Growing data of four juvenile melanistic Common Garter Snakes
Thamnophis sirtalis sirtalis
Copyright 1998 Martin Hallmen

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Introduction

The melanistic Common Garter Snake Thamnophis sirtalis sirtalis (Figure 1) is not very common in European terraria. Only a very few specimens of this black color phase were introduced to Europe so far. No wonder that recently effects of inbreeding are discussed (BOL, 1996; SCHMIDT, 1997; CHLEBOWY, 1997). This rareness is one of the reasons that there nearly no data exist about a healthy keeping and breeding of this attractive snake. But as a possible result of inbreeding effects problems in keeping melanistic Common Garter Snakes occur regularly. Especially juvenile and semiadult snakes die without any visible reason. Data about the normal growing of young melanistic Thamnophis sirtalis sirtalis might help to recognize problems in the development right in time.
Material and methods

The observations were made on 2,2 melanistic garter snakes of the species Thamnophis sirtalis sirtalis. At the beginning of the observations all of them were 3 months old. Information about the descent of the animals and the keeping conditions are published in HALLMEN (1997a). The animals were fed with total smelts (Osmerus eperlanus) (HALLMEN, 1998) every 2-3 days. The time of day mostly was in the evening. In nearly every feeding time more smelts were offered than could be eaten by the snakes. Sometimes the smelts were dusted with a vitamin powder. The observation were made over a period of 20 weeks (HALLMEN, 1997b). The body weight was measured by putting the snake into a plastic bag, closing the bag with an elastic and hanging it at a spring balance (Figure 2). The body length was found out by stretching the snake out on a tape measure. All measurements were repeated every 2 weeks.
Results

Table 1 shows the results for the body weight of the 4 specimens of melanistic Common Garter Snakes. The 2 males were first measured with 9 g / 10 g grow up to 33 g / 37 g. The increase of body weight was much more in the 2 female snakes. It ranges from 13 g / 15 g to 95 g / 100 g in the period of 20 weeks. The length of the body (Table 2) also increases more in the females. The males range from 31 cm / 32 cm to 49 cm / 54 cm. The 2 females could be measured with 31 cm / 35 cm at the beginning and 67 cm / 68 cm at the end of the 20 weeks' period. The times between the sheddings of the old skin varied fom 10 days minimum to 25 days maximum. There could be seen no regularity. There also was no difference between the male and female snakes.
Discussion

The results show a normal growth of the 4 juvenile melanistic Common Garter Snakes. Usually female Garter Snakes - .like most other snakes do - grow faster and become bigger than male snakes. This could be shown for the melanistic phase of Thamnis sirtalis sirtalis too. According to CHLEBOWY (pers. information) the problems in keeping and breeding melanistic garter snakes result in no suitable keeping conditions. I think most hobbiists keep these magnificent snakes too cold. Melanistic garters should have a minimum of 2 heat sources. This should be realized especially for juvenile and semiadult snakes in an indoor terrarium. Things may look different in an outdoor terrarium (BOL, 1997 a+b). The sun is much stronger than heat sources in a tank and will heat up a black snake pretty fast. For more information read HALLMEN & CHLEBOWY (1998).
Acknowledgements

I thank my colleague Karin BERGMANN for her help with the translation of this article. And thanks to Rob JANSEN for the translation of the abstract into Dutch.
Literature

BOL, S. (1997a): The melanistic common garter snake in the outdoor terrarium. - The Garter Snake, 2/97: 2-8. BOL, S. (1997b): The melanistic common garter snake (Thamnophis sirtalis sirtalis) in the outdoor terrarium (Part 2). - The Garter Snake, 3/97: 8-22. HALLMEN, M. (1997a): Some observations on stages of shedding in juvenile melanistic Common Garter Snakes Thamnophis sirtalis sirtalis. - The Garter Snake, 4/97: 19-23. HALLMEN, M. (1997b): A blank form for recording distinctive marks in the melanistic Common Garter Snake Thamnophis sirtlalis sirtalis. - The Garter Snake, 4/97: 13-19. HALLMEN, M. (1998): The smelt Osmerus erperlanus as a prey fish for Garter Snakes of the genus Thamnophis in the terrarium. - The Garter Snake: in print. HALLMEN, M. & CHLEBOWY, J. (1998): Die Haltung von melanistischen Strumpfbandnattern Thamnophis sirtalis sirtalis. - Elaphe, 3/98: In pint.
Zusammenfassung

Es werden Daten zum Gewicht, zur Körperlänge und zu den Häutungsabständen von 4 juvenilen melanistischen Strumpfbandnattern Thamnophis sirtalis sirtalis gegeben. Die Ergebnisse zeigen ein für Strumpfbandnattern normales Wachstum. Dies wird unter anderem auf die vergleichsweise warme Haltung der Tiere zurück geführt.