Saturday, July 28, 2012

LOOK FOR: Blue-tailed, Five-lined Skinks


Photo credit: Holly Sparkman
I was on a pretty intense site visit in Greenville, SC for a few days last week, but you know me -- I had an hour off and I ended up on the walking path that goes along the river downtown. A tiny blue-tailed skink ran right across the path in front of a colleague and me. I pointed it out: hey look, a blue-tailed skink. My colleague was astonished: How did you know that? she said.

I don't know. I don't remember learning the blue-tailed skink. But if you ever saw a lizard with a bright electric-blue tail, wouldn't you want to know what it was?

Just one catch: it turns out that "blue-tailed skink" isn't really their proper name. There are two species of skinks in our area that have blue tails when young. Most likely to be seen is the Five-lined skink (Plestiodon fasciatus): they tend to nest on the ground, in leaf litter. Broad-headed skinks (Plestiodon laticeps) also have blue tails for part of their lives, but they tend to hang out in trees (though they may come down to forage).

In both species, though, that blue tail is eye-catching. And it's brightest on the juveniles; the blue fades as they age.

Why would a species evolve to have their young be so visible? The trick is that the tail is a relatively dispensable part of a skink. In fact, if a predator grabs the tail, it will break off, and the skink will escape and grow a new one. So, it's not so much that the blue makes the young visible: it makes the tail visible, and gives the rest of the skink more of a fighting chance.

Skinks lay eggs once a year, and the hatchlings appear in late summer. So keep an eye out for those little blue tails.
Blue tailed skink
Photo credit: Teague O'Mara

5 comments:

Albert said...

I took a photo of adult skinks in 2005, on the trail between the first empoundment at Pennyfield & the river. Click on my name & scroll to the bottom of the linked page. At the time I labeled them as Broadheaded, but close examination of the original later made me think they are adult Five-lined. The adult male is so dramatically different from the juveniles!

Elizabeth | The Natural Capital said...

One of the sources I was looking at talks about having to look at the size and number of scales on the underside of the tail and on the upper lip to positively identify broadheaded from five-lined. At that point I'm happy to just go with the genus!

Dancingfrog said...

For details about differentiating 5-line skinks from broadhead skinks just checkout the August newsletter of the Maryland Amphibian and Reptile Atlas project:
http://marylandnaturalist.org/wp-content/uploads/2011/12/August-2011-Newsletter.pdf
If you photograph the right details, just submit a record to the project and they will determine which skink you saw.

Elizabeth | The Natural Capital said...

cool! Thanks dancingfrog!

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