All posts by Jonathan Losos

About Jonathan Losos

Professor and Curator of Herpetology at the Museum of Comparative Zoology at Harvard University. I've spent my entire professional career studying anoles and have discovered that the more I learn about anoles, the more I realize I don't know.

Male Brown Anoles Disperse Farther than Females

sagrei dispersalUnderstanding dispersal—the extent to which organisms move from their place of birth—is of obvious importance in understanding many aspects of the natural history of a species, such as how related individuals are in a population or how genetically distinct one population is from another. Despite the intensive study on Anolis, however, very little is known about their dispersal. This is particularly surprising for species like the green and brown anoles, which are so common in so many places. Now, in a very nice experimental study in Behavioral Ecology, Calsbeek and colleagues have shed light on dispersal in the brown anole in the Bahamas.

Basically, the study went like this: the authors collected a bunch of gravid females from a variety of sites on a single, small island in the Bahamas. They got the lizards to lay eggs in the lab and hatched them out, then released them within three weeks of hatching back on their mom’s island. Each lizard was individually marked. The researchers then returned the following spring to find which animals had survived and how far they had moved. Then, they returned again in the fall to see how these survivors fared over the following summer and whether subsequent survival in this second period varied as a function of the distance they had dispersed in the first period.

There are a lot of interesting specific details and I encourage you to read the paper, but the broader story is this:

1. Males dispersed substantially further than females

2. Surviving males grew faster than surviving females

3. Survival of the lizards was low

4. Among females that survived the first period, those that had dispersed shorter distances survived better in the second period

Surprisingly little is known about the extent of anole dispersal, and so this paper is an important advance. As far as I’m aware, dispersal of only two other anoles have been studied. Here’s a summary from Lizards in an Evolutionary Tree:

“Little is known about the dispersal of anoles. One study of A. limifrons found that most lizards dispersed very little and that the home ranges of many individuals moved little from the juvenile to adult age. The maximum dispersal distance, measured as distance from the center of the juvenile home range to the center of the adult home range, based on 148 individuals, was 45 meters. Both the mean and extremes were greater for males than for females (Andrews and Rand, 1983). Anolis limifrons is a small and short-lived mainland species; it is always possible that larger, longer-lived species may disperse further.

The only other data come from Anolis aeneus, which moves as much as 150 meters or more after hatching to occupy open clearings (Stamps, 1983b, 1990). Ultimately, the lizards move back into shadier areas when they reach subadult size, although it is not known whether they return to the vicinity of their hatching site.

A number of arboreal species are known to disperse across open ground between trees (Trivers, 1976; Hicks and Trivers, 1983; Losos and Spiller, 2005).

How Anoles Respond to Toucans and Other Birds

James Christensen, a fabulous nature photographer and keen naturalist, made the following comment on the recent post about how anoles react to bird calls. However, the points are so important that they deserve a post of their own, so I’m reprinting them here:

I have spent many hours photographing wild anoles, especially here in Ecuador, and have learned a great deal about their behaviour while watching them through the viewfinder. When the wind picks up and begins to stir the surrounding foliage I can expect my subject to risk rapid movement – therefore, I probably won’t get a viable shot. Conversely, when toucans or furnarids become active in the vicinity I know that my anole will not venture an abrupt movement, so I squint through the viewfinder and start clicking the shutter. What I have noticed is that the anoles – e.g. Anolis gemmosus and A. proboscis – react not only to the calls of these birds, but also to the sound of their wingbeats. The usual response is a cessation of movement and an increased watchfulness; the anole sits very still and peers upward while discreetly swivelling its head. In the case of a very fit male A. gemmosus with whom I spent many hours – over a period of several weeks – upon the disappearance of avian predators he would begin to dewlap, frequently ‘emphatically’, seeming to reassert his local dominance in the wake of forced inactivity. It became clear to me that the sounds of nearby birds triggered a profound shift in behaviour, and that vision played a secondary role in the perception of avian threats – as every neotropical birder knows, foraging birds are heard more readily than seen.

Concerning the above study, it perhaps bears noting that the American Kestrel is not a highly vocal bird, and that it is likely to remain silent while hunting. I have frequently observed toucans apparently hunting in shrubby forest margins, where no fruit-bearing trees were evident and anoles were plentiful, and at such times the birds were always silent – only their deep wingbeats would betray them to a wary anole.

New Comprehensive Account of Everything about Tuatara

Alison Cree, one of the leading researchers on tuatara, has written a comprehensive account of everything we know–and would like to know–about toots. The book not only covers ecology, evolution, behavior, physiology and so on, but also the history of knowledge of tuatara as well as details on how they were perceived by the Maori. And, of course, the incredible conservation turnaround, which has led to reintroduction of tuatara to the New Zealand mainland after a half-millenium absence.

This fine volume can be purchased for a tad under US$75 plus shipping from the University of Canterbury Press.

Anole Apartment Invasion: What Can Be Done?

Anole in the house. Photo from Daffodil’s Photo Blog

AA reader Katharine from southern Florida writes:

“I live on the 4th floor of a 4-story concrete constructed condominium building (6 units to a floor) with catwalks in S.E. Fl.  In front of the ground floor walkway of our building there is landscaping & ligustrum trees that reach up to the 2nd floor with catwalks with overhead lights on in front of each doorway at night.

For some reason anole lizards seem to find their way more to my unit (when I open my entrance door they come in) than the others on the same floor all with the same ground floor foliage, trees & overhead lights. One also sees the feces they’ve left overnight in front of my unit and not the others.

It makes me wonder if these lizards travel as ants do, following a leader either by a scent or fluid left by the leader or previous lizard?  I’ve learned that these lizards are attracted both to light (obviously, the catwalk lights) & the greenery.  However,  the other units on the same floor under the same conditions don’t seem to have the same invasion.

I’ve done as much Google researching as I can but can’t seem to find an answer.  Do you have an answer or can you direct me where I can look.?  Obviously, I’m trying to find some way to deter or reroute their path.”

Geckos Eat Rats

gecko eating rat

As lizards go, it’s hard to beat an anole. But geckos come pretty close. Anole Annals, of course, is dedicated to reporting all things anole, but until Gecko Gossip debuts, we feel it’s only polite to occasionally comment on geckonid happenings.

In that light, we were impressed to see the culinary prowess of the Tokay gecko, which apparently quite regularly preys on small rats in the Philippines. Read all about it in Herpetology Notes.

Anole Foraging Mode: New Data

An actively foraging anole on the prowl (A. tigrinus; photo by J. Losos)

An actively foraging anole on the prowl (A. tigrinus; photo by J. Losos)

Nearly 50 years ago, Eric Pianka proposed the idea that hunting animals forage in one of two ways, either actively foraging for prey or sitting-and-waiting for food to wander by. These ideas were initially promulgated with lizards in mind, and much of the research in the last half century has involved lizards. Anoles haven’t been a major player in the work, but their certainly have been some studies conducted on anoles.

This post is motivated by a paper published by Cooper et al. in Herpetology Notes last year in which new data are presented on six anole species, as well as for a variety of other species. The anole data conform both to previous data on the same species and studies on anoles in general: as lizards go, anoles are on the sit-and-wait end of the spectrum, moving relatively little (think about the other end of the spectrum, species like whiptail lizards which seem to move almost non-stop).

I was surprised in looking through the archives to see that we haven’t previously had a post on AA about foraging mode. Now we do! And for some background: I reviewed what we know about anole foraging in a five-page section of Lizards in an Evolutionary Tree. The take-home messages:

1. By comparison to other lizards, anoles don’t move much and would be considered sit-and-wait foragers;

2. Nonetheless, among anoles, some are much more active foragers than others;

3. Caribbean anoles are much more active than mainland species;

4. Much remains to be learned about the specifics of anole foraging and how it differs among species

And here are some highlights, from the footnotes:

“Some of the danger inherent in an active foraging mode was apparent in another observation of a female [A. valencienni] moving upside down on a bromeliad, searching for prey (quoting from Trivers’ field notes, p. 575): “. . . it seems to spot something on a neighboring bromeliad, also upside down. I too spot something on the second bromeliad. Starts to dart the 5 cm to the neighboring bromeliad but—as if forgetting it is upside down—it steps into thin air and falls 6 m to the ground. It appears to be uninjured.”

“Examples of this prey-catching behavior were provided for the relatively short-limbed A. carolinensis (under the name A. principalis) by Lockwood (1876, p. 7): “I have just been watching Nolie eying a fly which was walking on one of the glass panes of his house. He made a noiseless advance of about three or four inches; then followed a spring, when he was seen cleaving to the glass by his feet, and champing the captured fly. I saw him once intently watching the movements of a fly which was walking on the glass. As seemed evident to me by an ominous twitch of that little head, his mind was made up for a spring; but lo, there was a simultaneous makeup of mind on the part of the fly, which at this juncture flew towards the other side of the case. Then came—and how promptly—mental act number two of Anolis, for he sprang as the after-thought directed, and caught the insect on the fly.” Dial and Roughgarden (1995) report an anole jumping from a branch one meter above a spider web, catching the spider as it passed by, before landing in the vegetation below.”

Arthur Loveridge Obituary Written by Ernest Williams

loveridgeArthur Loveridge was one of the great scholars of African herpetology, and a fascinating individual, curator of the Museum of Comparative Zoology for 33 years. AA has recently come across a pdf of his obituary written by Ernest Williams, who succeeded him at the MCZ.

The obituary is fascinating not only because it details the career of an important, yet quirky, individual in our field, but also marks how the profession of museum curator has changed markedly from the days in which curators were wealthy amateurs, popping around to satisfy their curiosity. Of course, I’m sure Loveridge’s sentiments would find happy agreement today: “Probably only a zoologist can look at an uncaught cobra and feel the joy a child feels on Christmas morning.”

The paper’s worth reading for the various stories about the “Demon Curator,” including the drawer labelled “string too short to use” and the famous footnote in the 1957 Loveridge and Williams turtle monograph.


Male and Female Anoles that Look Different: Anolis transversalis

transversalis doc frog

Anolis transversalis, female on the left

We’ve talked previously about anole species that differ in the color of their dewlaps, but I don’t recall any discussion of species in which the males differ markedly in body patterning. Certainly, that happens a lot. For example, we’ve talked a lot about polymorphisms in female back patterns, but in most of these species, the males don’t have any of the patterns shown by the females. And in this case, and many others, one sex is patterned and the other one pretty much isn’t.

In any case, Anolis transversalis is a great example of a species in which both sexes are patterned, but differently. And to boot, their dewlaps are differently colored as well. What a species!

Does anyone want to suggest–or better yet, supply photos–of other species in which both sexes are patterned, but differently?

Oceanic Dispersal by Tortoises and Iguanas


tortoise routeRecently, a 2006 paper on giant land tortoise dispersal has been going around social media. The story is that a tortoise from Aldabra, a tiny speck of an island north of Madagascar, washed ashore in Tanzania, some 700+ kilometers away. Barnacles encrusted on the tortoise’s legs suggest that the chelonian had been adrift for 6-7 weeks, an estimate that makes sense given the prevailing currents. The article summarizes several other, not-quite-so-well documented, cases of tortoise dispersal. These stories make clear that tortoises can disperse over long distances of open ocean. Thus, it is not surprising that they occupy far-flung islands around the world (and remember that until the onslaught of humans, they used to occupy many more islands, such as Madagascar, Mauritius, and New Caledonia).

This is all well and good, but why discuss it in Anole Annals? After all, our little four-legged friends weigh a few grams, not many kilograms, and they don’t carry a flotation device on their back. Does the dispersal ability of these behemoths tell us anything about how anoles reached their island homes?

Let’s go to an example closer to home, from a paper in 1998 published by Ellen Censky in Nature. In that paper, Censky et al. reported an observation from 1995 of a large mat of vegetation washing ashore on the Caribbean island of Anguilla (described as “a mat of logs and uprooted trees, some of which were more than 30 feet long and had large root masses. Local fishermen say the mat was extensive and took two days to pile up on shore.”). This in itself was not so unusual—such mats wash ashore regularly, especially in hurricane season. What was unusual is that riding this vegetation was a passel of green iguanas, a species native to some islands in the Caribbean, but not Anguilla. As onlookers watched, the vegetation washed ashore and, like tourists disembarking from a cruise ship, the 15 iguanas stepped off onto the beach. And like the occasional tourist, the iguanas liked it so much that they never left. Rather, they settled, put down roots, and raised a family. As far as I know, the iguanas are still there to this day.

censkyBut where did they come from? One bit of information did not make it into the article, but Ellen Censky has kindly allowed me to report it here. There was a clue in the mat of vegetation, in the form of a street sign. In French! That narrowed the possibilities considerably, and a bit of sleuthing established that the street sign, and hence the saurians, came from the island of Guadeloupe, where iguanas are native, and where Hurricanes Luis and Marilyn had struck some weeks before. Hurricanes often knock enormous amounts of vegetation into the water, explaining the formation of the vegetation mat.

True, iguanas are bigger than anoles, but otherwise this is exactly the mode of transport hypothesized for anoles. For example, large amounts of vegetation often fall into the Amazon and Orinoco Rivers in South America and end up floating far out to sea, as chronicled by Blair Hedges in a paper a while back. It’s not that hard to imagine a female, with eggs or storing sperm, hunkered down in such vegetation and managing to survive such a journey. It probably doesn’t happen often, but as Ernest Williams pointed out in an overlooked paper on colonization years ago, given millions of years, the unlikely becomes probable. Phylogenetic evidence indicates that the Caribbean anole radiations are the result of two colonization events from the mainland. In addition, it suggests that the Norops radiation on the mainland is a result of back-colonization from the islands—over the 40 million plus year history of anoles, that doesn’t seem very unlikely.

Island Gigantism in a Mexican Anole

Anolis nebulosus

In a recent paper in the Italian Journal of Zoology, Senczuk and colleagues report an interesting finding on the clouded anole, Anolis nebulosus. On the mainland, the species is fairly petite, with males averaging 40 mm SVL. However, on a very small, offshore islet, only half a kilometer from the mainland, males grow to an average of 53 mm, and the average female is larger than the largest male on the mainland.

What is responsible for such great disparity in size? Two prime possibilities are that most of the anoles predators are absent from this small island and that the island has a seabird colony, which may lead to greater quantities of insect prey.

In a fascinating previous study, some of the authors of this paper documented many other interesting differences between the mainland and island populations, such as the fact that lizards in the island population are much more active and display more. Clearly, this is a situation worthy of further study.


The clouded anole Anolis nebulosus (Squamata: Polychrotidae) is widespread on the Pacific coast of Mexico. The species also inhabits Don Panchito, a small islet located near the coast of the Chamela-Cuixmala Biosphere Reserve in the state of Jalisco. We studied the extent of intraspecific differences in morphology (absolute size and body proportions) and in mtDNA sequences (16S and NDH2) between the population living on the islet (N = 18 for morphometry; N = 12 for mtDNA) and the one on the facing mainland (N = 38 for morphometry; N = 16 for mtDNA). The individuals on the islet are larger than those on the mainland with little overlap in size for either males (islet: 52.79 ± 1.82 mm; mainland: 40.96 ± 2.99 mm) or females (islet: 46.18 ± 3.24 mm; mainland 37.14 ± 2.13 mm). The presence of insular gigantism, as here found in A. nebulosus, seems uncommon in the genus and could be explained as a combination of low predation pressure and higher intraspecific competition on the island. Moreover, we found that sexual dimorphism (SD) is higher in the island population than in the mainland one. The molecular analysis shows the absence of shared haplotypes between the island and mainland populations. Ten mtDNA haplotypes belonged to the mainland population and three to the island population. The shape of the minimum spanning network and of the mismatch distribution indicates a single colonization event. These molecular data indicate a certain degree of isolation of the island population notwithstanding its proximity to the coast. The morphological characteristics of the anoles on Don Panchito match with the expectation of the so-called “reversed island syndrome” theory, which predicts an increased body size and sexual dimorphism in lizards living on very small islands characterized by unpredictable environmental conditions.

Aquatic Anole Displaying

Here at AA, we seem to have an obsession, hopefully healthy, for a few things: knight anoles, anoles and water, and big dewlaps. And here’s a combination of two of them, a mainland aquatic anole displaying its enormous dewlap. Wowwee! It’s big and beautiful. What is it with mainland anoles and their big throat fans? This is a youtube video posted by MrKbosker, identified as A. aquaticus.

And not to be outdone, InBio, the Costa Rican biodiversity institute, brings us this mellifluous footage of A. polylepis strutting its stuff.

The Anoles of La Cumbre, Colombia

ventrimaculatus DSC_0021x

Anolis ventrimaculatus. Photo by Jonathan Losos.

We (Rosario Castaneda, Anthony Herrel, Luke Mahler and I) have just completed the first leg of our 2.5 week Colombian anole sojourn. First up: La Cumbre in the hills north of Cali. At  2000 meters, it was chilly! Going out our first night, we found plenty of long-legged Anolis ventrimaculatus. Imagine our surprise the next day when they were hard to find when active! This was reminiscent to us of A. gemmosus in Mindo, which also is very abundant at night–we’re talking Caribbean anole night abundance–but not easy to find while active.

The ones we did find were generally low to the ground, often on tree trunks, sometimes on vegetation. They refused to move when we filmed them, but their stomach contents indicated that they had been foraging, even at temperatures in the upper teens. These are tough, wily buggers!

We found two other species in smaller numbers, but only at night. The most exciting was A. calimae, which was not known from the locality at which we were working. We found a male and a female. They look moderately like twig anoles–elongate, slender body habitus–but there limbs are on the long side. We’ll see what the morphometrics say. However, when we released them, they behaved exactly like twig anoles, squirreling to the far side of a branch, creeping forward, carefully placing one foot, then the next, freezing. Unfortunately, despite intensive efforts, none were located during the day, perhaps not surprising, as many twig anoles are very cryptic and hard to find, particularly given that they live in dense vegetation.

Female Anolis calimae. Photo by Jonathan Losos.

Female Anolis calimae. Photo by Jonathan Losos.

Lastly, we found a number of A. mariarum in dense fields of high, stout grass. The photo below shows one such area. These lizards have to be living in the grass; they’re too far from anything else (the occasional tree notwithstanding. Yet search as we might, we couldn’t find them during the day. Our guess is that they are active in the spaces on the ground beneath the grass. In fact, when we let the lizards go, they seemed quiet happy to scamper about, and even display at each other, under the grass canopy.


Anolis mariarum’s field of dreams, where several were found sleeping, but none could be found during the day.

An exciting, if chilly start, but we’ll soon be thinking wistfully of cool days and evenings as we head to our hot and steamy next location.