Category: Natural History Observations Page 24 of 34

During our recent visit to Veragua, a few of the hardier participants decided to forego ziplining in favor of a hike. While traipsing through a beautiful stream, we encountered several A. oxylophus, one of the so-called aquatic anoles. Despite the moniker, aquatic anoles do not spend most of their time in the water. Rather, they perch on vegetation or rocks along stream edges, close to or above the water. While at least one species of aquatic anole, A. vermiculatus, actively hunts for aquatic prey, the diets of most aquatic species, including A. oxylophus, comprise nonaquatic invertebrates. All aquatic anoles, however, use the water for escape: when threatened by a predator, aquatic anoles dive into the water and either flee, by swimming or running across the water to the opposite bank, or submerge underwater until the threat goes away. Previous reports suggest that A. oxylophus uses the latter two strategies.

How long did this strapping A. oxylophus stay underwater? Photo courtesy of Alexis Harrison.

Portion of the Dewlap 100% Transparent!

By Yoel Stuart

On March 29, 2012

In Natural History Observations, Notes from the Field

During our Anolis distichus work in the DR last summer, we found one male who had a portion of his dewlap that was completely transparent!

Holey dewlapped Anolis distichus from near Higuey

Of course, there was a hole in his dewlap. (Sorry Manuel).

It’s fairly common to find male anoles with damaged dewlaps. Sometimes there’s a hole punched through like the individual pictured here. (Did he snag it on a thorn? Was he pecked at by a bird?) Other times, the hyoid process is broken such that the dewlap doesn’t fully extend, if it extends at all. Yet these males often successfully hold territories that include females.

A previous post on AA asked, “What’s all the fuss about dewlaps?” Link to that post to read about research that experimentally reduced or disabled the dewlap to study the consequences. These studies did not find an appreciable effect of a disabled dewlap on the outcome of male-male battles (staged in the lab) or on copulation success (measured in the field after dewlap manipulation). These results suggest, counterintuitively, that dewlaps may not play a large role in reproductive success.

Enormous Dewlaps, Mainland-Style

By Jonathan Losos

On March 23, 2012

In Natural History Observations

Anolis chloris. Photo by Luke Mahler

A recent post extolled the size of the dewlap of the Hispaniolan A. christophei, but a number of readers, myself included, suggested that to find a truly humongous dewlap, you need to go to the mainland. And all one needs to do is look at the wondrous A. chloris pictured above to see that that is true. I challenge any Anole Annals reader to show me a photo of a Caribbean anole strutting his stuff so gynormously.

Still don’t believe me? Here are a few more.

Left to right, top row: unidentified Central American anole (ID, anyone?) from http://rhamphotheca.tumblr.com/post/1322893581/male-anolis-lizard-displaying-dewlap; A. polylepis from http://en.wikipedia.org/wiki/File:Anolis_polylepis,_Costa_Rica.JPG Steven J. Johnson; bottom row: A. gemmosus from James Christensen's spectacular flicker site, http://www.flickr.com/people/primevalnature/; unidentified anole from http://www.morley-read.com/frogs_on_line/telimbela/lizards/source/dscn8660.html; and A. frenatus also from Christensen's flickr site.

As far as I’m aware, no one has conducted a quantitative study to compare dewlap sizes among mainland and Caribbean anoles. Sounds like a good project for someone!

More importantly, though, why do the largest dewlaps occur on the mainland? Perhaps it has something to do with the relatively low population densities and low rates of display of mainland anoles? Another project waiting to be conducted.

What Species Is It?

By Jonathan Losos

On March 20, 2012

In Natural History Observations

Female (on left) and male (on right). Tough one. Good luck. Check back for a hint in a few days if no one nails it.

5 Anole Morning At La Selva

By Jonathan Losos

On March 11, 2012

In Natural History Observations

Anolis capito, the pug-nosed anole. Photo by Greg Mayer from http://whyevolutionistrue.wordpress.com/2009/08/23/summer-reading-and-summer-vacation-anoles/

What better way to start off a spring break herpetology class field trip than to go anole hunting? And what a success it was! There has been concern in recent years that the herpetofauna at the fabled La Selva Biological Station in Costa Rica has been declining, but we found no shortage of herps this morning–helped, no doubt, by ample rain yesterday. Anolis humilis and A. limifrons were extremely abundant, as were strawberry poison arrow frogs and, surprisingly, night lizards. A number of A. lemurinus, beautiful red dewlap and all, were spotted, and at a stream, a trio of aquatic anoles, A. oxylophus. The highlight of the morning, however, was finding a female A. capito in its traditional spot half a meter up a tree trunk. The pug-nosed anole, as it is called, is always cryptic, and seems to have become less common in recent years, but this is our second in 24 hours, as another was found during a night walk last night.

And that was just the morning. Going for the double hat trick today, all eyes will be out for the emerald green A. biporcatus. It’s very overcast, which may work against us finding this sun-loving crown dweller often seen high in trees on sunny days. Of course, the Holy Grail of La Selva anolology is A. pentaprion, the twig anole rumored to frequent narrow branches in the canopy, and very rarely seen. But with 26 pairs of herpetological eyes on the lookout, who knows what’s possible?

On Sexual Selection in Anolis

By Yoel Stuart

On March 9, 2012

In Classics from the Literature, Natural History Observations

"Fig. 33. Sitana minor. Male, with the gular pouch expanded (from Gunther's 'Reptiles of India')."

In The Descent of Man and Selection in Relation to Sex (1871), Darwin laid out his ideas about sexual selection. Darwin believed that sexual selection was distinct from natural selection; while natural selection operates through survival and fecundity, sexual selection operates through differences in mating success among individuals.

The puzzle that Darwin set out to solve was the existence of traits like the peacock’s tale or the elk’s antlers. These traits differ between sexes but aren’t related directly to mating. And, these traits appear to be quite costly. Darwin reasoned that these costly traits must benefit the bearer in some way related to mating success. Most likely, these benefits accrued during battle with other members of same sex for mates or during the courtship of the opposite sex. In both cases, having the costly trait benefitted an individual’s mating success beyond the incurred survival or fecundity cost.

Now, how does this discussion relate to anoles?

Crouching Anolis, Hidden Dragon: The Stunning Sequel to Clash of the Anole Titans

By Jonathan Losos

On March 5, 2012

In Natural History Observations

Clash of the Anole Titans

From the author of “Clash of the Anole Titans” comes this poetic tale of youth redeemed, power lost, and grace under pressure. Don’t miss it.

Knight Anole Eating a Bird!

By Jonathan Losos

On February 26, 2012

In Natural History Observations

Knight anole eating a bird! Photo courtesy of Paul Richards.

In their recent paper on home range of A. equestris, Nicholson and Richards reported on a knight anole consuming a migrating blue-gray gnatcatcher. Here are the full details, in the words of Paul Richards:

“Kirsten Nicholson and I were attempting to resight one of our radio transmitter equipped A. equestris. Resighting transmitted individuals was difficult as they are hard to see even when we have a clear signal. We would regularly spend 15-20min search, and have a 50% change of resighting a transmitted individual (or less, I cannot remember – but we can probably estimate this from our notes). I saw a Blue-gray gnatcatcher land on a branch right in our general search area that was about a 2m diameter zone of the canopy of a small tree at about 3-5m height. I looked away continuing the search and seconds later I heard an alarm call, looked back to the spot and saw the A. equestris in the picture with the bird in its mouth. This A. equestris was unmarked, and I do not recall ever resighting the transmitted individual that we detected in the area. We can check our notes but I think it took at least 20min for this A. equestris to finish eating the gnatcatcher. I recall in using the branch to wipe/swipe its jaw across, one side the the other, repeatedly, to help get the bird in its mouth.”

Information on Anolis Maynardi (AKA The Little Cayman Green Anolis)

By Pat Shipman

On February 17, 2012

In All Posts, Natural History Observations, Notes from the Field

My husband and I are retired professors living part-time on Little Cayman, so we have come to know both A. sagrei and A. maynardi fairly well. Due to the dearth of information on the latter, we’re posting whatever we’ve got in hopes it helps someone or inspires someone. We have one, a large male, who sleeps most night on a ledge on the inside of our screen porch (he comes in a gap under the door). He goes to bed about 5:30-6 and wakes up around 8 am.

Anolis who sleeps on top of screen door frame

He is very regular in his habits & quite territorial — we watched him chase a smaller green anolis out of his sleeping ledge with much head bobbing and charges and this morning he smacked into another large male who had the affrontery to be sitting on his deck outside the screen porch! The other male either jumped off the deck or moved quickly to be underneath the deck.

We attach a few photos of two maynardi mating yesterday. Total encounter time was about 6 minutes.