Corn snake
| Corn snake | ||||||||||||
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Corn snake ( Pantherophis guttatus ) |
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| Pantherophis guttatus | ||||||||||||
| ( Linnaeus , 1766) |
The corn snake ( Pantherophis guttatus ), even ordinary corn snake is a non-toxic snake from the family of snakes (Colubridae) and in North America is home. With a typical body length of 120 to 150 cm, it is one of the medium-sized species within the genus of the American climbing snakes ( Pantherophis ). As a crepuscular and nocturnal ambulance hunter, it feeds on small mammals , amphibians , reptiles and birds . Due to its large distribution area, which extends over large parts of the eastern USA , the species is very variable in its appearance .
description
Corn snakes reach a body length of 120 cm to 150 cm, in exceptional cases even more than 180 cm (the record described is 189 cm). The corn snake is one of the medium-sized snakes within the genus Pantherophis . The weight of an adult corn snake can vary considerably depending on the season and nutritional status and ranges from 200 g in young, sexually mature animals to over 800 g in very large and well-nourished individuals.
It is difficult to differentiate between the sexes based on external characteristics. Information about the sex can be given in the male by the presence of hemipenic pockets, a less pointed tail section and the presence of a lower number of subcaudalia in the female in direct comparison.
The body of the corn snake is generally slim, the head is only slightly set off. The eyes are large and almost immobile, the large, round pupil is enclosed by a brown iris ring . The 4th and 5th, alternatively also the 5th and 6th of the 8–9 upper lip shields ( supralabials ) are in contact with the eye, which is surrounded by a pre- ocular , two post-ocular and a large supra-ocular. The number of 203–245 ventralia and 47–84 subcaudalia increases from north to south within the distribution area. The anal shield is divided.
The corn snake is very variable in color and drawing due to its large distribution area, the basic color ranges from a dull gray to a strong brown-orange. The 34–47 rectangular, more or less black bordered body and tail spots ("saddle spots") mostly have an orange to reddish-brown color and are in their shape and number an important feature to differentiate the corn snake from its very similar Prairie Corn Snake ( Pantherophis emoryi ). A change in the intensity of the coloration can also be observed in Pantherophis guttatus along the north-south line of the distribution area, whereby the rather poorly contrasting gray-brown colored individuals from northern populations differ significantly from their more reddish, contrasting and color-intensive conspecifics from the south distinguish. The light belly side is characterized by a "checkerboard pattern" typical of the corn snake, which consists of alternating, light and brown-black, rectangular scales. The top of the head is decorated with a variable ornament, which overflows into the first saddle spot on the neck.
Habitat and Distribution
The distribution area of the corn snake stretches along the east coast of the United States from the state of New York to the Florida Keys . The westernmost populations of Pantherophis guttatus are found in the states of Mississippi , Louisiana and Tennessee , where the range borders on the habitats of the Slowinski corn snake ( Pantherophis slowinskii ) and the prairie corn snake ( Pantherophis emoryi ).
Due to its large distribution area, the corn snake inhabits a wide variety of habitats, some of which differ considerably in their geographic composition and local climate. Their habitat ranges from habitats at sea level up to higher altitudes of over 750 m. In the different zones of its distribution area, the corn snake inhabits deciduous and coniferous forests that are wet in summer , bush and grassland areas as well as wetlands , as a cultural successor it is also often found in the vicinity of human settlements.
Way of life
behavior
Corn snakes are generally considered to be nocturnal and crepuscular animals, but can sometimes also be observed during the day in exposed places while sunbathing. The search for suitable prey usually takes place at night or at dusk. The corn snake spends most of its life hidden under leaf litter, bark mulch, rocks and in hollow tree trunks and caves. Corn snakes are very good climbers and can therefore also be found in trees where they prey on birds or plunder their nests - water is largely avoided, although the animals are good swimmers.
Corn snakes react to threats mostly by fleeing, the typical defense behavior can only rarely be observed - the snake erects its front third in an S-posture , which is typical for many snake species , and rushes forward from it at lightning speed when the threat persists in order to take defense bites. Particularly in young corn snakes, a clear vibration with the tip of the tail can be observed in stressful situations, which creates an intimidating, rattling noise.
In large parts of the distribution area, corn snakes go into a more or less extended winter dormancy in the cooler season . For this purpose, hundreds of specimens often gather in suitable places to winter together. Depending on the local climate, this rest period lasts up to 4 months during which the animals do not eat any food.
Diet
As a crepuscular and nocturnal ambulance hunter, the corn snake feeds on a wide range of food, which mainly consists of small mammals (mice, rats), reptiles (e.g. anoles ) and amphibians; birds are also preyed on from time to time. In addition, it is known that the very climbing corn snakes also plunder bird nests and eat the eggs and young birds they contain.
The corn snake has no poison whatsoever for catching prey and therefore kills its prey by strangling. For this purpose, it wraps its very muscular body several times around the prey, which is fixed with its jaws, thereby increasing the pressure on the internal organs of its victim until death occurs. The actual swallowing act is usually preceded by a short break before the hunted prey - mostly head first - is swallowed as a whole by movements of the extremely flexible halves of the jaw and supported by twisting muscle movements of the front third of the body.
Sensory performances
The corn snake perceives its environment mainly through the vomeronasal organ on the roof of its palate , which is used to analyze the odor particles of the ambient air picked up with the forked tongue and to pinpoint their origins. By splitting the tongue, the snake is able to orient itself spatially on the basis of the information perceived olfactory . The sight of the corn snake makes her a sharp binocular vision in the long distance (up to 5 times their own body length).
Reproduction, Development and Sexual Maturity
The mating season of the corn snake begins with the completion of the first moult after hibernation (in some male specimens even earlier) in spring. Males show increased activity at this time and tirelessly roam the area in search of females ready to mate. If two males meet, bloodless ritual fights often ensue, in which the animals entwine each other and try to put the competitor down. Females signal their willingness to mate by releasing more pheromones .
Mating is usually preceded by an extensive courtship ritual in which the male pursues the female ready to mate and tries to get on her back. The mating itself takes place by introducing one of the two spiked hemipenes into the cloaca of the female and usually takes 10-30 minutes.
After a very variable gestation period of 30 to 70 days, the female usually lays her 8 to 20 soft-shelled eggs in a suitable place (e.g. under tree stumps or rocks) between April and June and then leaves the clutch. A brood care behavior in corn snakes is not known.
The young snakes, 20-30 cm long and weighing less than 10 g, hatch from the eggs after about 60 to 80 days, depending on the incubation temperature, by opening the leathery calcareous shell with their egg teeth . Up to their first molt, about 1 to 2 weeks after hatching, the neonates feed on the remains of the yolk sac that was retracted into the abdominal cavity before hatching, after which they prey on their first food independently, mostly in the form of small amphibians and reptiles, more rarely also young ones Mammals or invertebrates . Corn snakes grow quite quickly in the first three years of their life and are between 100 and 120 cm long when they reach sexual maturity at around 3 years of age (under optimal nutritional conditions, sexual maturity can occur considerably earlier, sometimes at an age of 9 months) . During the growth phase, the color and markings of the individual are subject to a clear change from the largely gray-brown youthful dress to the often intense red and orange bright color of the adult corn snake.
Corn snakes reach an age of over 20 years in captivity; little is known about life expectancy in the wild, but this is likely to be well below the maximum age reached in human hands.
Systematics and origin of name
Description history
The corn snake was first described by Carl von Linné in 1766 under the taxon Coluber guttatus , at that time it was one of the first scientifically described species of snake in North America.
Almost a century later, this classification was revised by Leopold Fitzinger and the corn snake was therefore continued in 1843 under the name Pantherophis guttatus , which is valid again today , before it - after numerous new descriptions - by G. Stebbins in 1985 under the taxon Elaphe guttata into the comprehensive genus of climbing snakes ( Elaphe , Fitzinger 1833), in which both old and new world colubrids were described.
Modern system
In detailed scientific studies of the monophyly of the genus Elaphe , Utiger et al. (2002) and Utiger et al. (2005) found clear deviations within the genus based on DNA analyzes and studies on the structure of the hemipenes, whereupon this was revised and split into 13 genera. Since then, the corn snake, along with nine closely related species, has been assigned to the reintroduced genus Pantherophis Fitzinger , 1843.
In a revision by Frank T. Burbrink (2002) published almost at the same time, the four previously described corn snake subspecies ( Elaphe guttata gutatta , E. g. Rosacea , E. g. Meahllmorum and E. g. Emoryi ) also lost their validity and became incorporated into different species, so that no subspecies of Pantherophis guttatus are recognized (status 2014).
etymology
The scientific name of the genus Pantherophis is made up of the Greek words panthera ('leopard') and ophis ('snake'). The species name guttatus, on the other hand, is Latin and translated means 'speckled'. The origin of their most commonly used English trivial name Corn Snake ('corn snake' or 'grain snake') leaves room for two explanations: One variant is the habitat of the corn snake, which prefers to ambush the rodents that are often found there in grain fields and in granaries. A further explanation of colorful Indian provides corn (engl. Indian Corn ), whose piston has similarity to the belly of the drawing Kornnatter.
The corn snake and man
As a cultural follower, the corn snake likes to stay in the vicinity of human settlements in order to ambush their prey in corn fields and in granaries. This closeness to humans in connection with their very calm temperament and the easy to maintain conditions made the corn snake a popular terrarium keeper very early on . From the numerous color mutants and local forms that occur again and again in nature, man has bred a multitude of different color varieties over the course of a few decades (even "scaleless" animals), which enjoy unbroken popularity with pet owners from all over the world.
Endangerment and protection status
The corn snake is listed as “ Least Concern ” by the IUCN , as both its habitat and the stability of the individual populations are secured and well documented for the time being.
literature
- G. Köhler, P. Berg: Corn snakes . Herpeton, Offenbach 2005, ISBN 3-936180-14-8 .
- K. Kunz: The corn snake . Natur und Tier-Verlag, Münster 2004, ISBN 3-937285-08-3 .
- D. Schmidt: Corn snakes and earth snakes . Natur und Tier-Verlag, Münster 2000, ISBN 3-931587-48-7 .
- M. Hoffmann: Manual snake care . BEDE-Verlag, 2006. ISBN 3898601358 .
- M. Glaß and D. Bohle: Basics of keeping the corn snake . Vivaria-Verlag, Meckenheim 2012, ISBN 978-3981317657 .
- M. Glaß and D. Bohle: Color and drawing variants of the corn snake . Vivaria-Verlag, Meckenheim 2012, ISBN 978-3981317664 .
Individual evidence
- ↑ L. Trutnau: Snakes in the Terrarium, Vol. 1 - Non-toxic snakes. Ulmer, Stuttgart, p. 624 - quoted in G. Köhler, P. Berg: Kornnattern. 2005 (see literature ), p. 13.
- ^ William M. Bird, Philip Peak, Danna L. Baxley: Natural history of an allopatric population of Red Cornsnakes, Pantherophis guttatus (Linnaeus, 1766) in central Kentucky, USA. In: The Journal of North American Herpetology. Year 2015, No. 1, pp. 6–11 ( PDF 130 kB)
- ^ JG Walls: The guide to owning a corn snake. TFH Publications, Neptune City 1996, p. 63.
- ^ JC Mitchell: Geographic variation of Elaphe guttata (Reptilia: Serpentes) in the Atlantic Coastal Plain. In: Copeia. Volume 1, 1977, pp. 33-41 - quoted in: G. Köhler, P. Berg: Kornnattern. 2005 (see literature ), p. 128.
- ↑ G. Köhler, P. Berg: Kornnattern. 2005 (see literature ), p. 11.
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↑ L. Trutnau: Experiences with the corn snake Elaphe guttata (Linnaeus 1766). In: Herpetofauna. Volume 7, No. 38, 1985, pp. 6-10
- cited in G. Köhler, P. Berg: Kornnattern. 2005 (see literature ), p. 128. - ^ J. Rossi: Snakes of the United States and Canada. Vol. 1 Eastern Area. Krieger, Malabar 1992, p. 209 - quoted in G. Köhler, P. Berg: Kornnattern. 2005 (see literature ), p. 128.
- ↑ G. Köhler, P. Berg: Kornnattern. 2005 (see literature ), p. 20.
- ^ WJ Hamilton, Joseph A. Pollack: The Food of Some Colubrid Snakes from Fort Benning, Georgia . In: Ecology . tape 37 , no. 3 , July 1956, ISSN 0012-9658 , p. 519-526 , doi : 10.2307 / 1930174 .
- ↑ Urs Utiger, Notker Helfenberger, Beat Schätti, Catherine Joanne Schmidt, Markus Ruf, Vincent Ziswiler: Molecular systematics and phylogeny of old and new world ratsnakes, Elaphe auct., And related genera . In: Russian Journal of Herpetology. Volume 9, No. 2, 2002, pp. 105-124 ( PDF 230 kB).
- ↑ Urs Utiger, Beat Schätti, Notker Helfenberger: The oriental Colubrine Genus Coelognathus Fitzinger, 1843 and classification of old and new world racers and ratsnakes (Reptilia, Squamata, Colubridae, Colubrinae). In: Russian Journal of Herpetology. Volume 12, No. 1, 2005, pp. 39-60 ( PDF 330 kB).
- ^ Frank T. Burbrink: Phylogeographic analysis of the cornsnake ( Elaphe guttata ) complex as inferred from maximum likelihood and Bayesian analyzes. In: Molecular Phylogenetics and Evolution. Volume 25, 2002, pp. 465-476.
