Category: Natural History Observations Page 20 of 34

You might think this picture was taken in New Hampshire, but these are the pine forests of Valle Nuevo National Park, where Anolis shrevei is found

There are many chilling realities associated with global warming. One of the major lines of research in climate change is to understand how organisms will respond to increasing temperatures. Ectotherms such as reptiles are excellent model systems for learning how organisms will be affected by climate warming as their performance (running, jumping, etc.) is so tightly linked to temperature. Research by Ray Huey and colleagues, for example, has shown that increasing temperatures is pushing some lizards to their thermal limits, leading scientists to suggest that some lizards might not be able to take the increase in heat that is expected over the next few decades.

But spending three years working at high elevation in the Dominican Republic has made me wonder a different question – Can lizards take the cold? Beginning around 1,700 meters or so in the DR you begin to enter a strange habitat. At these high elevations the habitat is composed of pine forests that are reminiscent of New Hampshire, and require that you remind yourself that you are, indeed, still in the Caribbean. It is cold up there – near Valle Nuevo in the Eastern Mountains and near Loma de Toro in the Western Mountains the mean winter temperature hovers just above freezing. Even in summer the nights are cold and the crepuscular hours tangibly chilly.

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Photo by Avery Locklear at http://travel.nationalgeographic.com/travel/traveler-magazine/photo-contest/2012/entries/141546/view/. From the National Geographic Traveler 2012 photo contest.

Like they always say, it’s important to take time to smell the bananas.

Avery Locklear provides the back-story: “I saw the banana flower from a distance and approached it. Then I found the anole resting on it, sitting content. I stood there for a few minutes  as it continued to explore the banana flower.
I have so many memories of anoles from when I was younger. I always called them chameleons until several years ago, I looked them up and found more information about them. My grandmother, who lives in Florida, would sometimes find them in the house and would catch them so she could set them free. I always liked to have a look at them before she let them go.
I have lots of photos of them as they are everywhere in Florida.”

You never know where you'll find a two-tailed lizard in the Bahamas

Two-tailed–or occasionally even three-tailed–lizards are not all that uncommon. The way it usually happens is easy to explain. Most lizards can lose their tails and regrow a new one.  The way they do this is that in the middle of each vertebra in the tail is a zone of weakness (called a “breakage plane”), pre-made to easily fracture. At the same point, the muscles are arranged to pull apart, and the blood vessels to easily split and clamp down, losing little blood. When this happen, the signal goes out–don’t ask me how–and new tail construction begins.

But occasionally it doesn’t quite work like this. The tail is only partially broken, and doesn’t come off, but enough is broken that new tail growth begins. The result: two tails, the old, still attached one, and the newly grown one.

Now, one more point: new tails do not regrow the original vertebrae, made of bone. Rather, they grow as one long, cartilaginous rod. So, one can easily tell the new tail from the old one.

In any case, that’s how I understood things. When we caught the beauty pictured above, I thought “let’s x-ray the tail to illustrate how this happens for our viewing audience back home.” And boy was I surprised. Take a close look–both tails are composed of cartilage–no bones there.

Now, you’re probably thinking: “Big whoop. It lost its tail, regrew it, then partially broke the regenerated tail, leading to the production of a second one.” Well, you’re probably right, but it’s not supposed to happen that way. Regenerated tails do not have breakage planes and other adaptations for detachment. They’re not supposed to be lost and regrown. Can anyone explain to me what’s going on here?

BK. Photo by John Rahn

Previous posts (1, 2, 3) have discussed the effect of Curly-tailed lizards (Leiocephalus carinatus) on brown anoles in the Bahamas and elsewhere. To summarize briefly, the effect is this: curly-tails eat brown anoles. Lots of them. The survivors move up into bushes to get away.

Such slaughter may seem of academic interest when it occurs in far-flung Caribbean ports, but soon–already!–Florida denizens can see the carnage up close and personal. The reason: curly-tails have been introduced to the east coast of Florida and seem to be spreading fairly rapidly.

This is all preamble to a series of photographs that AA reader John Rahn has sent in. John lives in Hobe Sound, Florida  (on the coast, north of Miami and West Palm Beach) and enjoys watching and photographing lizards on his back patio. He commented that “I love watching their antics. They are actually quite interesting and are great subjects to practice shooting (photographing).There’s another on my patio (editor’s note: “another” refers to  the A. distichus  he mentioned, along with a photo, in a comment), a girl with great markings and a red head, and this big boy.”

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I think it’s time we had a talk. How do I put this? There’s going to come a time in your life where you start to notice, you know, things around you that maybe you didn’t notice before. You might not fully understand it, it can be confusing, and, well, I just want to make sure you’re prepared. What am I trying to say? Well, er, I’ll just say it. Anole sex. That’s right. That magical event when a male anole and his old lady get together to make sweet love. There have been a some posts recently on the morphology of the male’s one-twig-per-berry genitalia, anole copulation, and Isabella Rossellini. I thought I’d throw my hat into the ring focusing on the behaviors anoles exhibit while copulating, accompanied by a video of mating A. stratulus, a species of Puerto Rican trunk-crown anole.

The video starts out with the male displaying with bobs and dewlap, and moving a lot, appearing agitated. From what I’ve seen in Puerto Rico and the Bahamas, this is classic male anole hallelujah-I-think-I-might-get-lucky behavior. When the camera moves to the female and the male approaches her, you see her adopt a receptive posture. The male does a couple of push-ups, then bites her neck and the act begins.

During copulation both the male and the female bob, and the male displays his dewlap. Displaying during mating is common in anoles, and from the video you can see that these displays, and especially the dewlap, are pretty conspicuous. Which leads me to wonder why in the world they do it? This is brazen behavior. I saw lizard cuckoos and crown giant anoles (A. cuvieri) at this site on a daily basis, and I doubt either of these predators would pass up on a two-for-one meal if they saw it. Displaying seems to greatly increase the risk of an already compromising and thus dangerous pastime. Is it just a correlated response to the excited physiological state that likely accompanies copulation? Are the males and females communicating with each other? Good old-fashioned exhibitionism? David Crews has published some interesting work on anole display and female receptivity, but I’ve never seen anything that explicitly addresses the topic of display during the act of mating.

Anole Annals has a long tradition of promoting knowledge of honorary anoles (e.g., here). A little while ago, we had a post on non-anole dewlaps featuring Otocryptis and now we continue what will become a series of sporadic posts on the Asian branch of the anole fan club (Hey! That was a pun, in case you missed it).

Thanks to Sameera Suranjan Karunarathna’s posting on the Facebook “Professional Herpetologists” page, I’ve become aware of several interesting articles on the behavior of the Asian dewlap-bearing agamid lizard, Otocryptis wiegmannii.

The first paper is on the territorial behavior of this species. The description sounds like anoles in some ways—dewlap deployment is a major feature—but different in others, such as the ability of the dewlap to change colors and the way in which the lizards launch themselves at each other after approaching bipedally. Here’s the heart of the description:

“At once both males ran towards each other bypedally about 1 m and stood by their hind limbs for about another 1 minute (Fig. 3b). After that, there was about 1 m distance between them. During this period they were expanding and compressing their dewlaps rapidly approximately four to six times per minute and kept the dewlap expanded for approximately 1 second. Theirtails were lifted up and they appeared suddenly with black and white bands that became more prominent. The body colour was distinct with yellow, black, white and green. Their heartswere fluttered fast and both lizards breathed deeply.

Struggling

This video doesn’t involve anoles, but contains some of the coolest lizard footage I’ve seen for a while.  You may have seen video of horned lizards (Phrynosoma) squirting blood from their eyes to deter predation by dogs, but this seems to be the first video of them using the same strategy on a bobcat.  Perhaps not surprisingly, Wade Sherbrooke is responsible for setting this up for National Geographic.

Photos by Veronika Holanova

Veronika Holáňová of Charles University in Prague not only studies anoles, but she breeds them in great quantities, including these wonderful Chamaeleolis. The “false chameleons” as they are called are renowned for specializing on eating snails as adults, and here are some of Veronika’s photos of them in the act.

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