The Texas Indigo Snake (Drymarchon melanurus erebennus) is a large, nonvenomous, colubrid

Colubrid

A colubrid is a member of the snake family Colubridae. This broad classification of snakes includes about two-thirds of all snake species on earth. The earliest species of the snake family date back to the Oligocene epoch. With 304 genera and 1,938 species, Colubridae is the largest snake family...

 snake

Snake

Snakes are elongate, legless, carnivorous reptiles of the suborder Serpentes that can be distinguished from legless lizards by their lack of eyelids and external ears. Like all squamates, snakes are ectothermic, amniote vertebrates covered in overlapping scales...

 found from southern Texas

Texas

Texas is the second largest U.S. state by both area and population, and the largest state by area in the contiguous United States.The name, based on the Caddo word "Tejas" meaning "friends" or "allies", was applied by the Spanish to the Caddo themselves and to the region of their settlement in...

 south into Mexico

Mexico

The United Mexican States , commonly known as Mexico , is a federal constitutional republic in North America. It is bordered on the north by the United States; on the south and west by the Pacific Ocean; on the southeast by Guatemala, Belize, and the Caribbean Sea; and on the east by the Gulf of...

 as far as Veracruz

Veracruz

Veracruz, formally Veracruz de Ignacio de la Llave officially Estado Libre y Soberano de Veracruz de Ignacio de la Llave , is one of the 31 states that, along with the Federal District, comprise the 32 federative entities of Mexico. It is divided in 212 municipalities and its capital city is...

.

Description

Texas Indigo Snakes are predominantly black in color, with a high sheen which gives their scales

Reptile scales

Reptile skin is covered with scutes or scales which, along with other characteristics, distinguish reptiles from animals of other classes . Scales are made of keratin and are formed from the epidermis...

 an amazing iridescence

Iridescence

Iridescence is generally known as the property of certain surfaces which appear to change color as the angle of view or the angle of illumination changes...

. Their underside is often a salmon pink color. They are large snakes, regularly attaining lengths beyond 6 ft (1.8 m); 8 ft (2.4 m) long specimens are not unheard of.

Habitat

Texas Indigo Snakes prefer lightly vegetated areas not far from permanent water sources, but are also found in mesquite

Mesquite

Mesquite is a leguminous plant of the Prosopis genus found in northern Mexico through the Sonoran Desert and Chihuahuan Deserts, and up into the Southwestern United States as far north as southern Kansas, west to the Colorado Desert in California,and east to the eastern fifth of Texas, where...

 savanna

Savanna

A savanna, or savannah, is a grassland ecosystem characterized by the trees being sufficiently small or widely spaced so that the canopy does not close. The open canopy allows sufficient light to reach the ground to support an unbroken herbaceous layer consisting primarily of C4 grasses.Some...

h, open grassland

Grassland

Grasslands are areas where the vegetation is dominated by grasses and other herbaceous plants . However, sedge and rush families can also be found. Grasslands occur naturally on all continents except Antarctica...

 areas, and coastal sand dune

Dune

In physical geography, a dune is a hill of sand built by wind. Dunes occur in different forms and sizes, formed by interaction with the wind. Most kinds of dunes are longer on the windward side where the sand is pushed up the dune and have a shorter "slip face" in the lee of the wind...

s. They den in burrows left by other animals.

Behavior and diet

Indigo snakes are diurnal

Diurnal animal

Diurnality is a plant or animal behavior characterized by activity during the day and sleeping at night.-In animals:Animals that are not diurnal might be nocturnal or crepuscular . Many animal species are diurnal, including many mammals, insects, reptiles and birds...

 snakes, and spend most of their time actively foraging for prey. They will consume almost anything they can overpower and swallow, including mammal

Mammal

Mammals are members of a class of air-breathing vertebrate animals characterised by the possession of endothermy, hair, three middle ear bones, and mammary glands functional in mothers with young...

s, bird

Bird

Birds are feathered, winged, bipedal, endothermic , egg-laying, vertebrate animals. Around 10,000 living species and 188 families makes them the most speciose class of tetrapod vertebrates. They inhabit ecosystems across the globe, from the Arctic to the Antarctic. Extant birds range in size from...

s, lizard

Lizard

Lizards are a widespread group of squamate reptiles, with nearly 3800 species, ranging across all continents except Antarctica as well as most oceanic island chains...

s, frog

Frog

Frogs are amphibians in the order Anura , formerly referred to as Salientia . Most frogs are characterized by a short body, webbed digits , protruding eyes and the absence of a tail...

s, turtle

Turtle

Turtles are reptiles of the order Testudines , characterised by a special bony or cartilaginous shell developed from their ribs that acts as a shield...

s, eggs

Egg (biology)

An egg is an organic vessel in which an embryo first begins to develop. In most birds, reptiles, insects, molluscs, fish, and monotremes, an egg is the zygote, resulting from fertilization of the ovum, which is expelled from the body and permitted to develop outside the body until the developing...

, and even other snakes

Ophiophagy

Ophiophagy is a specialized form of feeding or alimentary behavior of animals which hunt and eat snakes. There are ophiophagous mammals , birds , lizards , and even other snakes, such as the Central and South American mussuranas and...

, including rattlesnake

Rattlesnake

Rattlesnakes are a group of venomous snakes of the genera Crotalus and Sistrurus of the subfamily Crotalinae . There are 32 known species of rattlesnake, with between 65-70 subspecies, all native to the Americas, ranging from southern Alberta and southern British Columbia in Canada to Central...

s. Because of its aggressive attacks on rattlesnakes, many farmers in southern Texas consider it a useful ally. Hence the adage, "If it's an Indigo, let it go." They are not a typically aggressive snake, but may bite or release a foul smelling musk from its cloaca

Cloaca

In zoological anatomy, a cloaca is the posterior opening that serves as the only such opening for the intestinal, reproductive, and urinary tracts of certain animal species...

 if handled or harassed. Like many colubrid snakes, it will often shake its tail as a warning - even though it does not possess a rattle.

Reproduction

Breeding takes place, generally yearly, in the winter. Clutches that average 10-12 eggs are laid in the spring, and hatch around 80 days later. Hatchlings can be up to 26 in (66 cm) long. Maturity is reached in 2-3 years.

Conservation

The Texas Indigo Snake is listed as a threatened species

Threatened species

Threatened species are any speciesg animals, plants, fungi, etc.) which are vulnerable to endangerment in the near future.The World Conservation Union is the foremost authority on threatened species, and treats threatened species not as a single category, but as a group of three categories,...

 by the state of Texas

Texas

Texas is the second largest U.S. state by both area and population, and the largest state by area in the contiguous United States.The name, based on the Caddo word "Tejas" meaning "friends" or "allies", was applied by the Spanish to the Caddo themselves and to the region of their settlement in...

. Its primary threat is from habitat loss due to human development. Each snake requires a large home range to forage, and urban sprawl

Urban sprawl

Urban sprawl, also known as suburban sprawl, is a multifaceted concept, which includes the spreading outwards of a city and its suburbs to its outskirts to low-density and auto-dependent development on rural land, high segregation of uses Urban sprawl, also known as suburban sprawl, is a...

 is shrinking their usable habitat. Roads bisect their territory, and many snakes each year are run over by cars.

Further reading

• Herps of Texas: Drymarchon corais erebennus
• Texas Indigo Snake
• Werler, J.E. and J.R. Dixon
  James R. Dixon
  Dr. James Ray Dixon is Professor Emeritus and Curator Emeritus of Amphibians and Reptiles at the Texas Cooperative Wildlife Collection at Texas A&M University. His main research focus has been the natural history of Texas amphibians and reptiles and he has authored numerous field guides and...
  
  . 2000. Texas snakes: identification, distribution, and natural history. University of Texas Press
  University of Texas Press
  The University of Texas Press is a university press that is part of the University of Texas at Austin. Established in 1950, the Press publishes scholarly books in several areas, including Latin American studies, Texana, anthropology, U.S...
  
   Austin, Texas
  Austin, Texas
  Austin is the capital city of the U.S. state of :Texas and the seat of Travis County. Located in Central Texas on the eastern edge of the American Southwest, it is the fourth-largest city in Texas and the 14th most populous city in the United States. It was the third-fastest-growing large city in...
  
  . pp 98-102.
• Integrated Information Taxonomic System: Drymarchon melanurus erebennus.
• Crother, B.I., J. Boundy, J.A. Campbell, K. de Quieroz, D. Frost, D.M. Green, R. Highton, et al. 2003. Scientific and standard English names of amphibians and reptiles of North America north of Mexico: Update. Herpetological Review 34: 196-203.