Category: Notes from the Field Page 6 of 22

Image of the 1995 eruption of the Soufrière Hills volcano on Montserrat. Photo from Wikipedia.

On July 18, 1995 something big happened on a tiny little island in the Lesser Antilles. The Soufrière Hills volcano erupted on Montserrat, an island only about 40 square miles in size that is nestled between Nevis, Antigua, and Guadeloupe. The eruption buried the (then) capital city of Plymouth under several meters of ash and pyroclastic flow. More than a dozen nearby towns were also destroyed. Residents in the south of the island had to evacuate, leaving their homes and land behind. Since then, Montserrat has experienced considerable volcanic activity. In fact, when I was on the island in 2010, I witnessed a major dome collapse, an event that was magnificent to see on the ground, and was even observable from space. I’ve spent some time trying to find Anolis lividus, Montserrat’s endemic anole, across the island, with particular focus on finding it in the south, where volcanic impact has been greatest. Montserrat is basically divided in half by the Belham River Valley, a barren bed of ash that effectively separates the habitable north of the island from the more inhospitable south. I’ve spent many hours in the south of the island searching for A. lividus over a few years. In my experience, the lizards were not abundant (if to be found at all) south of the Belham. Granted, access to this region was very restricted, so I didn’t get to spend a whole lot of time there, but I only ever saw two lizards (a mating pair) on a tree in Richmond Hill, a part of the southern half that’s in Zone C. Towns in Zone C are close to the Belham River Valley and are occasionally opened up for visitors when the volcano has been quiet for a while. Currently, Zone C has ‘unrestricted access’, meaning people can visit day and night without an escort. There is also a relatively unexplored portion of Montserrat southeast of the volcano (the South Soufrière Hills) that has plenty of good habitat and is isolated by the rest of the island by the volcano. There have been a few focused expeditions to that part of the island (for example, to collect individuals of Leptodactylus fallax, the ‘mountain chicken’ frog, for a breeding program), but I haven’t been able to get there.

My interest in A. lividus lay mostly in understanding how recolonization works. Can the lizards cross the Belham River Valley, or is it too hot and inhospitable? As access to inner zones increases, will humans mediate transport into the south of the island? If they get there, will they persist? Although I haven’t been to the island in a few years, I remain very interested in the system. I recently received news on Anolis lividus from Nicolas Tirard, a new resident on the island. He had visited Zone C (which is currently open to daytime visitors) and found an individual of A. lividus. Nicolas informed me that he spotted the lizard (a male) on the terrace of an abandoned home in Richmond Hill, which is the same neighborhood where I found lizards almost six years earlier. Nicolas spent about 30 minutes canvassing this area and only found one lizard. For anyone with experience finding anoles in the Caribbean, particularly in the Lesser Antilles, we know that they are generally much more abundant than that. So I would reckon that lizards in Zone C are probably still pretty scant. I wonder if the lizard Nicolas did find descended from previous inhabitants in that area (for example, from the mating pair I observed earlier), or whether there have been more recent dispersal events. He went back on another occasion to St. George’s Hill, which he says is more densely forested than Richmond Hill, and saw three lizards there. When I visited St. George’s Hill a few years ago it was pretty barren, so clearly the habitat is recovering there.

Anolis lividus from Richmond Hill, Montserrat. Photo by Nicolas Tirard.

I asked Nicolas if he thought that humans were transporting the lizards (accidentally or otherwise) to Zone C through increased transit. Nicolas reckons the lizards can get there on their own right now. He says, “I don’t think it is a human-mediated recolonization, even if there is traffic going back and forth, because the vegetation has grown again in the Belham river, and it is probable that anole can now cross it by themselves.” The finding that the Belham is vegetated is interesting – during my visits there it was a hot, barren bed of ash. The only herps I saw there were enterprising iguanas, boldly basking on piles of hot ash. I also saw an iguana on the roof of a house once in Richmond Hill. As the exclusion zone becomes more accessible, I hope that people will try to find A. lividus (and other organisms) there and, hopefully, share their observations with the Anole Annals.

Nicholas shares his observations on his blog. He has also seen a blind snake (Typhlops) and several iguanas in the exclusion zone. Check out his blog for more.

Another image of the male Anolis lividus spotted in Richmond Hill. Photo by Nicolas Tirard.

Previous posts have discussed communal nesting behavior among a number of anole species, whereby females deposit eggs in the same cavity. A new paper by AA‘s own Michele Johnson and friends extends this growing body of observations, stretching all the way back to Stan Rand’s 1967 work. This behavior has been previously reported for the Cuban Twig Anole (Anolis angusticeps) in Cuba, though apparently not in the Bahamas. According to Robinson et al. (2014), at least nine West Indian anole species are now known to engage in communal nesting, with others potentially to be added. AA has also called attention to a tenth mainland species (A. lionotus), described in Montgomery et al. (2011). So these observations bring to mind some questions: what intrinsic factors of a nest cavity draw multiple females to oviposit there? Are female offspring returning to the site in subsequent years to lay their own eggs? Does this behavior vary individually or regionally? Let us know if you have some of your own observations.

Communal nest of Anolis angusticeps on South Bimini. Figure 2 from Robinson et al. 2014, photo by B. Kircher.

A few months ago, I shared with you some of the odder morphological variations my field assistants and I encountered while measuring Anolis sagrei in Gainesville, FL. We went on to measure quite a few more lizards, and saw quite a few more oddities, as well as some fairly gruesome injuries. Here are some of my favourite examples:

1. A far better picture of a doubly-regenerated tail.

2. A jaw injury that resulted in the left and right sides of the jaws being dissociated from each other.

3. A cut hyoid. I imagine this lizard was no longer able to extend his dewlap.

4. A nasty head injury. We saw this lizard three or four more times after we measured him, and his wound seemed to have healed up completely.

5. A brutal leg injury.

6. A male with not only an impressive tail crest but also some nice red tail coloration.

Here at Anole Annals, we can appreciate a good dewlap. In particular, a pair of agamid clades, namely the genera Draco and Sitana + Otocryptis, arguably do extensible throat fans even better than Anolis. But dewlaps are actually found in many other iguanian lizards, covered by AA posts here and here.

Today I thought I’d share a lesser-known dewlap, that of Cophosaurus texanus, known as the greater (greatest?) earless lizard, and a legitimate candidate for best lizard coloration if you ask me. In my experience, these lizards don’t often dewlap, but will occasionally hit you with a few push-ups, and reliably wag their striped tails at you before darting away — though they are upstaged in this latter respect by Callisaurus draconoides. On a recent walk in the Rincon mountains near Tucson, Arizona, I encountered a particularly saucy individual, and thought I would share.

Here’s a series of photos showing a pushup/dewlap combo being delivered. By the way, Cophosaurus texanus are known to display at potential predators (see Dial 1986, American Naturalist 127:1).

Another shot, the dewlap is being retracted here:

As far as dewlaps go, its not the most impressive, but there certainly looks to be some cartilaginous rod action involved, as in Anolis. But wait – notice anything unusual in the above photos? Yes, there looks to be a parasite peeking out through the lizard’s nostril. Here’s a closer look:

Pretty gnarly. I’m not sure what the parasite is, it looks to me like it could be a maggot (hey, speaking of maggots, remember anole throat maggots?). Hope I didn’t just ruin anyone’s lunch!

Anyway, if you’re interested in learning more about Cophosaurus, here is an excellent write-up written by Robert Bezy and provided by the Tucson Herp Society.