Although the breeding season is now winding down for many animals, eggs or young are still showing up in inconvenient or dangerous locations, as was the case when my landlord found two clutches of eggs a couple of weeks ago (July 10).
While cleaning up some building materials around his garage, my landlord picked up a concrete block, finding the first nest under it, with 11 eggs and an adult five-lined skink (Plestiodon fasciatus). He carefully put the block back in place, then picked up a board next to it; under that, he found another skink with five eggs. At that point he asked his wife to call me, as my landlords often do when they find something interesting going on in nature. Always thankful for such alerts, I grabbed my camera and headed down to the garage.
When my landlord turned over the block for me to see the nest, I could see the eggs and adult, which was undoubtedly a female — only the moms stay with the eggs. They wrap themselves around the eggs to protect them from predators and from the elements. And, as with many egg-bearing animals, the moms also turn their eggs regularly to keep the temperature even during incubation. (See a five-lined skink tending her eggs at Wildscreen Arkive; go to arkive.org, and search on “common five-lined skink.”)
Skinks lay their eggs underneath rotted logs, rocks, or similar objects that provide good cover from the elements and protection from predators. The pregnant female prepares the nesting site by digging out a slight depression for the eggs, as was evident with this nest. The eggs were oval and appeared relatively large compared with the mom, who was about six inches long, including the tail. This is because the eggs, about one-half inch long when they are laid, enlarge by absorbing moisture from the nest burrow. This is likely one of the reasons females seek out relatively damp spots to lay their eggs. As with other reptiles, the eggs of skinks are like parchment — thin and easily punctured. Skink eggs are white when they are laid but can change color over time, becoming tan, sometimes mottled, from contact with the nest burrow, as these were, so they were not freshly laid.
While female skinks will fiercely protect their eggs from small predators, in the face of such large intruders, this one was now desperately trying to hide among or under the eggs. After I quickly made some mental notes and took some photos, my landlord carefully replaced the block and we moved on to the nest under the board.
The female under it had a smaller clutch, five eggs, but otherwise the nest, eggs, and mom were similar. She, too, was trying to hide from us, pushing into the dirt and grass at the edge of the nest. I quickly took more photos, and my landlord put the board back over the nest.
The egg clutches of the two skinks were fairly small for their species; clutches usually range from about 15 to 18 eggs. Some may have been damaged or destroyed. The coverings over the nests were heavy enough that only small predators,such as invertebrates or perhaps a small snake, could fit under them. And no large predator had apparently tried to turn them over.
My landlord agreed to holding off on removing the materials covering the nests until I could find out what to do with the moms and eggs. After returning to my house, I emailed some herpetology experts at the Virginia Herpetological Society (VHS) who had helped me identify a skink and salamander a couple of years ago. One of them — biology professor Paul Sattler, in Lynchburg — responded quickly, writing that, in his experience with skinks in central Virginia, he found that skink eggs usually start hatching around the fourth of July. On the basis of this, he figured the eggs should be about ready to hatch up here in the Blue Ridge.
Sattler suggested that, if the eggs need to be moved and we could put them in suitable habitat nearby, the mothers “would probably return to the nest,” which would be the “best scenario.” If the moms didn’t return, the eggs should be retrieved and put in a plastic box with “something like mulch” that could be kept damp, but not so much that fungus will grow and destroy the eggs. If the nest is too dry, “the eggs will desiccate,” he added. When the young hatched, they would not need parental care, so we could “simply remove and release them in the area near cover of some type.”
After relaying Sattler’s information to my landlord, who is interested in nature and is conservation minded, he said he could hold off on moving the block and board until the skinks eggs hatch. Unfortunately, board covering one of the nests was inadvertently removed by a neighbor who helps with construction projects here, and the nest and skink are gone. It’s unclear whether they were there when the board was removed.
While skink moms are good protectors, they will ultimately eat eggs that fail to hatch (waste not, want not, when it comes to protein). And, according to some sources, skinks can eat the shells. They also eat all the eggs, viable or not, if too stressed by predators. They’re not bad moms, just trying to recycle resources so they continue to reproduce in a safer location.
The other nest was still intact, with the mom guarding it, as of last Sunday (July 19), so I’m hoping to get a chance to see the hatchlings, with their bright-blue tails, before they go off on their own.
© 2015 Pam Owen
Born to be blue, but not forever
The bright-blue tails of young five-lined skinks serve as a lure for predators. The tail easily breaks off when grabbed, enabling the rest of the lizard to escape. Eventually, the tail grows back, although there is a cost: it takes a lot of energy to do that and the skink is without this defense during that time.
While it is better for a young, inexperienced skink to lose its tail rather than its life, the downside to having a bright-blue tail is that it also can attract the attention of a predator that might otherwise not notice the lizard at all. That’s probably why the tails of skinks have evolved to fade as the lizard ages and gets better at avoiding predators altogether.