33.3
5 No.
Survival %
14
100
13
92.7
10
71.4
5
35.7
5
35.7
3 No.
Survival %
9
100
9
100
9
100
9
100
9
100
7 No.
Survival %
10
100
10
100
10
100
10
100
9
90
6 No.
Survival %
8
100
8
100
5
62.5
2
25.0
1
12.5
Total No. :
Total Rate:
Survivals
of Survivals
47
100
45
95.7
38
80.9
29
61.7
26
55.3

Editors Note: Reproduced by kind permission of Chris Newman. Originally published in the Reptilian magazine
This site has information on the following genera of Ratsnakes ... Spilotes, Spalerosophis, Ptyas, Zamenis, Elaphe, Rhinechis, Senticolis, Pseudelaphe, Pantherophis, Bogertophis, Orthriophis, Gonyosoma, Oreocryptophis, Oocatochus, Euprepiophis, Coelognathus, Archelaphe