Common Five-Lined Skink

Description

Adult common five-lined skinks range from 12.5 to 22.2 cm in total length. They have an elongated, flattened body, four moderately sized legs and a long tail. Like all lizards, common five-lined skinks have scales, movable eyelids and external ear openings. The scales are smooth, giving them a shiny appearance. Relatively long toes and claws make them excellent climbers. Hatchlings and juveniles are black with a vibrant blue tail and five white, yellow or cream-coloured stripes that run from the snout to the tail. The colours fade as individuals age, and older adults have nearly a uniform grey, brown or bronze colour. However, the stripes are often still visible in adults, and females retain more of the juvenile colouration than males. Adult males have broader heads than females, and their lower jaw and chin are bright orangish-red during the breeding season.

Distribution and Habitat

The common five-lined skink’s Canadian range is restricted to Southern and South-Central Ontario, where it is found along the southern edge of the Canadian Shield from the eastern shore of Georgian Bay east to Mallorytown near the St. Lawrence River. Common five-lined skinks can also be found in several small, isolated locations in the Carolinian region near Lake Erie, Lake St. Clair and Lake Huron. This species is widespread throughout the Eastern United States, from Vermont south to Florida and west to Minnesota and Texas.

In Canada, common five-lined skinks live in open-canopy habitats (i.e., less than 50–60 per cent canopy cover). In the Carolinian zone, they are typically found in open woodland, savannah, prairie, stabilized dunes, and human-modified areas such as old fields and clearings around buildings. Individuals on the Canadian Shield usually live in rock barrens surrounded by forest and wetlands ecosystems. A key habitat requirement is a suitable cover that protects from predators and provides the necessary thermal conditions. Woody debris is the most commonly used cover in the Carolinian zone, while individuals living on the Shield primarily depend on loose rocks and rocky crevices for shelter. Females also nest under cover. During the winter, common five-lined skinks burrow into the soil or use mammal burrows, rocky crevices, or other underground features to get below the frost line and avoid freezing temperatures. Five-lined skinks have small home ranges, with sizes ranging from 34 m² to 1,422 m² in Canadian populations.

Did you know?
As ectotherms (animals that don’t generate their own body heat), temperature has a major influence on where common five-lined skinks can live. In Canada’s cold climate, common five-lined skinks are largely restricted to open-canopy habitats that receive ample sunlight and provide lots of basking opportunities. They even select cover objects within these environments based on their thermal properties. Conversely, where temperatures are warmer in the US, common five-lined skinks live in the forested habitats.

Reproduction and Development

Common five-lined skinks mate in the spring. Females lay a single clutch of eggs each year, typically between late June and mid-July. On average, there are 9–10 eggs per clutch. The female remains with the eggs throughout their incubation, which typically lasts four to six weeks. During this time, she protects them from predators and occasionally rotates them to maintain ideal temperature and moisture levels. The eggs hatch in late July to mid-August, and the hatchlings are roughly 5.8 cm in total length. Juveniles reach maturity in one to two years but likely do not reproduce until after their second winter. Individuals can live for nine or ten years, although most do not live for more than five or six years in the wild.

Diet and Predation

Common five-lined skinks are diurnal, meaning they are most active during the day. They eat a variety of invertebrates, but spiders, grasshoppers and cockroaches make up a large part of their diet. Predators of the common five-lined skinks include a wide range of small- to medium-sized mammals (such as shrews, weasels, skunks, raccoons and foxes), birds (such as crows and hawks), snakes, spiders and even fish. Like many other species of lizards, common five-lined skinks may drop their tail when threatened by a potential predator. This is known as “tail autotomy.” The tail continues to wriggle after being dropped and can distract the predator while the rest of the lizard escapes. Although the tail will eventually grow back, dropping its tail can also have negative consequences for the lizard, such as reduced survival during hibernation.

Threats

Habitat loss and fragmentation, particularly from housing and cottage development, is a threat to the common five-lined skink throughout its range. The removal of woody debris, rocks and other cover is another significant threat that reduces habitat quality and can cause population declines. Roads cause the direct mortality of individuals and can create barriers to movement. The danger of roads is especially high in the Carolinian zone, where road densities and traffic volumes are among the highest in Canada. Climate change is also a serious threat to five-lined skinks in the Carolinian zone; increases in the frequency and severity of storms and floods are increasing shoreline erosion and reducing the amount of habitat available to this species. When these severe weather events occur during the winter, they may also cause the death of hibernating skinks. Other threats to the species include increased predator abundance (e.g., raccoons) in many human-settled areas and a succession of open-canopy habitats due to fire suppression.

Status and Conservation

Globally, the common five-lined skink is listed as least concern by the International Union for Conservation of Nature. The common five-lined skink (Carolinian population) is listed as endangered under Canada’s Species at Risk Act, while the Great Lakes/St. Lawrence population is listed as special concern. The widespread conversion of natural habitat into urban and agricultural land uses has resulted in the loss of the common five-lined skink from much of its historical range in the Carolinian zone. In that region, the species has been reduced to a handful of small, isolated populations largely restricted to protected areas. Although these populations are protected from some threats (e.g., habitat loss), considerable work is still required to address remaining threats, such as road mortality and increased predator populations. While threat management is also important on the Shield, a paradigm shift away from large-scale conversion of wilderness areas into human-modified landscapes is crucial to the long-term survival of that population and many other species at risk in that region.