Louisiana pine snakes (Pituophis ruthveni) are native to the Nearctic region, specifically in the southeastern United States. Their historic range spanned from west-central Louisiana to east-central Texas. However, that range has been fragmented and their current range consists of disjunct populations in parts of Louisiana and Texas.
There are two known populations of Louisiana pine snakes in Texas: one in the Angelina National Forest and one in Newton County. There are four known populations from different parishes, or counties, in Louisiana: one in Bienville Parish, one in Vernon Parish, one in Natchitoches Parish, and a population extending between Vernon and Sabine Parish. There have also been reports of individual Louisiana pine snakes in Rapides Parish, Louisiana and Tyler County, Texas, but the presence of populations in these areas has not been confirmed. ("Biological Assessment and Conference Opinion for the Working Lands for Wildlife Program – Louisiana Pinesnake", 2017; Gibbons and Dorcas, 2015; Hammerson, 2007)
Louisiana pine snakes are frequently associated with longleaf pine (Pinus palustris) forests, but also inhabit shortleaf pine (Pinus echinate) savanna areas. They generally inhabit open pine forests on well-drained, sandy soils. The areas they inhabit are typically fire-maintained vegetative associations, often with dense, grass-dominated understories. Louisiana pine snakes occasionally climb trees but spend much of their time underground or foraging aboveground. They have been reported at elevations between 31 and 153 m above sea level. They are most active from March through November, when aboveground temperatures are optimal for activity.
Louisiana pine snake habitat varies across their geographic range. In Texas, suitable sites include oak (genus Quercus) woodlands, second-growth forests, sandhills, grasslands, or agricultural areas. Typically, they inhabit sandy, open woodlands with relatively high levels of understory vegetative clutter. In Louisiana, these snakes are restricted to longleaf pine forests and second-growth longleaf pine-blackjack oak (Quercus marilandica) vegetation associations.
Louisiana pine snakes spend much of their time underground in abandoned burrows, which are excavated by Baird's pocket gophers (Geomys breviceps). Louisiana pine snakes use burrows when they are inactive, when they enter brumation, and to escape wildfires. Baird’s pocket gophers also serve as a main food source for Louisiana pine snakes. (Gibbons and Dorcas, 2015; Hammerson, 2007; Pierce, et al., 2014; Sperry, et al., 2021)
Louisiana pine snakes are non-venomous constrictors. They have keeled scales, undivided anal plates, and pointed snouts. Louisiana pine snakes have light yellow or tan coloration with dark brown blotches on their dorsal sides. Their dark blotches become more separated and well-defined towards their posterior ends, whereas they have more continuous dark coloration towards their anterior ends. Their heads are almost entirely dark brown or black with no noticeable markings. However, some individuals have a light bar immediately posterior to each of their eyes.
As adults, Louisiana pine snakes range from 122 to 142 cm in snout-vent length (SVL), although the largest reported individual measured 178 cm in SVL. Adult Louisiana pine snakes range from 4 to 8 kg in weight. There is subtle sexual dimorphism, with males larger than females, on average. As juveniles, Louisiana pine snakes are slightly lighter in color than adults, but not strikingly so. Newly hatched Louisiana pine snakes range in SVL from 30 to 58 cm and they weigh an average of 0.023 kg. (Davis, 1971; "Endangered and Threatened Wildlife and Plants; Threatened Species Status for Louisiana Pinesnake", 2018; Gibbons and Dorcas, 2015)
Louisiana pine snakes are oviparous. Hatchlings range from 30 to 58 cm in snout-vent length (SVL) and weigh 23 g, on average. Louisiana pine snakes reach maturity around 3 years old, at which point they range in SVL from 122 to 142 cm.
Louisiana pine snakes exhibit indeterminate growth, although growth rates slow significantly after maturity. They reach 80 to 100 cm in SVL by the time they are one year old and they grow another 20 cm by the time they are two years old. Male Louisiana pine snakes are longer than females, on average. The largest reported Louisiana pine snake was 178 cm long. (Davis, 1971; "Endangered and Threatened Wildlife and Plants; Threatened Species Status for Louisiana Pinesnake", 2018; Himes, et al., 2002)
Louisiana pine snakes are polygynous, with males competing for access to females. Sexually mature females release pheromones to attract males. Prior to copulation, males and females rub their bodies together and align their cloacas. Males then evert a pair of reproductive organs, called hemipenes, and insert them into the cloaca of their mate. Males may also bite females near their necks to prevent escape. (Gibbons and Dorcas, 2015; Himes, et al., 2002)
Louisiana pine snakes breed annually, from April through June. Females gestate eggs for an average of 21 days. Louisiana pine snakes are oviparous and lay 1 to 5 eggs per clutch. Females have been reported to lay eggs in nests shared by other individuals, although they are also known to establish solitary nests. Eggs incubate in nests for up to 60 days. Newly hatched Louisiana pine snakes range in length from 30 to 58 cm and weigh 23 g, on average. Both sexes reach sexual maturity about 3 years after hatching. (Gibbons and Dorcas, 2015; Himes, et al., 2002)
Louisiana pine snakes exhibit little parental investment. Females establish a protected nest site for their eggs but provide no care beyond the act of egg-laying. Males provide no parental care beyond the act of mating.
Female Louisiana pine snakes gestate their eggs for around 21 days before laying them. They lay 1 to 5 eggs per clutch. Juveniles are immediately independent upon hatching. (Himes, et al., 2002)
There is limited information regarding longevity for wild Louisiana pine snakes. A study from 2002 found that, of 30 wild Louisiana pine snakes studied across 2 years, there was a 50% annual mortality rate per year. However, the estimated mortality rate was higher for juveniles than for adults.
Louisiana pine snakes are kept in captivity, but lifespans of captive individuals are not well reported. However, there are reports of captive gopher snakes (Pituophis catenifer) living up to 33.8 years old. It is possible that Louisiana pine snakes have similar captive lifespans, since the two species are closely related. (Himes, et al., 2002; Myhrvold, 2015; Snider and Bowler, 1992; Xiao, et al., 2004)
Louisiana pine snakes are endothermic and bask on warm surfaces to maintain a sufficient body temperature. A study from 2004 found that Louisiana pine snakes retreated to underground burrows when ambient temperatures exceeded 35 °C. They are mostly inactive between late fall and spring. Louisiana pine snakes are most active in spring and summer. They spend more than half of their active hours underground but are active aboveground during the day. They are partially arboreal, climbing on low bushes and small trees.
Louisiana pine snakes are primarily diurnal, although they also exhibit crepuscular activity. A study from 2004 found that Louisiana pine snakes are most active aboveground between 1000 and 1800 h, depending on ambient temperature. They are mostly sedentary, moving less than 10 m daily. However, Louisiana pine snakes are capable of moving long distances. When they do move, they travel an average of 163 m, although they have been reported to move up to 625 m at a time. (Ealy, et al., 2004; Gibbons and Dorcas, 2015; Sperry, et al., 2021)
The individual home range of Louisiana pine snakes ranges from 2.4 ha upwards to 166.83 ha. Substantial movements typically are tied to individuals moving from one pocket gopher tunnel system to another. (Gibbons and Dorcas, 2015; Himes, et al., 2006; Sperry, et al., 2021)
Louisiana pine snakes rely heavily on olfactory cues to perceive their environment. They use their tongues to collect odor compounds from the air and deliver them to their vomeronasal organs, located at the posterior portion of their nasal cavities. Louisiana pine snakes use their vomeronasal organs to detect chemicals released by prey, predators, and conspecifics.
Louisiana pine snakes have dichromatic vision and can detect blue and green wavelengths of light, but their vision is relatively poor. Louisiana pine snakes have no external ears, although they do have internal ear structures closely associated with their jawbones, allowing them to detect vibrations propagating through the ground.
Louisiana pine snakes primarily use chemical and physical cues for intraspecific communication. Reproductively active females release pheromones that males follow if they are interested in mating. While copulating, Louisiana pine snakes maintain physical contact with their mates. In some cases, males bite their mates near the neck to prevent them from leaving. Louisiana pine snakes use acoustic cues for interspecific communication. To intimidate predators, they hiss and mimic rattlesnakes by flicking their tails in vegetation. (Gibbons and Dorcas, 2015; Pierce, et al., 2016)
Louisiana pine snakes primarily feed on Baird's pocket gophers (Geomys breviceps), which also create many of the burrows in which Louisiana pine snakes live. A study from 2012 found that Baird’s pocket gophers comprised an average of 53% of the diets of Louisiana pine snakes, though they also consumed eastern moles (Scalopus aquaticus), hispid cotton rats (Sigmodon hispidus), western harvest mice (Reithrodontomys megalotis), and deer mice (genus Peromyscus). Louisiana pine snakes also eat rabbits (order Lagomorpha), squirrels and chipmunks (family Sciuridae), and other rodents (order Rodentia). Furthermore, they occasionally eat birds and their eggs as well as turtle eggs. The diets of juveniles are similar to adults, although juveniles eat smaller prey items. (Broussard, et al., 2022; Gibbons and Dorcas, 2015; Himes, et al., 2002; Rudolph, et al., 2012)
Natural predators of Louisiana pine snakes include coyotes (Canis latrans), red foxes (Vulpes vulpes), and striped skunks (Mephitis mephitis). They are also eaten by birds of prey. Louisiana pine snakes often hiss loudly and mimic rattlesnakes by moving their tails quickly in vegetation on the ground. Louisiana pine snakes will typically only bite attackers as a last resort. In general, they flee to avoid conflict. (Gibbons and Dorcas, 2015; Himes, et al., 2002)
Louisiana pine snakes consume small mammals, birds, and eggs and may play a role in controlling populations of prey species. Louisiana pine snakes also serve as prey for mammals and birds of prey.
Louisiana pine snakes in captivity are known to serve as hosts for the apicomplexan protist species Cryptosporidium saurophilum. (Broussard, et al., 2022; Gibbons and Dorcas, 2015; Xiao, et al., 2004)
Louisiana pine snakes prey on many small mammals that can damage crops. However, their small geographic range means the effects of their pest control are likely restricted to local communities and do not have any large-scale influence on pest populations.
Louisiana pine snakes are kept in captive breeding programs, with the intention of reintroducing captive bred individuals to wild populations. Research on Louisiana pine snakes in captive breeding programs is beneficial to understanding their ecology and proper captive care for other snake species. (Gibbons and Dorcas, 2015; Himes, et al., 2002; Xiao, et al., 2004)
Louisiana pine snakes have no reported negative economic impacts on humans.
Louisiana pine snakes are listed as "Endangered" on the IUCN Red List and "Threatened" on the U.S. Federal List. They have no special status in the CITES appendices or on the State of Michigan List.
Louisiana pine snakes have a limited range, with only a few disjunct populations scattered across the states of Louisiana and Texas. Their range is restricted because of their dependence on longleaf pine (Pinus palustris) forests, which have declined by around 97% in the past few centuries. Logging of longleaf pines, coupled with fire suppression, makes it difficult for these vegetation associations to regrow naturally. It is estimated that Louisiana pine snakes have only 15% of the habitat they had one century ago. Furthermore, most populations of Louisiana pine snake exist within 500 m of roadways, putting them at high risk for vehicle deaths. Louisiana pine snakes are also killed by humans, either because they are considered pests or because they are mistaken for rattlesnakes. Because they live in small, disjunct populations, Louisiana pine snakes are also threatened by low levels of genetic diversity, which can reduce individual fitness and intensify population decline.
There are some conservation efforts in place for Louisiana pine snakes, though most efforts are generally directed at conserving longleaf pine ecosystems as a whole. Such efforts include replanting longleaf pines and promoting a 2- or 3-year cycle of low-intensity burns. Furthermore, timber harvests in longleaf pine forests are beginning to consider the conservation of gopher burrows and native grass species.
Other conservation practices include reintroductions of Louisiana pine snakes from captive-bred populations into parts of their historic range, such as Grant Parish, Louisiana. Conservation groups are trying to protect habitat and reintroduce Louisiana pine snakes throughout a contiguous range, which would allow for greater connectivity between populations.
Louisiana pine snakes have some populations on military lands and in national forests, which are protected from further habitat loss or conversion. Recently, non-invasive environmental DNA (eDNA) surveys have proven an effective survey method for Louisiana pine snakes, which may improve our understanding of their current distribution and conservation status. ("Biological Assessment and Conference Opinion for the Working Lands for Wildlife Program – Louisiana Pinesnake", 2017; Gibbons and Dorcas, 2015; Hammerson, 2007; Himes, et al., 2006; Katz, et al., 2021)
Kiana Aneli (author), Radford University, Sierra Felty (editor), Radford University, Karen Powers (editor), Radford University, Galen Burrell (editor), Special Projects.
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.
living in landscapes dominated by human agriculture.
having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends. Synapomorphy of the Bilateria.
an animal that mainly eats meat
uses smells or other chemicals to communicate
active at dawn and dusk
animals which must use heat acquired from the environment and behavioral adaptations to regulate body temperature
parental care is carried out by females
union of egg and spermatozoan
forest biomes are dominated by trees, otherwise forest biomes can vary widely in amount of precipitation and seasonality.
Referring to a burrowing life-style or behavior, specialized for digging or burrowing.
the state that some animals enter during winter in which normal physiological processes are significantly reduced, thus lowering the animal's energy requirements. The act or condition of passing winter in a torpid or resting state, typically involving the abandonment of homoiothermy in mammals.
Animals with indeterminate growth continue to grow throughout their lives.
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).
having the capacity to move from one place to another.
the area in which the animal is naturally found, the region in which it is endemic.
reproduction in which eggs are released by the female; development of offspring occurs outside the mother's body.
having more than one female as a mate at one time
communicates by producing scents from special gland(s) and placing them on a surface whether others can smell or taste them
breeding is confined to a particular season
remains in the same area
reproduction that includes combining the genetic contribution of two individuals, a male and a female
uses touch to communicate
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).
Living on the ground.
The term is used in the 1994 IUCN Red List of Threatened Animals to refer collectively to species categorized as Endangered (E), Vulnerable (V), Rare (R), Indeterminate (I), or Insufficiently Known (K) and in the 1996 IUCN Red List of Threatened Animals to refer collectively to species categorized as Critically Endangered (CR), Endangered (EN), or Vulnerable (VU).
A terrestrial biome. Savannas are grasslands with scattered individual trees that do not form a closed canopy. Extensive savannas are found in parts of subtropical and tropical Africa and South America, and in Australia.
A grassland with scattered trees or scattered clumps of trees, a type of community intermediate between grassland and forest. See also Tropical savanna and grassland biome.
A terrestrial biome found in temperate latitudes (>23.5° N or S latitude). Vegetation is made up mostly of grasses, the height and species diversity of which depend largely on the amount of moisture available. Fire and grazing are important in the long-term maintenance of grasslands.
uses sight to communicate
young are relatively well-developed when born
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