Biology of Skinks

Skink Basics

The northern prairie skink (Plestiodon septentrionalis) is a reptile. It belongs to a group, or family, of lizards known as the Scincidae (pronounced “skink-i-day”). Skinks are the most diverse group of lizards, with 1200 species worldwide. The northern prairie skink is one of 27 species of skinks in North America. As a group skinks have a typical lizard body form, but have short, indistinct necks, short legs and long tapering tails. Males of most species display orange or red markings during the breeding season. In many North American skinks juveniles have a bright blue tail.

Description

The prairie skink is a small, slender lizard, olive-brown or grayish in colour with alternating light and dark stripes running the length of its body. The belly is light grey. Adult skinks can grow to a length of about 20 cm (about 8 inches), head to tail, but half of that length is usually its tail. Females tend to be a bit larger than males. Juvenile skinks have bright blue tails. The blue colour fades as they reach adult size. During the breeding season adult males develop orange colouration on their heads and throats.

Names Explained

The scientific name for the northern prairie skink is Plestiodon septentrionalis (recently changed from Eumeces septentrionalis). Plestiodon is thought to derive from the Greek: "pleistos", meaning "most, the most or the greatest", "odontos" is from the Greek, meaning "teeth" (thanks to John White for helping out with the etymology). The species name "septentrionalis" is latin for "of the north". So they are the "most-toothed skinks of the north". The etymology of scientific names, their underlying meaning, often seems more art than science, except perhaps to the person that coined the name in the first place.

The word "skink" comes from Latin "scincus" or Greek "skinkos", which was the common name for a of kind of lizard common in Asia and North Africa. The common name for this lizard, "northern prairie skink", is pretty obvious: a skink that lives in northern grassland regions. There is, in fact, a southern prairie skink, too. The two are considered to be subspecies, or different varieties, of the prairie skink. Plestiodon septentrionalis septentrionalis is the northern subspecies (our Manitoba Skink) while Plestiodon septentrionalis obtusirostris (= blunt nose) is the southern prairie skink. The ranges of these two critters are given in the Biogeography section.

Habitat

Habitat for skinks in Manitoba seems to be limited to areas of mixed-grass prairie in sandy soils. (For some background see Manitoba's Mixed-grass Prairie in NatureNorth.com). In the open grasslands the sun can reach and warm the ground. Skinks need this extra warmth as part of their habitat. Many of the native grasses have a tufted growth form (bunch grasses) that provide dense cover for skinks and habitat for the skinks main prey, crickets and spiders. Areas with very sandy soils are necessary for the skinks to construct nests and burrows, especially for their winter hibernation. In human populated areas artificial cover objects, like boards or plywood, are sought-after cover for skinks. Under such cover objects temperatures are favourable, not too hot or too cool, and they often harbour the insects skinks feed on.

Physiology

Skinks, like most reptiles, are "cold-blooded", or more properly "ectothermic". They don't produce their own body heat like "warm-blooded", or endothermic, animals: birds and mammals. Being an ectotherm means you don't have to use up most of the energy you get in your food just to make heat, so skinks can live on far less food than a comparably sized bird or mammal. But it doesn't mean you have to give up being active when temperatures are cool. Like most reptiles, skinks can maintain a fairly warm body temperature (22 - 35 C) during day time by basking or seeking out warmer microhabitats. They can maintain a constant temperature during sunny weather by selecting spots to either warm or cool themselves. In cool, cloudy weather skinks will be less active. At night they will retreat to burrows or bury themselves under the sand and let their body temperatures cool to that of the ground.