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Leptodeira septentrionalisseptentrionalis

By Bruce Gentry

Geographic Range

Leptodeira septentrionalis can be found in North and South America. The northern range boundary of Leptodeira septentrionalis can be found in the southern tip of Texas. Their populations run throughout central America to western Venezuela and northwestern Peru in South America. (Bezy, et al., 2009; Collins and Conant, 1998; Dixon and Werler, 2000; Guyer and Donnelly, 1990; Henderson and Hoevers, 1977; Lee, 2000; Savage, 2002)

Habitat

Leptodeira septentrionalis can be found in a multitude of environments ranging from semi-arid scrub to rain forests. Within it's Texan range, Leptodeira septentrionalis prefers semi-arid, thorn brush habitats with ponds or streams in which to hunt breeding amphibians and their eggs. In Mexico, these snakes have been documented at elevations of up to 1,981 m. (Bartlett and Bartlett, 2005; Dixon and Werler, 2000)

  • Aquatic Biomes
  • lakes and ponds
  • rivers and streams
  • temporary pools
  • Range elevation
    1,981 (high) m
    ft

Physical Description

Leptodeira septentrionalis is characterized by a head that is much wider than its neck and large eyes with vertical pupils that give the common name, cat-eyed snakes. Above, these snakes are tan, buff, pale gold, or pale orange yellow with a distinctive pattern of large to medium-sized, brown, dorsal blotches or "saddles". Body coloration and size of dorsal spots may vary geographically. The crown is dark with a "spearhead" pointed towards the rear. They feature a thin, dark line on the posterior of each eye. The ventral surface is pale orange anteriorly but becomes brighter closer to the tail. Each ventral scale has a dark border. Adults weigh an average 29.1 g and have an average length of 45.7 to 61 cm. There is little sexual dimorphism in this species, but females average slightly longer than males.

Young cat-eyed snakes resemble adults, but have much stronger coloration. Hatchlings measure 22.9 cm in length.

Leptodeira septentrionalis belongs to a special class of snake known as Opisthoglyphous, or rear fanged snakes. The fangs of these snakes are located at the back of the jaw, so the snake has to position its prey in its jaw in order to bite it. The venom of cat-eyed snakes is of relatively low toxicity and is only enough to subdue small prey.

There are several species that may be confused with northern cat-eyed snakes. The brown-banded morphs of ground snakes have thinner heads, a less contrasting pattern, and round pupils. Differences in coloration distinguish southwestern rat snakes which have dark blotches covering the first half of their bodies, and Texas night snakes which have small dorsal spots bordered by a lateral row of smaller spots. (Bartlett and Bartlett, 2005; Dixon and Werler, 2000; Guyer and Donnelly, 1990; Shine, 1994)

  • Sexual Dimorphism
  • female larger
  • Average mass
    29.1 g
    1.03 oz
  • Range length
    22.9 to 98.4 cm
    9.02 to 38.74 in
  • Average length
    45.7 to 61 cm
    in

Development

Leptodeira septentrionalis are oviparous and lay 6 to 12 eggs per clutch. Developing snakes are nourished by a yolk sac for 79 to 90 days at which time they hatch using an egg tooth to break through the outer shell. The egg tooth is lost after hatching. Young northern cat-eyed snakes appear identical to adults but feature much fresher coloration. The snakes will continue to grow throughout their entire lives. (Dixon and Werler, 2000; Lee, 2000)

Reproduction

Little has been studied regarding the mating habits of Leptodeira septentrionalis.

Leptodeira septentrionalis breeds once a year in early spring. Gravid females have been observed from February 11 through May 14. Females lay between 6 and 12 eggs per clutch and the gestation period lasts between 79 to 90 days. The young are 22.9 cm upon hatching. Reproductive age for this species is currently unknown.

Delayed fertilization has been reported in this species. After being captured in the wild, a female laid a clutch of fertile eggs each of the three years kept in captivity. During its time in captivity, this female never came into contact with a male and so must have used sperm from its last mating activity three years earlier. (Dixon and Werler, 2000)

  • Breeding interval
    Northern cat-eyed snakes breed once a year.
  • Breeding season
    Northern cat-eyed snakes breed from spring to summer.
  • Range number of offspring
    6 to 12
  • Range gestation period
    79 to 90 days

Little has been studied regarding the parental investment of Leptodeira septentrionalis. In general, parental care is not well developed in snakes.

Lifespan/Longevity

Lifespan of Leptodeira septentrionalis is unknown.

Behavior

Northern cat-eyed snakes are strictly nocturnal. During the hours of the day, they hide under logs, leaf litter or other vegetative debris. While not being able to climb trees, its long slender body allows it to reach low branches in search of sleeping prey. These snakes are solitary and presumably only come together to mate. They have not been observed defending territories and seem to be a nomadic species. (Dixon and Werler, 2000; Martinez, et al., 2001; Schad, 1964)

Home Range

Leptodeira septentrionalis is not a territorial animal and home ranges have not been documented. (Dixon and Werler, 2000)

Communication and Perception

Leptodeira septentrionalis uses the vomeronasal system to sense the world around it. The vomeronasal system involves the tongue and the Jacobson's organ. Northern cat-eyed snakes will flick its tongue in the air to gather tiny particles which it will rub against the roof of its mouth where the Jacobson's organ is located. The Jacobson's organ is a chemoreceptor that can detect prey as well as pheremones from other snakes.

When threatened, Leptodeira septentrionalis will coil its body and flatten its head in order to intimidate the approaching creature. It may strike the air several times in a threatening manner, but this species will rarely actually bite.

Little is known regarding the reproductive behaviors and associated communications for this species. The presence of chemoreceptors suggests that pheromones play a role in finding or securing a mate.

Like many snakes, northern cat-eyed snakes do not rely heavily on visual stimuli to perceive their environments. In general, snake eyes are more primitive and have limited focusing ability and have trouble perceiving stationary objects. Snakes also feature minimal ear structures and likely lack the ability to hear. Therefor, the hissing and rattling that some snakes emit is meant to deter predators as opposed to communicate intraspecifically. The ear structures they do have are situated near the ground which greatly enhances their ability to perceive vibrations. (Dixon and Werler, 2000; Halpern, 1987; Mattison, 1995)

Food Habits

The primary diets of northern cat-eyed snakes consist of frogs however, it will also consume lizards, toads, salamanders, tadpoles, small fish and mice. If the prey is small enough, the snake will swallow it whole while it is still alive. If it is a larger animal, the snake will position it to the back its jaw and will use its rear fangs to puncture the prey many times so the low-toxicity venom will seep into the wounds and eventually paralyze the prey. These snakes are often found hunting near ponds and rivers with abundant breeding amphibians. Snakes will drill their heads into the egg sack and eat the eggs one at a time.

The diet of northern cat-eyed snakes changes with the seasons. During the dry season, these snakes will start feeding primarily on lizards which remain active throughout the arid conditions. They may also hunt in small puddles where fish and frogs are trapped. Frog mating season often coincides with the rainy season, at which time snakes consume mostly amphibians and their eggs. (Dixon and Werler, 2000; Henderson and Hoevers, 1977; Roberts, 1994)

  • Primary Diet
  • carnivore
    • eats terrestrial vertebrates
  • Animal Foods
  • mammals
  • amphibians
  • reptiles
  • fish
  • eggs

Predation

When threatened, some individuals may strike the air several times in an effort to ward off the predator, but they will rarely actually bite. The primary method of predator avoidance is to run and hide. If it is cornered, it will become tightly coiled and flattened its head to look more intimidating. In order avoid visual-detecting predators, Leptodeira septentrionalis has coloration that is well camouflaged with its environment. A nocturnal lifestyle also helps to avoid being detected while active. Several documented predators include crane hawks, white hawks, collared forest-falcons, roadside hawks, and great black hawks. (Bartlett and Bartlett, 2005; Dixon and Werler, 2000; Martinez, et al., 2001)

  • Anti-predator Adaptations
  • cryptic

Ecosystem Roles

As a predator and prey, Leptodeira septentrionalis impacts many local populations. They are also hosts for many parasites including nematodes of the genus Kalicephalus. (Schad, 1964)

Commensal/Parasitic Species

Economic Importance for Humans: Positive

Leptodeira septentrionalis has no positive affects on humans.

Economic Importance for Humans: Negative

While Leptodeira septentrionalis is venomous, the poison is not harmful to humans. A zookeeper that was bitten by one of these snakes received symptoms no worse than a bee sting. Leptodeira septentrionalis has also been known to stow away in crates containing food or other items, but they cause virtually no damage. (Dixon and Werler, 2000)

  • Negative Impacts
  • injures humans

Conservation Status

Leptodeira septentrionalis is considered threatened in the state of Texas. It inhabits ponds and streams in the Rio Grand Valley, however, the urbanization of this area has caused the habitat of northern cat-eyed snakes to shrink and is threatening to push the species out of Texas. Emphasis on habitat protection or restoration is necessary to ensure the presence of northern cat-eyed snakes in their native, Texan range. Little is known regarding threats to this species in its tropical range, but habitat destruction through deforestation, urbanization, agricultural clearing, and pollution threaten most ecosystems of the region. ("Endangered and Threatened Reptiles and Amphibians in Texas and the United States", 2010; Dixon and Werler, 2000)

Contributors

Bruce Gentry (author), University of Michigan-Ann Arbor, Phil Myers (editor), University of Michigan-Ann Arbor, Rachelle Sterling (editor), Special Projects.

Glossary

Nearctic

living in the Nearctic biogeographic province, the northern part of the New World. This includes Greenland, the Canadian Arctic islands, and all of the North American as far south as the highlands of central Mexico.

World Map

Neotropical

living in the southern part of the New World. In other words, Central and South America.

World Map

carnivore

an animal that mainly eats meat

chemical

uses smells or other chemicals to communicate

cryptic

having markings, coloration, shapes, or other features that cause an animal to be camouflaged in its natural environment; being difficult to see or otherwise detect.

delayed fertilization

a substantial delay (longer than the minimum time required for sperm to travel to the egg) takes place between copulation and fertilization, used to describe female sperm storage.

desert or dunes

in deserts low (less than 30 cm per year) and unpredictable rainfall results in landscapes dominated by plants and animals adapted to aridity. Vegetation is typically sparse, though spectacular blooms may occur following rain. Deserts can be cold or warm and daily temperates typically fluctuate. In dune areas vegetation is also sparse and conditions are dry. This is because sand does not hold water well so little is available to plants. In dunes near seas and oceans this is compounded by the influence of salt in the air and soil. Salt limits the ability of plants to take up water through their roots.

fertilization

union of egg and spermatozoan

heterothermic

having a body temperature that fluctuates with that of the immediate environment; having no mechanism or a poorly developed mechanism for regulating internal body temperature.

indeterminate growth

Animals with indeterminate growth continue to grow throughout their lives.

iteroparous

offspring are produced in more than one group (litters, clutches, etc.) and across multiple seasons (or other periods hospitable to reproduction). Iteroparous animals must, by definition, survive over multiple seasons (or periodic condition changes).

native range

the area in which the animal is naturally found, the region in which it is endemic.

nocturnal

active during the night

nomadic

generally wanders from place to place, usually within a well-defined range.

oviparous

reproduction in which eggs are released by the female; development of offspring occurs outside the mother's body.

pheromones

chemicals released into air or water that are detected by and responded to by other animals of the same species

rainforest

rainforests, both temperate and tropical, are dominated by trees often forming a closed canopy with little light reaching the ground. Epiphytes and climbing plants are also abundant. Precipitation is typically not limiting, but may be somewhat seasonal.

scrub forest

scrub forests develop in areas that experience dry seasons.

seasonal breeding

breeding is confined to a particular season

sexual

reproduction that includes combining the genetic contribution of two individuals, a male and a female

solitary

lives alone

tactile

uses touch to communicate

temperate

that region of the Earth between 23.5 degrees North and 60 degrees North (between the Tropic of Cancer and the Arctic Circle) and between 23.5 degrees South and 60 degrees South (between the Tropic of Capricorn and the Antarctic Circle).

terrestrial

Living on the ground.

tropical

the region of the earth that surrounds the equator, from 23.5 degrees north to 23.5 degrees south.

venomous

an animal which has an organ capable of injecting a poisonous substance into a wound (for example, scorpions, jellyfish, and rattlesnakes).

vibrations

movements of a hard surface that are produced by animals as signals to others

visual

uses sight to communicate

References

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Collins, J., R. Conant. 1998. A field guide to reptiles & amphibians: eastern and central North America. New York: Houghton Mifflin Company. Accessed February 22, 2010 at http://books.google.com/books?hl=en&lr=&id=32Rm7c-v_McC&oi=fnd&pg=PP23&dq=%22Leptodeira+septentrionalis%22&ots=gsliu5IzbA&sig=T5mEcfmIpJuwkctL0ZtdcMV3nqQ#v=onepage&q=%22Leptodeira%20septentrionalis%22&f=false.

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McDale, L., C. Guyer. 1994. La Selva: ecology and natural history of a neotropical rain forest. London: The University of Chicago. Accessed February 22, 2010 at http://books.google.com/books?hl=en&lr=&id=-uhm7QndX6gC&oi=fnd&pg=PA210&dq=%22Leptodeira+septentrionalis%22&ots=QAi0Q6ytcH&sig=MKiYVo2Qn5yll2wePH4lLMVa1Ec#v=onepage&q=%22Leptodeira%20septentrionalis%22&f=false.

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Roberts, W. 1994. Explosive Breeding Aggregations and Parachuting in a Neotropical Frog, Agalychnis saltator (Hylidae). Journal of Herpetology, 28: 193-199. Accessed February 22, 2010 at http://www.jstor.org/stable/1564620?cookieSet=1.

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