Rat snake

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Rat snake
Zamenis longissimus.jpg
Aesculapian snake (Zamenis longissimus)
Scientific classification OOjs UI icon edit-ltr.svg
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Class: Reptilia
Order: Squamata
Suborder: Serpentes
Family: Colubridae
Subfamily: Colubrinae
Genera

See text

Rat snakes are members – along with kingsnakes, milk snakes, vine snakes and indigo snakes – of the subfamily Colubrinae of the family Colubridae. They are medium to large constrictors and are found throughout much of the Northern Hemisphere. They feed primarily on rodents. Many species make attractive and docile pets and one, the corn snake, is one of the most popular reptile pets in the world. Like all snakes, they can be defensive when approached too closely, handled, or restrained. However, rat snake bites are not dangerous to humans. Like nearly all colubrids, rat snakes pose no threat to humans. Rat snakes were long believed to be completely nonvenomous, but recent studies have shown that some Old World species do possess small amounts of venom, though the amount is negligible relative to humans. [1]

Previously, most rat snakes were assigned to the genus Elaphe , but many have been since renamed following mitochondrial DNA analysis performed in 2002. For the purpose of this article, names will be harmonized with the TIGR Database.

Species

Old World rat snakes

Gray rat snake, Pantherophis spiloides Black Rat Snake-.JPG
Gray rat snake, Pantherophis spiloides
Red-tailed green rat snake, Gonyosoma oxycephalum Elaphe oxycephala1.jpg
Red-tailed green rat snake, Gonyosoma oxycephalum
Rhinoceros ratsnake, Rhynchophis boulengeri Rhynchophis boulengeri head (edited).jpg
Rhinoceros ratsnake, Rhynchophis boulengeri
Mandarin rat snake, Euprepiophis mandarinus Elaphe mandarina.jpg
Mandarin rat snake, Euprepiophis mandarinus

Coelognathus spp.

Elaphe spp.

Euprepiophis spp.

Gonyosoma spp.

Oreocryptophis spp.

Orthriophis spp.

Ptyas spp.

Rhadinophis spp.

Rhynchophis spp.

Zamenis spp.

Black ratsnake, Pantherophis obsoletus (formerly Elaphe obsoleta obsoleta): The blue eyes indicate the snake is in a shed cycle. Black Rat Snake.jpg
Black ratsnake, Pantherophis obsoletus (formerly Elaphe obsoleta obsoleta): The blue eyes indicate the snake is in a shed cycle.
Yellow rat snake Pantherophis sp. (formerly Elaphe obsoleta quadrivittata) from Florida Elaphe obsoleta quadrivittata.jpg
Yellow rat snake Pantherophis sp. (formerly Elaphe obsoleta quadrivittata) from Florida

New World rat snakes

Bogertophis spp.

Pantherophis spp.

Pseudelaphe spp.

Senticolis spp.

Spilotes spp.

Nota bene : In the above species lists, an authority's name in parentheses indicates that the species was originally described in a different genus. An authority's name not in parentheses indicates that the species is still assigned to the original genus in which it was described.

Taxonomy

In recent years, some taxonomic controversy has occurred over the genus of North American rat snakes. Based on mitochondrial DNA, Utiger et al. (2002) showed that North American rat snakes of the genus Elaphe, along with closely related genera such as Pituophis and Lampropeltis, form a monophyletic group separate from Old World members of the genus. They therefore suggested the resurrection of the available name Pantherophis Fitzinger for all North American taxa (north of Mexico). [2] [3] Crother et al. (2008) accepted the taxonomic change to Pantherophis. [4]

Venom

Like nearly all colubrids, rat snakes pose no threat to humans. Although rat snakes were long believed to be completely nonvenomous, recent studies have shown that some Old World species do possess small amounts of venom, though the amount is negligible relative to humans. [1] Rat snakes usually hunt and kill mice and other small animals by grasping with their teeth to prevent escape, wrapping their body around that of the prey, and suffocating the prey by constriction.

In captivity

Rat snakes are commonly kept as pets by reptile enthusiasts. The corn snake, one of the most popular pet reptiles, is a rat snake. New World species are generally thought to be more docile in captivity as opposed to Old World rat snakes, of which the opposite is assumed. [5]

Effects of climate change on rat snakes

Positive impacts

All snakes are ectotherm species, meaning they depend on the temperature of the environment to maintain homeostasis. [6] Although it is predicted that the current rate of climate change will be too rapid for many reptiles and amphibian species to adapt or to evolve, [7] studies have suggested that a warmer climate may actually be beneficial to rat snake species. Global warming also poses less threats to rat snakes in temperate zones than in tropical zones as rat snake species in temperate zones can tolerate broader ranges of temperature. [8] Global climate change will increase both day and night time temperatures. This will make the night time environment more thermally suitable for rat snakes to hunt, thereby making them more active at night. [9] Increasing night time activity allows rat snakes to catch larger prey such as birds, since female birds usually incubate their eggs in the nest at night and have decreased ability to detect rat snakes due to poor visibility conditions. Global warming may also lead to changes in predation. Rat snakes are prey species to predators like hawks. While rat snakes are being hunted during the day, being more active at night due to warmer temperatures may allow rat snakes to be less vulnerable to predation from hawks. [9] A warming climate also enhances food digestion in rat snakes thereby making them more efficient, which enables rat snake individuals to grow larger in size and allowing them to consume more prey. [10] In comparison to rat snake species at relatively colder regions, rat snake species at lower latitudes tend to be larger in size due to warmer climate conditions. As the global climate warms, the average body size of rat snakes at higher latitudes will become larger, which will allow the species to catch more prey and thus increase their overall reproductive success. [11]

Negative impacts

Eastern rat snake species in North America are experiencing negative shifts in their behaviour due to Global Warming and increasing temperatures. These shifts differ between the large distribution of rat snakes that range from Ontario to Texas. [8] The increasing Global Warming can negatively impact this species and can be responsible for population declines in some areas.

Rat snake populations from their northern range, such as Ontario, are experiencing a shift in hibernation emergence. [12] The populations in these regions typically emerge from hibernation in late April. [12] However, the increasing variability in temperature may cause rat snakes to emerge on a warm sunny day in the months of February or March. [8] Climate change has caused winters that can have weather turn back very quickly from sunny periods with high temperatures to snow and below freezing temperatures. The early emergence of these rat snakes will begin to expose them to these fatal conditions if a snake cannot return to its hibernaculum in time. [8] Therefore, the fluctuations in temperature affect the thermoregulation that rat snakes need for bodily functions like digestion and movement. [10] The unpredictability of the weather is causing more rat snakes in their northern range to get caught in these cold snaps and freeze to death. [12]

Increasing temperatures due to climate change have increased the nocturnal activity of rat snakes, especially in warmer climates such as Texas. [8] This has allowed them to alter their predation habits and feed more on nesting birds and other accessible prey. [13] However, their increased nocturnal activity puts them at risk to a new range of nocturnal predators. Rat snakes may not be used to the presence of nocturnal predators such as raccoons and owls and may be more vulnerable as prey. [14] Until rat snakes are able to adapt to their relatively new predators, populations may be at risk due to heavy predation.

Life history alterations in Ontario gray rat snakes

As rat snakes are ectothermic species, they require sunlight and heat to maintain their body temperatures. Across their range in North America each species of rat snake has different ideal body temperatures. In Ontario, the average ideal body temperature of a rat snake is 28.1 degrees Celsius with free ranging gravid females tending to require a bit higher in order to meet their thermoregulatory requirements for gestation. [15] With ambient air temperatures over the course of their entire active season (from May to September) almost never reaching the required 28.1 °C, rat snakes in Ontario resort to basking habitats where conditions allow temperatures to rise above normal and up to 43 degrees Celsius at the hottest times of day and year. [15] These habitats include areas such as rock outcrops, bare ground, or edge habitat where they can bask on tree branches fully exposed to the sun. However, with climate change and an associated increase in ambient air temperature by 3 °C, the amount of required time spent by snakes in these habitats will decrease. [16] This will result in alterations in the amount and time of activity of rat snakes in the province. They will have the potential to be generally more active during both the day and night as it will be easier for them to maintain their ideal body temperature. Habitat choices may also shift with increased temperatures. More time could be spent in areas such as forests or barns where the temperatures are currently too low for the snakes to spend most of their time. [15] There will be less of a need to expose themselves in their open basking habitats, causing decreases in predator vulnerability as well as increases in thermoregulatory ability and foraging time. In addition, rat snakes in Ontario have a slower growth and maturation rates due to the cooler climate and shorter active seasons compared to other species of rat snakes further South in North America. [17] This means that Ontario's rat snakes are more vulnerable to population declines. But, with an increase in temperature and an increase in the duration of the active season from climate change, it is possible that the growth and maturation rates of these snakes will increase. [18]

See also

Related Research Articles

<span class="mw-page-title-main">Corn snake</span> Species of snake

The corn snake, sometimes called red rat snake, is a species of North American rat snake in the family Colubridae. The species subdues its small prey by constriction. It is found throughout the southeastern and central United States. Though superficially resembling the venomous copperhead and often killed as a result of this mistaken identity, the corn snake lacks functional venom and is harmless. The corn snake is beneficial to humans because it helps to control populations of wild rodent pests that damage crops and spread disease.

<i>Pantherophis obsoletus</i> Species of snake

Pantherophis obsoletus, also known commonly as the western rat snake, black rat snake, pilot black snake, or simply black snake, is a nonvenomous species of snake in the family Colubridae. The species is native to central North America. There are no subspecies that are recognized as being valid. Its color variations include the Texas rat snake. Along with other snakes of the eastern United States, like the eastern indigo snake and the eastern racer, it is called “black snake”.

<span class="mw-page-title-main">Beauty rat snake</span> Species of snake

The beauty rat snake, also called the beauty ratsnake, the beauty snake, or the cave racer, is a species of snake in the family Colubridae. The species is native to the eastern and southeastern regions of Asia. It is a long, thin, semi-arboreal species of snake with several recognized subspecies. This constrictor feeds on rodents, and though it is favored in some locations as a natural pest control or pet, it is also considered an invasive species in other locations.

<span class="mw-page-title-main">Jamaican boa</span> Species of snake

The Jamaican boa, Jamaican yellow boa or yellow snake is a boa species endemic to Jamaica. No subspecies are recognized. Like all other boas, it is not venomous.

<i>Elaphe</i> Genus of rat snakes

Elaphe is a genus of snakes in the family Colubridae. Elaphe is one of the main genera of the rat snakes, which are found in many regions of the northern hemisphere. Elaphe species are medium to large constrictors by nature.

<span class="mw-page-title-main">Mandarin rat snake</span> Species of snake

The mandarin rat snake is a species of nonvenomous colubrid snake endemic to Asia. It is closely related to Euprepiophis conspicillata, the Japanese forest rat snake. Mandarin rat snakes are one of the most popular rat snakes found in the pet trade.

<i>Oreocryptophis</i> Genus of snakes

Oreocryptophis porphyraceus is a rat snake species, commonly called the black-banded trinket snake, red bamboo snake, found in mid to upper-level elevations of forested hills in southeastern Asia, ranging from evergreen tropical to dry seasonal forests depending on the subspecies and locality. It is the only member of the genus Oreocryptophis, but it was formerly placed in Elaphe.

<span class="mw-page-title-main">Radiated ratsnake</span> Species of snake

Coelognathus radiatus, commonly known as the radiated ratsnake, copperhead rat snake, or copper-headed trinket snake, is a nonvenomous species of colubrid snake.

<span class="mw-page-title-main">Trans-Pecos rat snake</span> Species of snake

The Trans-Pecos rat snake or Davis Mountain rat snake, is a species of medium to large, nonvenomous rat snake in the family Colubridae. Bogertophis subocularis is endemic to the Chihuahuan Desert.

<span class="mw-page-title-main">Texas rat snake</span> Subspecies of snake

The Texas rat snake is a subspecies of the black rat snake, a nonvenomous colubrid. It is found in the United States, primarily within the state of Texas, but its range extends into Louisiana, Arkansas and Oklahoma. It intergrades with other subspecies of Elaphe obsoleta, so exact range boundaries are impossible to distinguish. The epithet lindheimeri is to honor the German-American naturalist Ferdinand Jacob Lindheimer, who collected the first specimen in New Braunfels, Texas.

<i>Pantherophis emoryi</i> Species of snake

Pantherophis emoryi, commonly known as the Great Plains rat snake, is a species of nonvenomous rat snake in the family Colubridae. The species is native to the central part of the United States, from Missouri to Nebraska, to Colorado, south to Texas, and into northern Mexico.

<i>Pantherophis bairdi</i> Species of snake

Pantherophis bairdi is a species of harmless snake in the family Colubridae. The species is native to the southwestern United States and adjacent northeastern Mexico. No subspecies are recognized as being valid.

<i>Elaphe schrenckii</i> Species of snake

Elaphe schrenckii is a species of nonvenomous snake in the family Colubridae. The species is indigenous to Northeast Asia.

<i>Elaphe carinata</i> Species of snake

Elaphe carinata, the king ratsnake, is a species of Colubrid snake found in Southeast and East Asia.

<i>Euprepiophis conspicillata</i> Species of snake

Euprepiophis conspicillata, commonly known as the Japanese forest rat snake, is a species of nonvenomous colubrid snake endemic to Japan. Its Japanese common name, jimuguri, roughly translates to "the burrower". It is closely related to Euprepiophis mandarinus, the Mandarin rat snake.

<span class="mw-page-title-main">Japanese striped snake</span> Species of snake

Elaphe quadrivirgata, commonly known as the Japanese four-lined ratsnake or the Japanese striped snake, is a species of non-venomous colubrid snake native to Japan.

<i>Euprepiophis</i> Genus of snakes

Euprepiophis is a genus of nonvenomous colubrid snakes, containing three species of Asian rat snakes which were formerly assigned to the genus Elaphe. They were separated from Elaphe in 2002 by Utiger et al. following evidence from DNA analysis. They are true rat snakes but are not as closely related to other European, Asian, or North American rat snakes as their former place in Elaphe might suggest.

<i>Coelognathus</i> Genus of snakes

Coelognathus is a genus of seven species of rat snakes in the subfamily Colubrinae of the family Colubridae. The species, which are native to South Asia and Southeast Asia, were formerly assigned to the genus Elaphe. Based on morphological evidence and protein similarities, in 2001, Helfenberger revalidated the name Coelognathus that had originally been proposed by Leopold Fitzinger in 1843. The distinction between Coelognathus and Elaphe was further supported by mitochondrial DNA sequence and additional morphological evidence in 2005.

<i>Pantherophis alleghaniensis</i> Species of snake

Pantherophis alleghaniensis, commonly called the eastern rat snake, is a species of nonvenomous snake in the family Colubridae. The species is endemic to North America.

<i>Elaphe anomala</i> Species of snake

Elaphe anomala commonly known as the Korean rat snake, GuReongEe is a non-venomous species of colubrid snake known from China and Korea. Its common names include Amur ratsnake, southern Amur ratsnake. It is a semi-arboreal snake that can be found in grasslands, dry scrub, rocky areas, and on the banks of rivers and lakes. It grows to 150–180 cm (59–71 in).

References

  1. 1 2 Fry, Bryan G.; Lumsden, Natalie G.; Wüster, Wolfgang; Wickramaratna, Janith C.; Hodgson, Wayne C.; Kini, R. Manjunatha (1 October 2003). "Isolation of a neurotoxin (alpha-colubritoxin) from a nonvenomous colubrid: evidence for early origin of venom in snakes". Journal of Molecular Evolution. 57 (4): 446–452. doi:10.1007/s00239-003-2497-3. ISSN   0022-2844. PMID   14708577. S2CID   21055188.
  2. ↑ Utiger U, Helfenberger N, Schätti B, Schmidt C, Ruf M, Ziswiler V (2002). "Molecular systematics and phylogeny of Old and New World ratsnakes, Elaphe auct., and related genera (Reptilia, Squamata, Colubridae)" (PDF). Russian Journal of Herpetology. 9 (2): 105–124. Archived from the original (PDF) on 24 September 2015. Retrieved 14 October 2016.
  3. ↑ Elaphe obsoleta Archived 14 April 2009 at the Wayback Machine at The Center for North American Herpetology. Accessed 20 June 2008.
  4. ↑ Crother BI, et al. (2008) Scientific and Standard English Names of Amphibians and Reptiles of North America North of Mexico: 6th edition. Herp. Rev. 37, pp. 58–59. or see pp. 64 ff in the 7th edition.
  5. ↑ Bartlett, Richard D.; Bartlett, Patricia Pope (2006). Corn Snakes and Other Rat Snakes: Everything about Acquiring, Housing, Health, and Breeding. Barron's Educational Series. p. 8. ISBN   978-0-7641-3407-4.
  6. ↑ Vieira Andrade, Denis; Gavira, Rodrigo S.B.; Tattersall, Glenn J. (30 December 2015). "Thermogenesis in ectothermic vertebrates". Temperature (Austin). 2 (4): 454. doi:10.1080/23328940.2015.1115570. PMC   4843938 . PMID   27227064.
  7. ↑ Bickford, David; Howard, Sam D.; Ng, Daniel J.J.; Sheridan, Jennifer A. (April 2010). "Effects of Climate Change on the amphibians and reptiles of Southeast Asia". Biodiversity and Conservation. 19 (4): 1043–1062. doi:10.1007/s10531-010-9782-4. S2CID   4462980.
  8. 1 2 3 4 5 Weatherhead, Patrick J.; Sperry, Jinelle H.; Cargagno, Gerardo L.F.; Blouin-Demers, Gabriel (July 2012). "Latitudinal variation in thermal ecology of North American ratsnakes and its implications for the effect of climate warming on snakes". Journal of Thermal Biology. 37 (4): 273–281. doi:10.1016/j.jtherbio.2011.03.008.
  9. 1 2 Larson, Debra Levey. "Global warming beneficial to ratsnakes". ACES Illinois. College of Agricultural, Consumer, and Environmental Sciences. Retrieved 24 March 2018.
  10. 1 2 Knight, Kathryn (2010). "Timeframe affects snakes' ability to cope with climate change". Journal of Experimental Biology. 213 (2): ii. doi: 10.1242/jeb.041467 .
  11. ↑ Shine, Richard (22 May 2003). "Reproductive Strategies in Snakes". Proceedings: Biological Sciences. 270 (1519): 995–1004. doi:10.1098/rspb.2002.2307. PMC   1691341 . PMID   12803888.
  12. 1 2 3 Blouin-Demers, G; Prior, Kent; Weatherhead, P.J. (1 June 2000). "Patterns of variation in spring emergence by black rat snakes (Elaphe obsoleta obsoleta)". Herpetologica. 56: 175–188.
  13. ↑ Sperry, Jinelle; P. Ward, Michael; J. Weatherhead, Patrick (1 March 2013). "Effects of Temperature, Moon Phase, and Prey on Nocturnal Activity in Ratsnakes: An Automated Telemetry Study". Journal of Herpetology. 47: 105–111. doi:10.1670/11-325. S2CID   33710484.
  14. ↑ DeGregorio, Brett A.; Westervelt, James D.; Weatherhead, Patrick J.; Sperry, Jinelle H. (24 September 2015). "Indirect effect of climate change: Shifts in ratsnake behavior alter intensity and timing of avian nest predation". Ecological Modelling. 312: 239–246. doi: 10.1016/j.ecolmodel.2015.05.031 . ISSN   0304-3800.
  15. 1 2 3 Blouin-Demers, Gabriel; Weatherhead, Patrick J. (1 November 2001). "Thermal Ecology of Black Rat Snakes (Elaphe Obsoleta) in a Thermally Challenging Environment". Ecology. 82 (11): 3025–3043. doi:10.1890/0012-9658(2001)082[3025:teobrs]2.0.co;2. ISSN   1939-9170.
  16. ↑ Weatherhead, Patrick J.; Sperry, Jinelle H.; Carfagno, Gerardo L.F.; Blouin-Demers, Gabriel (2012). "Latitudinal variation in thermal ecology of North American ratsnakes and its implications for the effect of climate warming on snakes". Journal of Thermal Biology. 37 (4): 273–281. doi:10.1016/j.jtherbio.2011.03.008.
  17. ↑ Blouin-Demers, Gabriel; Prior, Kent A.; Weatherhead, Patrick J. (1 January 2002). "Comparative demography of black rat snakes (Elaphe obsoleta) in Ontario and Maryland". Journal of Zoology. 256 (1): 1–10. doi:10.1017/s0952836902000018. ISSN   1469-7998. S2CID   85958037.
  18. ↑ "Black Rat Snake". www.psu.edu. Retrieved 9 April 2018.
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