There's a rustling in the leaves. You look to see what made the sound, and bam -- a blue streak vanishes into the duff. Was it a snake? A lizard? Was that intense cobalt color even real?
Yes, it was real. The creature responsible for the streak was a lizard called a skink. Now's the time when the newborns hatch, and the intense blue tails of the juveniles are as bright as neon signs.
There are fifteen species of skinks in North America, a small percentage of the 1,200-plus species found worldwide (it's the largest family of lizards). Most species keep their blue tails for the first two years of life; the tails of adults fade to gray or brown. As for why the young skink needs such a gaudy appendage, the standard textbook answer is that predators like birds and mammals will grab first at the bright tail. Because the tail easily detaches, the lizard escapes -- tailless, yes, but at least still alive.
If this strategy is so advantageous, though, why don't adult skinks have blue tails? One possible explanation is that young skinks tend to spend more time above ground where they're subject to more predators. When they become adults, skinks establish territories inside rotting logs or under rocks and spend little time moving from place to place. (To tell the difference between a mature male and a mature female, look for the orange highlights on the male's head.)
Mating takes place in the spring. Then, in late spring, the adult females retreat to burrows or other sheltered recesses, often deep in the ground, where they lay eggs and remain with them until hatching. A female may keep its eggs moist by licking them or otherwise moistening them or it may simply guard the clutch of two to six eggs. When the eggs hatch, adult females and their brightly colored newborns come to the surface to feed on insects and spiders for the summer. The first chill of autumn sends them underground, where they wait until the first warm days of spring beckon them back to the surface.