W is for Whiptails (Shallow Thoughts)

W is for Whiptails

Late summer is whiptail season. Whiptails are long, slender, extremely fast lizards with (as you might expect) especially long tails. They emerge from hibernation at least a month later than the fence lizards, but once they're awake, they're everywhere.

In addition to being pretty to look at, fun to watch as they hit the afterburner and streak across the yard, and challenging to photograph since they seldom sit still for long, they're interesting for several reasons.

For one thing, they're (almost) all female. Most whiptail species are parthenogenic, meaning they reproduce by asexual reproduction: in other words, virgin birth. (Well, virgin egg-laying, anyway.) That's rare in mammals, but not terribly uncommon in reptiles.

There are several species of whiptails in Los Alamos County:

• Plateau Striped Whiptail, Aspidoscelis velox
• Little Striped Whiptail, A. inornatus
• Chihuahuan Spotted Whiptail, A. exsanguis
• Common Checkered Whiptail or Diploid Checkered Whiptail, A. tesselatus
• New Mexico Whiptail, A. neomexicanus

The Plateau Striped Whiptail is apparently the most common, and I'm guessing the stripy whiptails I see most in White Rock are mostly these.

But it's not easy to tell whiptails apart. When they're young, they're all brightly striped, with a beautiful blue tail. As they get older, some of them lose the stripes and develop more of an ocelot-spotted pattern. Some of them keep the blue tail and others lose it. But there's apparently enough variation within each species that it's hard even to make generalizations about whether a striped lizard is an adult or a juvenile. I don't see spotted adults here as often as I see striped whiptails, but they do show up now and then. I've asked for clarification from a couple of reptile experts here, but haven't heard back yet.

Local reptile expert Anthony Sena wrote a fascinating article a few months ago, Lizard Tales, describing the New Mexico Whiptail, and the genetic analysis that concluded that the species arose from the mating of the little striped whiptail and the Western whiptail, A. tigris (which doesn't occur in this area: Western whiptails apparently prefer hotter, lower areas, and are more common in Arizona and southern New Mexico).

But wait, didn't I say earlier that these lizards were parthenogenic? So how do you get hybrids?

Well, one of the parent species, the Western Whiptail (not one of our local species), isn't parthenogenic: it reproduces sexually. The other parent species, the Little Striped Whiptail, is supposedly parthenogenic like most whiptails (though a male Western could presumably mate with a female Little Striped), but they also have some males ... apparently it's complicated.

You can recognize a New Mexico Whiptail by the distinctive wavy central stripe down its back. This whiptail I saw on a hike down the Red Dot trail has a wavy central stripe, so it may be a neomexicanus. Confusingly, many references (including Sena) describe the Little Striped Whiptail as being very similar to the New Mexico Whiptail -- even though the New Mexico Whiptail is spotted, not striped, as an adult. So is a Little Striped Whiptail striped or spotted? No one seems to agree on that.

Even if it's hard to identify particular species, I love watching whiptails, and trying to catch them on camera, as they dart around the yard in late summer. I've collected my best whiptail photos from the past couple of years: Whiptail photos.

Tags: nature, lizard, photography
[ 19:56 Aug 19, 2020    More nature | permalink to this entry | ]