Overview
The Florida Keys mole skink is a small lizard known to occur only on islands in the Florida Keys. This species is semi-fossorial (adapted to digging and living underground) and cryptic in nature. While it can run, it more often utilizes “swimming” as a method to move through loose substrate. Soil and moisture conditions help define habitat, as skinks are seldom encountered where the soil is not well drained and friable (crumbly in texture). Groundcover, such as leaf litter, debris, or tidal wrack, is also an essential habitat feature that provides protection from predators, moderates extreme temperatures, and attracts their prey.
Threats
The predominant threats currently affecting the Florida Keys mole skink and its habitat are sea level rise, more numerous high tide flooding events (the very highest tides), increased storm surges, and shifts in seasonal patterns of rainfall and temperature, all of which are predicted by climate change climate change
Climate change includes both global warming driven by human-induced emissions of greenhouse gases and the resulting large-scale shifts in weather patterns. Though there have been previous periods of climatic change, since the mid-20th century humans have had an unprecedented impact on Earth's climate system and caused change on a global scale.
Learn more about climate change models. The Florida Keys are low-lying islands with an average elevation of less than 4 feet. Habitat for the Florida Keys mole skink can be degraded or removed due to impacts by extreme events such as floods or storms. Saltwater storm surge and flooding would likely result in displacement landward and the loss of individual mole skinks. These same events could trigger opportunities for skinks to become passively dispersed if carried on rafting debris.??
Florida Keys mole skink habitat is also at risk of loss and degradation due to land uses and human activities, such as land development, human population increase and the resulting habitat disturbance, and beach erosion.
Eggs and hatchlings are susceptible to imported red fire ant (Solenopsis invicta) predation. Fire ants may also indirectly impact adults by affecting survival and weight gain, behavior, foraging patterns and habitat use, and reduced food availability.
The Florida Keys mole skink species may be experiencing predation or resource competition from several invasive lizard species.
Nonnative, invasive plants can make habitat conditions unsuitable for mole skinks by changing or reducing leaf ground cover, increasing root masses in friable soils, loss of shade, changes in soil temperatures, and loss of protective cover.
Scientific Name
Identification Numbers
Characteristics
Habitat
The Florida Keys mole skink has an opportunistic and generalist feeding behavior, preying on whatever is present in the ground cover or soil that is of a size they can ingest. It preys on a variety of small insects and arthropods including ants, crickets, beetles, termites, small bugs, butterfly larva, spiders, mites, pseudoscorpions, and fungus. The make-up of diets shifts seasonally with prey relative to abundance.
Behavior
Florida Keys mole skinks spend most of their time under ground or under groundcover since they are cold-blooded (ectothermic) reptiles and dependent on the air and soil temperature to thermoregulate (maintain body core temperature). Ground cover moderates soil temperatures and provides shade to assist in the skinks’ thermoregulation in hot climates.
Physical Characteristics
Adults are about 5 inches long.
The Florida Keys mole skink is a slender, small lizard colored brown, tan, or grey, with smooth scales and two to four pairs of light stripes extending from the head and neck that may reach the base of the tail. The tail, as in other species of mole skink, is brilliantly colored with variations from orange and red to faded pink. This variation is likely due to age of the animal, as smaller individuals possess more vibrant tails that transition to more subdued coloration as they grow. The small legs have five toes on each foot. Males display ventral and submental (under the chin) patches of pink and orange during the breeding season, although hints of these patches can be apparent throughout the year.
Life Cycle
The Florida Keys mole skink has three life stages: eggs, immature (juvenile), and adult. The immature stage lasts approximately one year from hatching to reproductively mature adult.
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The generation time for the Florida Keys mole skink has not yet been documented. The age at first reproduction for the Florida Keys mole skink and the Florida sand skink (Plestiodon reynoldsi) are similar (24 months compared to 19 to 22 months, respectively) and may suggest a comparable generation time of approximately one generation every three to four years.
Based on work conducted in a laboratory setting with a closely related species, the red-tailed skink (Eumeces [now Plestiodon] egregius), we understand the following:
Scent is the most important factor in finding and selecting mates. Mating of the Florida Keys mole skink typically takes place in fall or winter. Florida Keys mole skink has been observed mating during this time by field biologists surveying for the species. After mating the female enters a period of inactivity that lasts about one month. Eggs are laid under debris and usually in nest cavities. Female mole skinks den and attend their nests annually between April and June. The females lick, turn, and protect the eggs from predators. Research has shown that when any of these activities are prevented, the eggs are at risk of not developing.?
Soils used for nesting are generally dry and unconsolidated to allow for the digging of nest cavities and their swimming movement through substrate. Based on laboratory research, an individual skink lays a clutch of two to 11 eggs with an average of three to five eggs. Eggs incubate for 31 to 51 days. No in-situ nests have been identified for the Florida Keys mole skink. Because of the predominantly limestone, prehistoric coral reef and rocky makeup of the archipelago, only a few areas provide the unconsolidated soils considered preferred by the Florida Keys mole skink for nesting.
Similar Species
Northern mole skink (P. egregius similis),
peninsular mole skink (P. egregius onocrepis)
blue-tailed mole skink (P. egregius lividus)
Cedar Key mile skink (P. egregius insularis)
The Florida Keys mole skink (Plestiodon egregius egregius) is one of five distinct species of mole skinks in Florida, all in the Genus Plestiodon (previously referred to as Eumeces). The northern mole skink is the most wide-ranging and has been documented in Florida, Alabama, and Georgia. The peninsular mole skink occurs throughout Florida. The blue-tailed mole skink is restricted to the Lake Wales Ridge in central Florida, and the Cedar Key mole skink is restricted to the Cedar Key islands in the Gulf of Mexico. The Florida Keys mole skink is more closely related genetically to the blue-tailed mole skink than the peninsular mole skink. However, Florida Keys mole skinks in the upper Keys show morphological characteristics between the Florida Keys mole skink and the peninsular (mainland) mole skink. Recent genetic evidence supports a lack of interbreeding between the Florida Keys mole skink and the other mole skink species.
Geography
The Florida Keys mole skink is endemic to the Florida Keys and has been documented on 23 islands from Key Largo in the Upper Keys to Loggerhead Key of the Dry Tortugas in the Distal Sand Keys. Most islands with current detections occur within the Lower Keys (Bahia Honda Key to Key West), with the largest numbers of detections from Long Beach on Big Pine Key.
Timeline
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