Introduction

This is a guide to the incubation temperatures, incubation duration and clutch size of most Ratsnake species and subspecies with notes on eggs and incubation.

A few notes on eggs and incubation.

The incubation of Ratsnake eggs is pretty straight forward, with no special incubation requirements needed. They can be incubated in a variety of moist substrates including some of the more popular, medium grade vermiculite, sphagnum moss, perlite and peat moss / sand mixtures. The incubation medium only needs to be moist not wet, as a general rule of thumb, when squeezed in the palm of your hand there should be no or very little water escape.

For most Ratsnakes the incubation temperature falls between 26-29C with temperatures over 30C and under 25C either being fatal to the eggs or the developing embryo's will show some signs of deformity. For a lot of Ratsnakes the most commonly preferred temperature of incubation by breeders is 27C this results in a slightly longer incubation but the resulting hatchlings are stronger.

Relative air humidity which I haven't recorded in the table as a general rule should be within 80-100%. This is easily achieved because a damp substrate in a sealed container will quickly saturate the air giving a 100% relative air humidity.

Snake eggs when they are laid are covered with a mucous layer which as it dries adheres the eggs together, this happens in the first hour after being laid. If possible it is always best to separate the eggs where possible, but this can only be done within the first hour of laying, otherwise you risk traumatizing the egg. Separating the eggs has the advantage that infertile eggs and those that spoil during incubation can be removed easily. Saying this, mouldy eggs very rarely affect good ones in incubation. Good eggs have a good defence mechanism against infections, in addition to the shell providing a mechanical barrier, the albumen with a pH 9.5 prevents infection by creating a hostile environment for micro-organisms and by acting as a microbicide. This may be why we see what we think are rotten eggs hatch, as the infection has really only taken hold on the shell, the embryo has been protected from infection.

Fertile eggs when they are laid are usually a pure white colour and feel firm to the touch, whereas infertile eggs are smaller, a yellowy colour and look waxy. Several anomalies can occur on the shell of fertile eggs, which do not effect there hatching. They may have transparent patches which is a lack of calcium coating, bumps or grooves and even ice crystal shaped calcium deposits.


Eggs should be incubated in the position they are found and not rotated during incubation. Since eggs absorb water throughout incubation, if you have a large clutch of eggs this must be reflected in the size of container you incubate them in, as they may quickly cause the incubation medium to dry out and result in the eggs spoiling. As eggs go through incubation there need for oxygen increases, if there is too many eggs in too small a container then they may suffocate and die, or hatch prematurely (depending on the stage they are in development), as one of the cues for hatching is an elevated CO2 level and a decreased oxygen level.

In this guide the incubation temperature range and incubation days work together, the lower the temperature generally the longer the incubation and visa versa, the hotter the incubation temperature the quicker they will hatch.

This guide has been put together from several sources and offers some parameters for incubation, as does the basic notes in the introduction. Please research further, this is not a guide to follow for incubation, merely a quick reference to use along your own research.

ASIATIC INCUBATION TEMPERATURES, NUMBER OF EGGS & INCUBATION DAYS
Genus	sp. / spp.	Incubation °C	No. Eggs	Incubation Days
Coelognathus
	erythrurus		6-10	90-120
	helena helena	26-29°C	3-12	50-96
	helena monticollaris		8
	radiatus	27-29°C	6-23	64-95
	flavolineatus	27-29°C	5-12	75-109
	subradiatus	27-29°C	5-10	70-78
Elaphe
	anomala	25-29°C	6-12	35-60
	bimaculata	25-28°C	3-10	35-48
	carinata	25-28°C	6-15	41-58
	climacophora	25-29°C	7-24	44-75
	dione	21-30°C	3-16	13-36
	dione 'Altai'	21-27°C	3-10	20-32
	dione 'Striped'	21-27°C	3-10	17-23
	dione 'Cherskyi'	21-27°C	3-10	19-22
	dione 'China'	22-28°C	3-12	32-36
	dione 'Korea'	22-28°C	3-12	20-32
	dione 'Nigrita'	21-27°C	5-15	20-29
	quadrivigata	28-29°C	6-16	31-55
	schrencki	25-29°C	6-30	35-60
Euprepiophis
	mandarinus	25-29°C	2-9	40-59
	conspicillatus	25-28°C	2-8	43-56
Gonyosoma
	janseni	27-29°C	5	123-125
	oxycephalum	26-30°C	5-12	87-125
Rhadinophis
	frenatum		9	55
	prasinum	25-29°C	3-11	68-85
Orthriophis
	cantoris	24-30°C	5-10	84-102
	moellendorffi	26-27°C	6-12	75-83
	taeniurus taeniurus	26-28.5°C	5-15	69-99
	taeniurus friesi	25-32°C	8-25	55-77
	taeniurus grabowskyi
	taeniurus mocquardi	27-28°C	5-15
	taeniurus ridleyi	27-28°C	7-15	65-70
	taeniurus schmackeri
	taeniurus ssp.	27-28°C	8-20	60
	taeniurus yunnanensis	27-28°C	5-15	68-71
Oreocryptophis
	porphyraceus porphyraceus	24-27°C	3-7	49-60
	porphyraceus coxi	25-27°C	2-3	53-60
	porphyraceus laticincta	24-27°C	2-5	53-60
	porphyraceus vaillanti	24-27°C	1-4	45-58
EUROPEAN RATSNAKE INCUBATION TEMPERATURES, NUMBER OF EGGS & INCUBATION DAYS
Genus	sp. / spp.	Incubation °C	Incubation Days	No. Eggs
Elaphe
	quatuorlineata quatuorlineata	26-29°C	21-68	3-17
	quatuorlineata muenteri	26.5°C	54-56	8
	sauromates	27-29°C	44-64	6-16
Rhinechis
	scalaris	25-29°C	51-71	5-24
Zamenis
	hohenackeri hohenackeri	26-28°C	42-70	2-7
	longissimus	25-29°C	42-65	5-18
	persicus	28-29°C	45-55	4-8
	situla	24-28°C	2-12	50-85
AMERICAN RATSNAKE INCUBATION TEMPERATURES, NUMBER OF EGGS & INCUBATION DAYS
Genus	sp. / spp.	Incubation °C	Incubation Days	No. Eggs
Bogertophis
	rosaliae	28-29°C	80-90	4-9
	subocularis	25-29°C	64-105	5-14
Pantherophis
	bairdi	25-29°C	52-83	4-15
	obsoletus lindheimeri	26-29°C	60-73	3-30
	obsoletus obsoletus	25-29°C	50-109	5-44
	obsoletus quadrivittata	25-29°C	49-73	3-22
	obsoletus spiloides	25-29°C	60-96	6-21
	guttaus	25-29°C	51-102	3-32
	emoryi	26-29°C	6-16	52-85
	vulinus vulpinus	23-29°C	31-65	7-29
	vulpinus gloydi	27°C	43-44	14
Pseudelaphe
	flavirufus flavirufus	27-29°C	50-60	4-9
	flavirufus pardalina	27-29°C	50-60	4-9
Senticolis
	triaspis intermedia	25-29°C	75-100	3-9
	triaspis mutabilis	25-29°C	75-100	3-9
	triaspis triaspis
COMMON NAME RATSNAKE INCUBATION TEMPERATURES, NUMBER OF EGGS & INCUBATION DAYS
Pseustes
	sulphureus	28	84-86	7
Ptyas
	mucosus	27-30°C	53-78	5-14
	korros	30°C	55	7-14
Rhynchophis
	boulengeri	27-29°C	55-63	5-10
Spalerophis
	cliffordi	24-30°C	59-84	3-16
Spilotes
	pullatus	25-30°C	54-76	5-25

References

1. A Monograph of the colubrid Snakes ofthe Genus Elaphe FITZINGER. Klaus-Dieter Schultz. 1996
2. The Snakes of Thailand and their Husbandry. Merel J. Cox
3. Incubation of Reptile Eggs. Gunther Kohler
4.On the extraordinary reproduction of Elaphe radiata. Sergei A. Ryabov. Russian Journal of herpetology 1997. Volume 4. No. 2
5. http://members.1012surfnet.at/sommerauer/index.htm (C.helena. monticollaris)
6. Elaphedione.com (incubation details for the various E. dione localities)
7. Rareratsnakes.com (incubation details on C.s.subradiatus)
8. Variation, distribution and biology of Elaphe triaspis (COPE 1866) with remarks on the husbandry and captive breeding of the Southern subspecies Elaphe triaspis mutabilis (COPE 1885). Klaus-Dieter Schulz. Part.2 Litteratura Serpentarium. 12 (3): 54-68
9. Common Rat Snake of India Ptyas Mucosus. Shiv Dutta 2005
10. http://www.reptilia.dk/Opdraetsresultater/breedingresults.html (incubation details for E.quatuorlineata muenteri)
11. Eine seltene Natter aus Nepal, Elaphe cantoris (Boulenger, 1894). Helfenberger N., K. B. Shah, N. L. Orlov & G.-D. Guex (2000) Sauria, Berlin, 22 (2): 3-10.
12. Peculiarities of the reproductive biology of the Japanese Ratsnake Elaphe climacophora Boie, 1826 (Colubridae). Kudryavtsev O. B.
13. Breeding of rare species of rat-snakes of the Elaphe genus of the South-East Asian fauna. Ryabov S.A.
14.Tabachishin Vasily Grigorievitch. Dione snake in Povolzhye (http://proeco.visti.net/naturalist/aquarium/elaphe.htm)
15. http://nature.tesri.gov.tw/tesriusr/internet/natshow.cfm?IDNo=726 (Gonyosoma frenatum)

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