Scincella lateralis explained

Scincella lateralis, formerly Lygosoma laterale[1] is a small species of skink found throughout much of the eastern half of the United States, and into northern Mexico. The ground skink differs from the majority of North American lizard species in that it is generally considered a forest dweller.[2] Common names for this species include the little brown skink and the ground skink. However, the common name, ground skink, may refer to any species in the genus Scincella.

Description

The little brown skink is one of the smallest reptiles in North America, with a total length (including tail) of only 3 - 5.5 inches (7.5 - 14.5 cm)and 1 to 2 grams in body mass. Its back is typically a coppery brown color with a white or yellow underside, dark coloration running laterally from eyes to tail [3] and like most skinks has an elongated body and short legs. Transparent disks in the lower eyelids allow it to see with its eyes closed (Beane 2006, Palmer et al. 1995). Females tend to grow faster and be larger than males.[4] Scincella lateralis exhibits sexual dimorphism where the females are generally larger, but males have larger heads. This is suggested that this may be the result of sexual selection favoring larger heads in males in male-male contests.[5] Males heads may also become more orange in color.[6]

Geographic range

The ground skink is found throughout much of the Eastern United States, from New Jersey, Ohio http://www.dnr.state.oh.us/tabid/11846/default.aspx, and Kansas south to Texas and Florida, as well as into northern Mexico, and found along the Atlantic coast[7] This species of skink is one of the most abundant skinks living in southeastern America.[8] More recently, it has been sighted in southern New York State. It has also been seen in isolated regions such as central Illinois.[9] It is absent from higher elevations in the Appalachian Mountains. It is one of the most abundant and widely distributed members of the skink family.[10] Although the geographic range stretches wide, there is little geographic variation within the species.[11]

Habitat

S. lateralis lives in a variety of habitats, including deciduous or mixed deciduous/coniferous forests, hedgerows, palmetto hammocks,[12] and the edges of streams and ponds. It does require a deep substrate, such as leaf litter. Known to occasionally shelter in Sabal palmettos.[13]

Some evidence suggests that meander cutoff may promote gene flow across a riverine barrier in Ground skinks. Several genetic discontinuities align with major southeastern rivers and rivers may have historically isolated populations. However, phylogeographic evidence suggests that some gene flow is occurring across the rivers, and especially the Mississippi River. The meander loop cutoff mechanism may allow passive dispersal to take place across the barrier.[14]

Behavior

The ground skink is a fossorial species, spending the majority of its time buried in leaf litter on the forest floor. Unlike other skinks, it seldom climbs trees. Its usual means of locomotion is to wriggle through the leaf litter with undulating movements. It may dive under water when pursued, although normally avoids wet areas. It is largely diurnal, but may be active at night as well. It hibernates during the coldest months, but may be active in almost any month of the year in North Carolina (Palmer et al. 1995). As befits a tiny lizard, the home range of an individual may be as small as 20 square meters (Natureserve). Ground skinks exhibit tail autotomy when seized which distracts the predator and allows the ground skink to escape. The tail will later regrow.[15] However, once the tail is dropped there is a marked drop in their escape speed (38 to 28 cm/s) and fleeing distance (152 cm with tail, 9 cm without tail).[16] Males are more aggressive than females and are known to bite. Due to males being more aggressive, they often times have a larger head than females. This difference is known as sexual dimorphism and gives the males an advantage when competing for females, attacking larger females, and defending itself from predators.[17] Following confrontation, dominant males will lunge at and chase away subordinate males to secure retreat/hide access.[18] The aggressiveness seen in adults is not shared in neonates, instead they are docile and may share retreats.[19] A field study conducted showed that S. lateralis with lower body temperatures fled earlier in predatory events when the predator was farther away than did warmer animal.[20] Unlike other forest dwelling lizards, S. lateralis is an effective thermoregulator, changing the timings of its activity in response to daily temperature fluctuations and conditions.[21]

Diet

The diet of the little brown skink consists of small insects, spiders, and other arthropoda, such as isopods. The active foraging of a ground skink is assisted by their ability to discriminate prey chemicals and "smells" by tongue-flicking.[22] This is one of their two main methods of locating prey: visual and chemical senses. A visual incentive is associated with tongue flicking, orientation to the prey, and attack behavior.[23] When the visual aspect of the prey is removed, then the amount of tongue flicking increases to an even greater rate.

As prey

Ground skinks are, in turn, preyed upon by snakes such as the eastern racer, ringneck snake, scarlet kingsnake and pigmy rattlesnake (Sistrurus miliarius).[24] Predatory birds of woodland habitats, such as the barred owl and the red-shouldered hawk, also feed upon ground skinks. Even the eastern bluebird has been observed feeding on this tiny lizard (Palmer et al.2008, Robert Brooks 2009). Wolf spiders have also been seen as potential predators, as they are found in the same habitat and utilize similarly limited resources.[25] To prevent predation ground skinks will use their cryptic coloration to hide, if that fails they will run away, as a final defence they will practice tail autotomy or tail dropping.[26] The skink will also fight back and sometimes lunge and chase as a form of defense.[27] They are great at hiding and often use things like leaf litter, logs, and even small holes as cover from predators.[28]

Reproduction

Sexually mature S. lateralis females lay small clutches of 1-6 (usually 2-3) eggs in moist soil, rotting logs, falling logs, or under rocks. Eggs are laid during the summer, March through August in the Southern United States. There may be more than one clutch per year. In contrast to Eumeces species, the female ground skink does not guard its eggs (Robert Brooks 2009). Eggs hatch in one to two months, and young are sexually mature at one year of age. Females generally become sexually mature earlier than males.[29]

Conservation status

The little brown skink is a widespread and common species in most of its range. It is of conservation concern only on the northern edge of its range and can be seen in grassland or forest.

References

Further reading

Notes and References

  1. Brooks, G. R. (1967). Population Ecology of the Ground Skink, Lygosoma laterale (Say). Ecological Monographs, 37(2), 71–87. https://doi.org/10.2307/2937336
  2. Parker . Scott, L. . 2014 . PHYSIOLOGICAL ECOLOGY OF THE GROUND SKINK, SCINCELLA LATERALIS IN SOUTH CAROLINA: THERMAL BIOLOGY, METABOLISM, WATER LOSS, AND SEASONAL PATTERNS . Herpetological Conservation and Biology . 9 . 2 . 309–321.
  3. Brooks, G. R. (1975) Scincella lateralis (Say) Ground Skink. Catalogue of American Amphibians and Reptiles. 169.1-169.4.
  4. Townsend, Akin, J. A., Felgenhauer, B. E., Dauphine, J., & Kidder, S. A. (1999). Dentition of the Ground Skink, Scincella lateralis (Sauria, Scincidae). Copeia, 1999(3), 783–788. https://doi.org/10.2307/1447615
  5. Becker, B. M., & Paulissen, M. A. (2012). Sexual dimorphism in head size in the little brown skink (Scincella lateralis). Herpetol. Conserv. Biol, 7, 109-114.
  6. Becker, Brian M., and Mark A. Paulissen. “SEXUAL DIMORPHISM in HEAD SIZE in the LITTLE BROWN SKINK (SCINCELLA LATERALIS) .” Research Gate, 10 Sept. 2012, www.researchgate.net.
  7. Paulissen . Becker . Sexual dimorphism in head size in the little brown skink (Scincella lateralis)..
  8. Brooks, Garnett R. “Population Ecology of the Ground Skink, Lygosoma Laterale (Say).” Ecological Monographs, vol. 37, no. 2, 1 Feb. 1967, pp. 71–87, https://doi.org/10.2307/2937336.
  9. McAllister, Chris T., et al. “Helminth and arthropod parasites of the ground skink,Scincella lateralis(Sauria: Scincidae), from Arkansas and Oklahoma, U.S.A.” Comparative Parasitology, vol. 81, no. 2, July 2014, pp. 210–219, https://doi.org/10.1654/4682.1.
  10. Brooks, G. R. (1967). Population Ecology of the Ground Skink, Lygosoma laterale (Say). Ecological Monographs, 37(2), 71–87. https://doi.org/10.2307/2937336
  11. Murray, Christopher, et al. “Head shape variation among cryptic populations of ground skinks (scincella lateralis).” Journal of Zoological Systematics and Evolutionary Research, vol. 57, no. 4, Nov. 2019, pp. 877–883, https://doi.org/10.1111/jzs.12314.
  12. Brooks GR (1975) Scincella lateralis (Say) Ground Skink. Catalogue of American Amphibians and Reptiles. 169.1-169.4.
  13. Brooks GR (1975) Scincella lateralis (Say) Ground Skink. Catalogue of American Amphibians and Reptiles. 169.1-169.4.
  14. Jackson . Nathan D. . Austin . Christopher C. . 2013-05-02 . Testing the Role of Meander Cutoff in Promoting Gene Flow across a Riverine Barrier in Ground Skinks (Scincella lateralis) . PLOS ONE . en . 8 . 5 . e62812 . 10.1371/journal.pone.0062812 . 1932-6203 . 3642178 . 23658778. 2013PLoSO...862812J . free .
  15. Web site: Ground Skink . 2022-04-06 . herpsofnc.org.
  16. Formanowicz . Daniel R. . Brodie . Edmund D. . Bradley . Patrick J. . October 1990 . Behavioural compensation for tail loss in the ground skink, Scincella lateralis . Animal Behaviour . 40 . 4 . 782–784 . 10.1016/s0003-3472(05)80710-9 . 53271296 . 0003-3472.
  17. Becker, B. M., & Paulissen, M. A. (2012). Sexual dimorphism in head size in the little brown skink (Scincella lateralis). Herpetol. Conserv. Biol, 7, 109-114.
  18. Paulissen M, Myers L (2017) AGGRESSIVE BEHAVIORS AND THEIR EFFECT ON RESOURCE USE BY MALE LITTLE BROWN SKINKS, SCINCELLA LATERALIS. jnah 5–10. https://doi.org/10.17161/jnah.vi1.11915
  19. Mark Paulissen, Katie Fletcher; Lack of Aggressive Behavior between Neonates of Little Brown Skinks (Scincella lateralis). Journal of Herpetology 1 March 2023; 57 (1): 87–91. doi: https://doi.org/10.1607/22-038
  20. Web site: Smith . David G. . Ecological factors influencing the antipredator behaviors of the ground skink, Scincella lateralis . Behavioral Ecology . 15 June 2023 . https://web.archive.org/web/20230502010552/https://academic.oup.com/beheco/article/8/6/622/208229 . May 2, 2023 . 622629 . en . 10.1093/beheco/8.6.622 . Nov 1997 . live . 8 . 6.
  21. Parker SL (2014) PHYSIOLOGICAL ECOLOGY OF THE GROUND SKINK, SCINCELLA LATERALIS IN SOUTH CAROLINA: THERMAL BIOLOGY, METABOLISM, WATER LOSS, AND SEASONAL PATTERNS. Herpetological Conservation and Biology 9(2): 309-321
  22. Cooper . Hartdegen . R . Discriminative Response to Animal, but not Plant, Chemicals by an Insectivorous, Actively Foraging Lizard, Scincella lateralis, and Differential Response to Surface and Internal Prey Cues. . Journal of Chemical Ecology . 1999 . 25 . 7 . 1531–1541 . 10.1023/A:1020880614708. 37713828 .
  23. Nicoletto . Paul F. . 1985 . The Roles of Vision and the Chemical Senses in Predatory Behavior of the Skink, Scincella lateralis . Journal of Herpetology . 19 . 4 . 487–491 . 10.2307/1564202 . 1564202 . 0022-1511.
  24. Farrell, T. M., Smiley-Walters, S. A., & McColl, D. E. (2018). Prey species influences foraging behaviors: Rattlesnake (Sistrurus miliarius) predation on Little Brown Skinks (Scincella lateralis) and Giant Centipedes (Scolopendra viridis). Journal of Herpetology, 52(2), 156-161.
  25. Rubbo, M. J., Townsend, Jr., V. R., Smyers, S. D., & Jaeger, R. G. (2001). The potential for invertebrate–vertebrate intraguild predation: The predatory relationship between wolf spiders (gladicosa pulchra) and ground skinks (scincella lateralis). Canadian Journal of Zoology, 79(8), 1465–1471. https://doi.org/10.1139/cjz-79-8-1465
  26. Smith, D. G. (1997). Ecological factors influencing the antipredator behaviors of the ground skink, Scincella lateralis. Behavioral Ecology, 8(6), 622–629. https://doi.org/10.1093/beheco/8.6.622
  27. Paulissen, Mark, and Laura Myers. “AGGRESSIVE BEHAVIORS and THEIR EFFECT on RESOURCE USE by MALE LITTLE BROWN SKINKS, SCINCELLA LATERALIS.” Journal of North American Herpetology, no. 2333-0694, 29 Mar. 2017, pp. 5–10, journals.ku.edu/jnah/article/view/11915, https://doi.org/10.17161/jnah.vi1.11915.
  28. Paulissen, Mark A. “Spatial learning in the Little Brown Skink, scincella lateralis: The importance of experience.” Animal Behaviour, vol. 76, no. 1, July 2008, pp. 135–141, https://doi.org/10.1016/j.anbehav.2007.12.017.
  29. Web site: Brooks . Garnett R. . Population Ecology of the Ground Skink, Lygosoma laterale (Say) . www.jstor.org . . 15 June 2023 . https://web.archive.org/web/20230429223236/https://www.jstor.org/stable/2937336 . April 29, 2023 . 7187 . en . 10.2307/2937336 . March 1967 . live . 37 . 2.

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