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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.

°C

No. Eggs

Days

Notes

           
Coelognathus          
  erythrurus   6-10 90-120 Multiple clutches may be produced in one year
  helena helena 26-29°C 3-12 50-96 2-6 clutches produced per year
  helena monticollaris   8    
  radiatus 27-29°C 6-23 64-95 2-6 clutches produced per year although 9 has been recorded for this species ( Ryabov 1997)
  flavolineatus 27-29°C 5-12 75-109 2-4 clutches produced per year
  subradiatus 27-29°C 5-10 70-78 Multiple clutches per year
Elaphe          
  anomala 25-29°C 6-12 35-60  
  bimaculata 25-28°C 3-10 35-48 Produces only one clutch per year
  carinata 25-28°C 6-15 41-58  
  climacophora 25-29°C 7-24 44-75 May double clutch in spring and autumn.
  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 Can be difficult to incubate, manual pipping is often required at round day 90 then left to hatch by themselves.
  oxycephalum 26-30°C 5-12 87-125 Can be difficult to incubate, manual pipping is often required at round day 90 then left to hatch by themselves. May lay up to 4 clutches per year
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 Thick leathery shells
  taeniurus friesi 25-32°C 8-25 55-77 Thick leathery shells can double clutch
  taeniurus grabowskyi       Thick leathery shells
  taeniurus mocquardi   5-15    
  taeniurus ridleyi 27-28°C 7-15 65-70 Eggs are softer than any of the other ssp. (Schulz 1996)
  taeniurus schmackeri       Thick leathery shells
  taeniurus ssp.       Thick leathery shells
  taeniurus yunnanensis 27-28°C 5-15 68-71 Thick leathery shells
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  
           
Rhadinophis          
  frenatum    9  55  
  prasinum 25-29°C 3-11 68-85 Lower incubation temps are recommended for this species as some breeders are reporting D.I.E when incubated at 28-29C. May double clutch. Mating starts in brumation when temperatures rise above 18C (Ryabov)
 
 
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 May double clutch in spring and autumn
  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 May double clutch
  obsoletus lindheimeri 26-29°C 60-73 3-30 May double clutch
  obsoletus obsoletus 25-29°C 50-109 5-44 May double clutch
  obsoletus quadrivittata 25-29°C 49-73 3-22 May double clutch
  obsoletus spiloides 25-29°C 60-96 6-21 May double clutch
  guttaus 25-29°C 51-102 3-32 2 clutches per year is not uncommon
  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 May double clutch
Senticolis          
  triaspis intermedia 25-29°C 75-100 3-9 Only one clutch per year
  triaspis mutabilis 25-29°C 75-100 3-9 Sperm storage has been reported for this species (Schulz 1992)
  triaspis triaspis       can double clutch
 
 
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  
           
           

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)


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