Category: Notes from the Field Page 9 of 22

A close-up of the hatchling, un-hatched egg, and the remains of the hatched egg, we recently reported on.

It is interesting that even in fairly well-studied species, we can still find new information from chance observations and carefully planned empirical studies. Recent studies have found that brown anole (Anolis sagrei) females favor nest sites that are quite moist. Losos et al. (2003) also found that the eggs of this species can survive being inundated for up to six hours by seawater. Recently we reported on an observation of brown anole eggs that remained viable after being inundated by fresh water due to heavy rains. The difference between the two conditions is, since seawater is more saline than the content of the eggs, it can be expected that the eggs would lose water, while when exposed to excessive fresh water the water gains will exceed losses, and the eggs will swell.

The observations of other researchers and ours suggest that the eggs of A. sagrei are fairly tolerant to a wide variety of environmental conditions and can remain viable when exposed (for a few hours) to excessively wet conditions. Our observations in Taiwan also reveal that unless washed away or damaged, the eggs of A. sagrei can remain viable during the high rainfall (often as a result of typhoons) of this region.

As Aristotle (384 BC – 322 BC) said, “In all things of nature there is something of the marvelous.” And I would like to encourage everyone to look into their chance observations and to describe them, not only in chat forums, but also in journals as natural history notes. That way the information is not only disseminated, but may also be accessible to a greater audience and for generations to come.

There Is More To That Beach Anole

By Gabriel N. Ugueto

On April 24, 2013

In Natural History Observations, Notes from the Field

Adult male Anolis onca from Isla de Margarita basking.

Continuing the recent interesting post on the Beach Anole Anolis onca, I decided to write something about my personal experiences with this amazing species and attempt to summarize some of what already exists in the literature. Famous by its lack of expanded, smooth, infradigital lamellae, there is a lot more to these beautiful lizard.

Typical habitat of Anolis onca on Isla de Margarita

This “beach” anole is basically endemic to Venezuela (it is also found on a narrow portion of adjacent Colombia). Within Venezuela, Anolis onca has a disjunct distribution (more on that below). It ranges continuously along the coast of the states of Zulia and Falcon in the West. It is also found on the islands of La Tortuga and Margarita, as well as along the coast of the state of Sucre in the East. Another, possibly disjunct population has surprisingly been recorded from dry savannas well inland in the state of Monagas! I have observed A. onca in western Venezuela, but I am most familiar with populations from Isla de Margarita. I have traveled countless times to the island and since I was a kid I always remember being fascinated by these fairly large, active anoles. On Isla de Margarita, A. onca is definitely ubiquitous. It is easily found on thorn scrubland, coastal sand-dune environments, and beaches. It is also common around human habitation. I have always observed this anole in sites with constant and strong wind currents. Several authors have suggested that the windy conditions present in the habitats preferred by this lizard may have prevented it from being strictly arboreal like other anoles (Williams, 1974; Miyata, 1975; Kiester, 1977).

These guys have a really large, beautiful dewlap

Whatever the case, it is definitely more terrestrial than other anoles (even species that are commonly found on the ground, e.g. Anolis planiceps) and I have observed it numerous occasions on open ground. However, it often climbs up to about 1.5 m on shrubs, cacti, vines or rocks. Around human habitation it also perches on unfinished walls of buildings, cobble and fence posts (same places frequented by the larger Tropidurus hispidus on the island). I also have observed A. onca on open sand banks of beaches in close proximity to salt water (Ugueto and Rivas, 2010). Williams (1974) also mentioned finding this species near the seashore. Interestingly, light colored specimens are very well camouflaged amidst the sandy soil. I have noticed that when A. onca perches on low shrubbery it often just exposes its head above the leaves. I do not recall seeing such behavior in other anole species.

Most individuals remain motionless when first spotted. If you get too close for comfort, lizards invariably run towards and hide within nearby bushes, clumps of herbaceous vegetation or thorny shrubs. Occasionally they may hide beneath rocks or boulders. Collins (1971) reported that some specimens escape into Ocypode crab holes after lizards were pursued for long time, but I have never observed this behavior. Various types of small arthropods like grasshoppers, robber flies, beetles and spiders have been reported as prey (Roze, 1964; Kiester, 1977; Ugueto and Rivas, 2010). Kiester (1977) reported that the analysis of 38 stomachs revealed that a particular species of chrysomelid beetle constituted a large portion of the diet in western Venezuelan lizards. Saurophagy has also been reported in this species; Miyata (1975) and Kiester (1977) recorded a large individual preying on a female Cnemidophorus lizard in northwestern Venezuela. I observed this species preying on small flies that passed near the lizard on a beach on Isla de Margarita. Kiester (1977), however described a very interesting mode of predation in which the lizard stalked fast moving robber flies in a cat-like fashion using the irregularities of the terrain as cover and dashing towards prey when at close range. What is known about the reproduction of this species is fragmentary at best, but it appears it could be seasonal on northwestern Venezuela. Kiester (1977) reported females laid eggs after the rainy season so that hatchlings come out during January, February and probably March.

Distribution of Anolis onca and the closely allied Anolis annectens in Venezuela. Notice the disjunct distribution of onca.

As I mentioned earlier, the distribution of A. onca in Venezuela is disjunct and the western and eastern population are separated by a long stretch of apparently suitable habitat.

Anolis conspersus, UV Dewlap Photos And Anoles As House Geckos

By Alexander Stubbs

On April 19, 2013

In Notes from the Field, Research Methods

On a recent trip to Grand Cayman I was interested in the UV reflecting dewlap of Anolis conspersus. The dewlaps of these lizards appear blue to our visual system but are maximally reflective in the ultraviolet. While anoles have 4 cone types (ultraviolet, blue, green and red sensitive), humans have only 3 and cannot see UV light so to understand what these lizards look like in the UV, we have to use specialized camera equipment. The photo to the right shows what a displaying A. conspersus looks like to our camera system when imaged in the human visual spectrum as commercially available digital cameras also have only three channels corresponding to the three human cone types. Presumably if we were also able to see in the ultraviolet as many other animals can, our cameras would be designed with a separate channel for ultraviolet.

These images of the lizard in the UV show clearly the regions of the dewlap and that are highly UV reflective and the pattern of UV reflectance in other areas. One somewhat interesting finding is that while the dewlap scales are highly reflective across the human visual spectrum (which is why they appear white to our eyes) they reflect very little UV light. The lower photo is a monochromatic image (both the red and blue channels in this camera are sensitive to UV so the raw image appears purple) that makes it a bit easier to see brighter areas as white. Note how bright the dewlap appears relative to the reflectance standard, when imaged in the human visual spectrum a similar monochromatic image of the dewlap would appear very dark. I believe this shows the potential value of UV photography when studying Anolis dewlap patterns. While the UV nature of the A. conspersus dewlap is uniform, it’s likely that other species have patterns visible in the UV we’ve previously missed. We have also used this UV photography setup in SE Asia to image Draco flying lizards and other species, some of which have patterns that are visible only in the UV band. The goal of this project is to make a camera system with pixel channels similar to the four cone types found in Anolis lizards and birds to image whole organisms and really “see” the patterns organisms experience with their visual system as they would see them. As Anolis visual pigments and their associated oil droplets appear to be fairly conserved, this seems to be achievable.

Another surprise (to me) was the large number of A. conspersus on Grand Cayman using lights at night to feed. I’ve spent many months doing fieldwork in SE Asia and Central America and can’t recall seeing this sort of thing with other diurnal lizard species, but on Grand Cayman it was quite common in A. conspersus. I observed one A. conspersus male chase away a Hemidactylus that got too close to the light, showing that the anoles at least occasionally displaced the group I typically associate with feeding around lights. A check of the literature shows this has occasionally been documented on other Caribbean islands, but as far as I can tell no one has published on this in mainland species. What diurnal lizard species have others observed using lights to feed at night?

Anole Beach Party In Venezuela

By Jonathan Losos

On April 2, 2013

In Notes from the Field

A windy study site on the northwest coast of Venezuela.

All of us who study anoles in the Caribbean share a PR problem: people think we’re partying on the beach all day long. Now, it’s true that that’s exactly what some of my colleagues do (you know who you are, but I’m not naming names), but there’s a problem with this approach: anoles don’t live on the beach! And for that reason, anole researchers generally do not either, at least not during working hours.

The padless foot of Anolis onca. Photo by J. Losos.

As we all know, anoles are characterized by the possession of two characteristics, an extensible throat fan and expanded subdigital toepads. But there are exceptions. The Cuban A. vermiculatus and A. bartschi (two of the finest anoles you’ll ever come across) have no dewlap whatsoever. And one species, A. onca, entirely lacks toepads, not even a hint of subdigital lamellae.

Where am I going with this, you might wonder? The answer is simple. Where do you think A. onca lives? On the beach! Anolis onca is the only beach-dwelling anole, or so it’s said. And for that reason, our South American Little Known Anole Tour (SALKAT) moved from the chilly Andes of Colombia to the smoking hot sealevel of Maracaibo, Venezuela to see what’s up with this species.

Current exchange rate, 6.3 Bolivares (Bs) to the dollar.

A few notes about Venezuela. Well, one mostly. It’s incredibly expensive. Who would pay $10 for a box of Froot Loops? Not even me. Or $9 for a can of Pringles? Ahem, well, it had been a good day. Rental cars cost more than $200/day, if you can find one (when we tried to get one at the Caracas Airport, the six rental car booths had, between them, two cars available). And hotel rooms are exorbitantly priced and also in scarce supply. We were told that the reason for that is that they were full of Cuban workers, sent over by the Castros to help their socialist brothers-in-arms. And, to be honest, the people we encountered–in the airport, at the hotel, etc.–often weren’t the friendliest.

One thing was cheap, though, gasoline. They practically give it away. At one point, we only had 1/4 tank of gas, so stopped at a service station. I went in and bought a can of soda for $2.50, then paid the bill for the gas, which came to $0.60.

Anolis onca. Photo by J. Losos.

Any way, back to A. onca.

Anolis Carolinensis/Porcatus Hybrid?

By Armando Pou

On March 27, 2013

In Notes from the Field

Old male passed over winter, tough overlord

For several years now, I have been noticing that Anolis carolinensis has been making a dramatic comeback in south Florida. In the last five years or so their numbers have exploded. Their resurgence began in the Florida Keys and they have been working their way north, recently reaching south Miami and now entering into central and northern Miami-Dade County. Unlike the original population of carolinensis, which favored rural environments, this new population is bold and holds its own against sagrei, still dominating the trunk-canopy, but ranging all across different ecological niches including completely urban environments (which carolinensis did not). However, these are simply field observations and conjecture on my part. Having said that, my theory is that they are actually a vigorous carolinensis-porcatus hybrid. I believe this not only because of their robust physical constitution when compared with the original carolinensis, but also because some within the population have the scapular ocellus normally found in porcatus while others in the same population do not and many have the white outline (like the old male in the picture), but not the inner dark portion of the ocelli and vice-versa.

Two contenders to take over turf (probably both offspring of old male). Notice one has prominent “eye-spot,” the other (victorious male) does not.

Adventures With Phenacosaurus

By Jonathan Losos

On March 19, 2013

In Natural History Observations, Notes from the Field

Anolis heterodermus. Photo by J. Losos.

Although many generic names have been proposed for species within the anole clade, traditionally only three other than Anolis were widely used: Chamaeleolis, Chamaelinorops and Phenacosaurus. Each of these clades—which at one time were thought to represent early, pre-Anolis derivations from the anoline line—are morphologically distinctive. The former two, Chamaeleolis and Chamaelinorops, need no introduction—they are oddball species that at first pass might not even be recognized as anoles, and that have received a modicum of scientific study. The third clade, Phenacosaurus, by contrast, has been mostly ignored. This is surprising, because at least some species are quite notable morphologically, with head casques, heterogeneous scalation, wild colors, and an all-over prehistoric appearance. Moreover, they live at remarkably high altitudes, at least by anole standards, and have a passing resemblance—some species more than others—to Caribbean twig anoles. Nonetheless, there is almost no literature on the natural history or evolution of these anoles.

Ken Miyata’s 1983 Journal of Herpetology paper is the one exception. In it, he describes the habitat use of A. heterodermus in areas near Bogotá, Colombia. His description paints the species as one that uses narrow perches on bushes and other vegetation, and that is especially plentiful in blackberry bushes. Combined with its short legs, heterogeneous body and head scalation and elongate and compressed body, reminiscent of twig anoles like A. valencienni, one might entertain the possibility that it is in functional terms a mainland twig anole.

A year and a half ago, we reported in AA on our studies of another phenacosaur, the much smaller A. orcesi from Ecuador. Our studies conclusively demonstrated that it is in all respects like a twig anole—behaviorally, it moves extremely slow; ecologically, it is found almost entirely on narrow surfaces; and morphologically, it is a Caribbean twig anole doppelgänger. But in one respect, A. orcesi was a disappointment—it looks just like any old anole, without the wildly prehistoric aspect for which the larger phenacosaurs are renowned. For this reason, it was time to examine another phenac, and what better choice could there be than A. heterodermus, the subject of Miyata’s study, supposedly common near Bogotá, and appropriately wild in appearance?

And so Rosario Castañeda, Anthony Herrel and I converged on Bogotá in late February for just this purpose, joined by Rafael Moreno, a graduate student at Universidad Nacional de Colombia, who has just completed his masters degree research on this species, with one fine paper out and more in the works. Our plan was simple: go to appropriate spots on the outskirts of Bogotá, locate lizards in the vegetation, watch them and record habitat use and behavior, then capture them and bring them back to the field lab to measure sprinting and biting capabilities and to examine their stomach contents.

Expedition To Swan Island I: Overview

By alexiss

On February 15, 2013

In Notes from the Field

The brown booby, one of the denizens of Great Swan Island.

The Swan Islands, three tiny outcroppings of petrified reef jutting out of the otherwise open stretch of water between Cuba, the Cayman Islands, and Honduras, hold one of the least-known populations of Anolis in the Caribbean. A visit by George Nelson in 1912 established that anoles are present on both the larger Great Swan Island (larger is a relative term – the entire island is about 5.5 square kilometers) and Little Swan (which is about half that size). The specimens collected by Nelson were later examined by Barbour at the Museum of Comparative Zoology at Harvard and found to be closely related to A. sagrei – they were designated as a species, A. nelsoni, notable mainly for its exceptionally large size. They were later relegated to a subspecies of A. sagrei by Ruibal.

Aside from a visit by Brad Lister in the early 70s, the anoles of the Swan Islands have been left in relative peace by anolologists. That is, until last December, when I joined a team including Jonathan Losos, Randy McCranie and Leo Valdes Orellana that set out to visit the Swan Islands to learn more about this mysterious member of the anole clan.

Getting to the Swan Islands turns out to me much easier said than done. The island has been uninhabited for decades, except for a handful of rotating members of the Honduran Navy who are stationed there to keep drug smugglers from using the island as a way station. The only way to contact the island is by radio, with the cooperation of the Honduran Navy. The only way to reach the island is by chartering a private plane or boat. And getting permission to fly there required a week of wrangling with the authorities in La Ceiba, Honduras. With the help of local contacts in the police and the intervention of a lawyer, we were ultimately able to get the necessary permission, first from the head of the armed forces for all of Honduras, and then by the heads of the Air Force and the Navy, respectively. Once we had permission, we managed to charter a small plane to the island, stocked up on rice, beans, water and batteries (the islands have no electricity or running water), and were ready to go (minus Jonathan, who couldn’t last out the wait for permits and had to return to the U.S. to grade final papers).

Big Swan Island

Swan Island from the air. Photo by Alexis Harrison.

Our first view of the island from the air revealed rugged cliffs and open beaches, dense forest, and decaying buildings overgrown by vegetation. We landed on the grassy runway that dominates at least a quarter of the area of the larger island and were greeted by seven armed members of the Honduran Navy and one friendly dog. Despite the guns, the Navy was very welcoming and helpfully carried many of our supplies to the main camp, where they had barracks and a kitchen, and where we could work at an indoor picnic table and could pitch our tents. After some minimal unpacking and setting up, we set off to get a feel for the island.

Luxury accommodations, Swan Island style.

The forests in the center of the island are dark and dense.

Miami Anole Safari (Part III)

By James T. Stroud

On January 31, 2013

In Introduced Anoles, Notes from the Field

Firstly, let me start by offering my sincere apologies for the standard of photography you are about to view. As you AA readers have become accustomed to Jonathan’s flowing prose, and other members’ excellent use of modern photographic equipment, I must warn you not to expect either here!

As has been mentioned previously, the IBS Conference was a tremendous success, and firstly huge congratulations must be passed on to (a potential anologist in the making?) Ken Feeley for all the hard work and effort. The lack of talks concerning arguably one of the world’s most studied vertebrate biogeographic systems did not detract from the high levels of anole hunting that ensued over the course of the conference!

After a wonderful afternoon visiting Miami’s most bizarre lizard community, the following day provided an opportunity for conversations to be followed up from the previous night’s conference dinner (as some graduate students’ memories may have appeared a little hazy on Saturday morning). Much of the day was spent wandering around FIU’s Biscayne Bay Campus eagerly trying to find the dozen knight anoles that were promised to us the previous night by resident expert, and thoroughly nice guy, Sean Giery.

Sean has spent the past 3 years observing the A. equestris community on this campus, and has assured me that he will bless AA readers with a synopsis of his eagerly awaited dietary analysis paper in the near future. The day started brightly, with two juveniles being found in close proximity to each other; however with just he and I as the only observers, it was tough to include these individuals in the promised dozen.

Juvenile knight anole found on a horizontal branch ~2m high. Photo by JStroud

At the start of lunch, and confronting the midday heat with the enthusiasm of schoolboys on a day trip, we regrouped with some extra eyes and headed back out to continue on our quest. Although A. sagrei, A. carolinensis and A. distichus were abundant, these were still not the target species. A loud thump behind us saw us all swivel in synchrony, like a troop of sunburnt and slightly dehydrated Michael Flatley fanatics, to be confronted by a rather startled green iguana that had just plummeted 10 feet after submissively losing a dispute to a larger male. The campus had previously been awash with a healthy population of green iguanas; however the big freeze of 2009 reduced this significantly so that the only survivors were those small enough to retreat underground.

Some Field Observations Of Sitana Ponticeriana

By Ambika Kamath

On January 25, 2013

In Notes from the Field

Every now and then we’ve had posts on this blog about non-anole lizards with anole-like dewlaps (e.g. 1, 2). Many agamids have flaps of skin under their throats that begin to resemble a dewlap, but male lizards in the South Asian genera Sitana and Otocryptis have the most “anoline” dewlaps I’ve seen so far. Indeed, some readers were almost fooled by Sitana’s resemblance, in both dewlap and dorsal patterning, to anoles. I spent the summer of 2012 documenting aspects of the display behaviour, morphology, and ecology of Sitana–here are some of my findings

Despite its ubiquity across much of peninsular India and Sri Lanka, Sitana remains relatively unstudied. Individuals across much of the range are classified as a single species, Sitana ponticeriana, despite substantial variation in dewlap morphology. It turns out that there are at least three dewlap variants, which occur, for the most part, in allopatry. Note the gradation in dewlap colouration between the three “morphs.”

Coloured-fanned, intermediate-fanned, and white-fanned male Sitana ponticeriana. Photographs by Shrikant Ranade, Jahnavi Pai, and Jitendra Katre respectively.

Miami Anole Safari II

By Jonathan Losos

On January 21, 2013

In Introduced Anoles, Notes from the Field

Green anoles everywherer in All-America Park. Photo by J. Losos

The International Biogeography Society meeting over, I had part of a day on my hands before leaving Miami. Many opportunities presented themself in the herpetological magnificence that is South Florida, but I couldn’t escape the disappointment in failing to find the Jamaican crown-giant at All-America Park in South Miami two days previous. So into the rental ‘mobile I hopped and quickly traversed the Magic City.

Arriving at the postage-sized park, I immediately ran into South Miami mayor and renowned neuroethologist Philip Stoddard, who happens to live next to the park and keeps an eagle eye on all of its inhabitants. His Honor confirmed that extreme cold of the last several winters had dealt the Jamaican greens a heavy blow, but nonetheless said that he had recently seen several small individuals, indicating that the population was still extant.

A little green like this one was chased by a bark anole. How ignominious! Photo by J. Losos

After accepting a glass of water, I headed into the park on what was a sunny and beautiful day. Anoles (and also peacocks) were extraordinarily abundant, but what caught my attention was the enormous number of green anoles. Those who are concerned that A. carolinensis is disappearing as a result of the introduction of A. sagrei and others need not worry, they’re doing just fine.

Bark and brown anoles were also quite abundant (word has it that Puerto Rican crested anoles are on the move and now are only a few blocks away), and I made several interesting observations,