After scampering about much of North America the past few decades, I once again live in my hometown of Ormond Beach, Florida — on the northern edge of Volusia county. When I was a kid, back in the late 70s and early 80s, I spent much of my time tangling with and studying our local anoles. The Carolina greens (A. carolinensis) were dominant back then, covering our walls, windows, trees, and (sometimes by forced measure) our ear lobes. Every now and then I’d find a Cuban brown (A. sagrei) — usually around the shopping centers and strip malls. Nowadays, of course, that coin has flipped. The Carolina greens have moved back up into the higher foliage and the Cuban browns dominate our shrubs, walls, and windows.
I remember actually finding a Cuban brown anole on our property in 1984 or so. I was in 4th grade, drunk on Star Wars and lizards. I managed to catch the little non-native lizard and put it in my anole terrarium (a homemade wood-and-open-screen enclosure my dad and I built). I was in the habit of catching anoles (and the occasional snake), keeping and watching them for a day or two, and then releasing them back into the yard. Needless to say, the Carolina green already in the enclosure wasn’t too thrilled with his new roommate. Though guilt eventually kicked in the following day, I admit I was somewhat delighted by the defensive/discomfort color play of that poor Carolina green. Usually, they’d be cool, smooth emerald green with very little patterning… but distressed or riled up Carolina greens certainly know how to put on a good color and pattern show.
Soon enough, I released the Carolina green back into the yard and kept the Cuban brown for another day or two. This little moment of tension, however, leads me to the point of this post: the distress patterns of our local Carolina green anoles. More specifically, I’m interested in the presence of a supraspacular dark spot that shows up with some individuals. It’s a dark spot with light trim that sometimes appears just above and behind the front shoulder line — as seen in this particularly ornate individual photographed in Miami-Dade county on 18 March 2017:
Miami-Dade county, Florida; 18 March 2017
Miami-Dade county, Florida; 18 March 2017
Miami-Dade county, Florida; 18 March 2017
This Miami-Dade individual really stuck out to me. It’s patterning was distinct. It was quite large. It had that supraspacular spot. Most notably, it was still wielding quite a bit of green. Could this be A. porcatus? Like many naturalist-lizard enthusiasts, I tend to catch myself up in the eternal cycle of porcatus-or-not? when I’m in south Florida. Heh. Nowadays, my assumptions generally fall on the side of A. carolinensis unless I’m with somebody more in-the-know who can tell me differently with confidence; this hasn’t happened yet. Honestly, I have a hard time seeing a clear difference between the two. I’m glad I’m not alone.
Though distinct, this fabulously mottled Green wasn’t the only Green I’ve photographed with that supraspacular spot. Here’s an impressive male tangling with a Cuban brown anole in the Lower Keys of Monroe county, Florida, on 08 June 2007:
Monroe county, Florida; 08 June 2007
Monroe county, Florida; 08 June 2007
Further north, in my home territory, I’ve only noticed and photographed two individuals with that spot, albeit with less figure-ground contrast between the spot and the trim.
Orange county, Florida (05 September 2011):
Alachua county, Florida (05 December 2011):
Both were in WTF-dark-mode (as I call it).
Of note, I spent a few years in Valdosta, Georgia, intensely watching anoles.
Figure 1. Knight anoles (Anolis equestris) are large, arboreal, and highly frugivorous lizards native to Cuba and introduced to Miami, Florida in the mid-20th century. This adult female was found perched on the trunk of a strangler fig (Ficus aurea) in Miami, Florida, a common sight in south Florida. Strong jaws and a large gape enable knight anoles to consume a range of large food items including snails, locusts, small vertebrates (occasionally), and some moderate-sized fruit. Photo by S. Giery.
I remember the first knight anole (Anolis equestris) I ever caught. Details about how I caught it are gone, but I certainly remember the resulting bloody thumb. I was impressed and intrigued by the force and stamina of its bite – I needed to study this critter (fig. 1). Motivated by the recent publication of a short paper on knight anole diets, below, I break down a few years of research into the trophic ecology of the knight anole into a brief recount of what my collaborators and I have found.
Preliminary observations on knight anole trophic ecology
Following that first encounter I conducted a simple study of anole diet and habitat use around the Florida International University (FIU) campus in North Miami. In general, the findings showed some sensible results: Cuban brown anoles (A. sagrei; trunk-ground) perched low and ate a wide variety of terrestrial insects, Hispaniolan bark anoles (A. distichus; trunk) skittered up and down the trunk and ate – almost exclusively – ants, and Cuban knight anoles (A. equestris; crown-giant) ate larger food items than the other two species and tended to stay in the canopy (Giery et al. 2013). Again, this pattern of diet and habitat use was expected except for one thing – the composition of knight anole diet. Prior to embarking on the study, I had expected, based on their large size, strong bite force, the abundance of smaller anoles, and a few anecdotal accounts, that these powerful lizards would be eating lots of anoles. Surely these were the T-Rex of the trees and their direct interaction with other anoles was a predatory one. Yet in all the knight anoles that I dissected in this first study (n =21), not a single one contained vertebrate remains. Instead, nearly half of the diet (by volume) was fruit, specifically strangler figs (Ficus aurea; look to Supplemental table 1 for summary diet data). Our stable isotope data corroborate these observations – rather than the enriched 15N signature we‘d expect from an anole predator, the isotope data suggested similar trophic levels for brown, bark, and knight anoles. So what gives? Where was the evidence for a swaggering, arboreal meat-a-saurus?
Years later, James Stroud and I assessed the stomach contents of more knight anoles (n = 10) from a different site in Miami (Fairchild Tropical Botanic Gardens. James had directly observed knight anoles eating three different species of anoles there (1,2,3,4) and so we thought another look at their diet would be interesting. Once again, the majority of gut contents consisted of fruit, this time from royal palm trees (Roystonea regia). In fact the only evidence for vertebrate prey in this population was a 1 cm section of green anole tail. These data supported earlier observations (Brach 1976; Dalrymple 1980, Giery et al. 2013) demonstrating that fruit is a major component of knight anole diet, and vertebrates aren’t. It seemed that the canopy superpredator role I’d imagined for knight anoles was increasingly less likely. In fact, in all three previous examinations of knight anole diet, few instances of vertebrate predation by knight anoles are observed (table 1). The evidence spoke, knight anoles were sharp-toothed, veggie-sauruses with a deliberate, powerful bite.
An opportunity presents itself
Understanding the trophic ecology of anoles has been an ongoing project of mine for some time, the paper that we’ve just published in Food Webs (Giery et al. 2017) would not have come without the serendipitous post-capture … deposition … of a few seeds. An adult male passed two royal palm seeds which were planted post-haste in the greenhouse at FIU. It took a few months but the seeds eventually geminated, demonstrating that seeds consumed by knight anoles are viable and suggesting a role as seed dispersers (fig 2).
Figure 2. Adult knight anoles (Anolis equestris) often inhabit the crowns of royal palms (Roystonea regia) in Florida and Cuba. Note the numerous ripe fruits above this displaying male photographed at our study site in Coral Gables, Florida (A). Roystonea regia seedlings resulting from seeds passed naturally by a wild-caught A. equestris. Both seeds were planted at the same time, but germinated nearly 130 days apart (B). Adult royal palms can reach 30m high and are an ecologically and economically important plant throughout their range (C). Photos by J. Stroud (A & B) and S. Zona (C).
We felt that these data filled an important gap in our understanding of how anoles interact with other species. Certainly, the literature (e.g., Herrel et al. 2004; Losos 2009) and our data from Florida (Giery et al. 2013, 2017), Bermuda (Stroud, unpublished), and The Bahamas (Giery, unpublished) show that frugivory is widespread and sometimes quite common in anoles. Yet, the fact that seeds remain viable after passing through the guts of anoles presents a new facet to their interactions with plants. For more about what we know about lizard-plant interactions go ahead and check out the references in our paper (there’s good stuff from Europe, and recently, the Galapagos).
Whether the interaction we illustrate in our paper is ecologically important (i.e., increasing germination rates via ingestion and/or dispersal) requires substantially more study. Yet, the relationship between knight anoles and royal palms has been noted for nearly a century in Cuba suggesting their interaction is more widespread than just Florida. For example, Barbour and Ramsden (1919) remarked on the frequent coexistence of royal palm and knight anoles in Cuba. Interestingly, these early works often focused on the potential consumption of vertebrate prey, despite reports from Cubans that knight anoles often ate fruit – a bias matching my own preconceptions about the nature of this great anole:
“As to the food of the great Anolis [equestris] we know but little; it is surely insectivorous and Gündlach records that he once heard the shrill scream of a tree frog Hyla and found that it had been caught by one of these lizards. The country people all declare that they feed largely upon fruit, especially the mango; it is not improbable that this idea arises from the fact that they are frequently found in mango trees. We have always imagined that this circumstance was due in part at least to the excellent cover offered by the splendid growth of rich green foliage of the Cuban mango trees; it, however, has been seen eating berries (Ramsden). With good luck one may occasionally see two males of this fine species chasing one another about, making short rushes and charges at each other, accompanied by much tossing of heads and display of brilliant dewlaps When this mimic battle takes place about the smooth green top of the trunk of a stately Royal Palm, it is a sight not easily forgotten.” from Barbour and Ramsden 1919.
Anyways, we hope our short paper does two things. First, we hope that our summary of knight anole diet in Florida accurately illustrates their trophic ecology. Second, seed dispersal of native trees (royal palm and strangler fig) by an introduced vertebrate represents an interesting contrast to the negative effects usually attributed to introduced species (e.g., brown anole). We hope our observations highlight the diverse relationships between anoles and plants in the Caribbean region. Finally, we realize that our data are merely suggestive and effective seed dispersal by anoles has yet to be demonstrated. Nevertheless, we’re excited by the potential for new research directions stimulated by our observations.
At the time, I asked if anyone had a photo of the blue-eyed Anolis etheridgei. Photographer par excellence Rick Stanley quick obliged, but I never got around to posting his photo, so here it is.
But the bigger question is: what about those blue eyes? Why hasn’t anyone studied the phenomenon? If you’ve got a good photo of a blue-eyed anole, send it here!
Many primarily insectivorous lizards will eat other vertebrates on occasion, a behavior that has been reported in many species of Anolis. One unifying generality is that such carnivory is size structured, with the predator usually being substantially larger than the prey (Gerber 1999. In Losos and Leal [eds.], Anolis Newsletter V, pp. 28–39. Washington University, Saint Louis, Missouri). Not surprisingly, reports of anole carnivory pertain primarily to middle-sized and larger anoles. Here we report carnivory by a small anole of the species A. pulchellus. To our knowledge, this is the first instance of carnivory reported for this species and one of few for any similar-sized anole (the record noted by Henderson and Powell 2009. Natural History of West Indian Reptiles and Amphibians. University Press of Florida, Gainesville, Florida. 495 pp. is based on the observations reported here).
Fig. 1. Female Anolis pulchellus in the process of ingesting a Sphaerodactylus macrolepis.
We observed a female A. pulchellus (SVL ca. 38 mm) capture and consume a Sphaerodactylus macrolepis (SVL ca.18 mm) in the leaf litter at approximately 1430 h on 25 September 2006, on Guana Island, British Virgin Islands, near the head of the Liao Wei Ping Trail at roughly 18.47916°N, 64.57444°W (WGS 84). The anole jumped from a low perch (ca. 20 cm above the ground) to the ground and bit the gecko, which escaped and fled 15–20 cm to the opening of an ant nest. The anole attacked the gecko again, seized it in its mouth and carried it approximately 10 cm up a vine, a distance of 15–20 cm from the site of attack. Initially, the anole held the gecko upside down (i.e., dorsal surface facing down), biting it between the fore and hind limbs on the left side. Eventually the anole worked its grasp posterior to the base of the tail, still on the left side. At this point, parts of both the base of the tail and the left hind limb were in the anole’s mouth (Fig. 1). The anole then manipulated the gecko so that it was no longer upside down, but rotated about its long axis by roughly 90 degrees (the ventral surface of the gecko was then oriented forward relative to the anole) at which point it was biting the gecko at the base of the tail and possibly by the left hind limb; the anole eventually manipulated the gecko so that it held it tail-first in its mouth, dorsal side up, at which point the anole proceeded to ingest the gecko tail first (during this time, the tail itself broke off and was carried away by ants, which had been biting the gecko in several places since shortly after it was
captured by the anole). Total time from capture to complete ingestion was approximately five minutes.
Predation on Sphaerodactylus geckos has been reported in anoles of only a few species, none of which are as small as Anolis pulchellus (Henderson and Powell 2009. Natural History of West Indian Reptiles and Amphibians. University Press of Florida, Gainesville, Florida. 495 pp.). However, given the size discrepancy between the lizards in these two clades and their extensive coexistence across the Caribbean, we suspect that such interactions may occur with some frequency. Moreover, the high population densities of some Sphaerodactylus geckos (e.g., Rodda et al. 2001. J. Trop. Ecol. 17:331–338) and the diurnal activity of several species (Allen and Powell 2014. Herpetol. Conserv. Biol. 9:590–600) suggest that they may be important prey items for anoles.
Photos and notes from Bianka Sanó, a Dominican biology student interested in herpetology:
On the morning of December 26 2016, at 0940 h, in Haina, San Cristóbal, two males of the genus Anolis, belonging to different ecomorphs, A. distichus (trunk), and A. chlorocyanus (trunk-crown), were observed engaged in combat. The lizards were found on a concrete substrate both biting each other on the dorsum (A. distichus held its bite closer to the forelimbs), and remained motionless for approximately 30 seconds. In spite of the A. chlorocyanus being of a larger size, his opponent seemed to be taking the lead in the confrontation; subsequently the A. chlorocyanus got off the engagement and in its attempt to escape, the A. distichus attacked again by biting the A. chlorocyanus in the same place, but this time the A. chlorocyanus failed to reach its opponent in order to defend itself. After about 20 minutes the A. distichus released his opponent and the two went in opposite directions, and while in the move, it was noticeable that both animals were injured.
This video was filmed and shared by Jen Moss of the Welch Lab at Mississippi State University. She observed the encounter near Preston Bay, Little Cayman, and it’s a great video showing this behavior. Lots of dewlaps, pushups, and potential exposure to predators owing to the use of a non-natural substrate. Thanks Jen!
Anolis smaragdinus (left) and Anolis sagrei (right) from Long Island, Bahamas. The individual on the right is marked as part of selection study.
This past August, two field assistants and I went to Long Island, Bahamas to collect data on sympatric populations of Anolis sagrei and Anolis smaragdinus as part of a natural selection study. Our primary study area is a small island (approximately 1000 ft x 200 ft) in the middle of a lake with relatively high densities of both species. While in the field we observed some interesting behaviors that I want to share with the AA community in hopes that you will find them interesting as well!
1) Frugivory by anoles was common at our study site, which had an abundant supply of small berries from black torch (Ertihalis fruticosa) and small-leaved blolly (Guapira discolor). Anolis smaragdinus was usually the culprit, although we did we did see one adult male A. sagrei eating fruit.
2) We captured (and released) over 150 unique A. smaragdinus and later re-spotted several of those individuals. During a typical eight-hour day, we encountered 15-20 individuals, a surprisingly large portion of which were a male and a female in the same tree. These instances made a particularly strong impression on me when they were separated by long periods of not seeing any A. smaragdinus. I can think of multiple occasions in which we found a couple together, saw no individuals for another three hours, and then suddenly came across another couple. In several instances, there were three individuals in the same tree. I’m not aware of green anoles mate guarding, and unfortunately the data I have don’t have the resolution to provide much insight here, but the pattern was definitely striking.
3) We observed an act of cannibalism in A.smaragdinus, a species for which cannibalism has not previously been reported (although it has reported for the closely related A. carolinensis). We captured an adult female, saw that she was eating something, and proceeded to lose our marbles after pulling a hatchling (pictured) out of her mouth. Acts of cannibalism by female anoles appear to be rather uncommon (see page 30 of this Anolis newsletter), making this observation perhaps the most intriguing of our adventure!
An adult male San Salvador Bark Anole (Anolis distichus ocior) displaying. Photograph by Guillermo G. Zuniga.
Dayton Antley and colleagues from Avila University, the home of AA stalwart Bob Powell, recently published a detailed study of the ecology of the San Salvador bark anole (Anolis distichus ocior) in IRCF Reptiles & Amphibians (an open-access herpetological journal, with this article available here). Anolis d. ocior is one of 17 recognized subspecies of the diverse distichus group, and is found on only San Salvador and Rum Cay (Henderson and Powell 2009).
Antley et al. assessed microhabitat use, activity patterns, and approach distances of A. d. ocior in an approximately 0.3ha study area on the grounds of the Gerace Research Centre, dominated by Tropical Almonds (Terminalia catappa), Papaya (Carica papaya), and Ficus trees.
A Google Map view of the Gerace Research Centre. The study site (24°07’05.2″N 74°27’50.9″W) is outlined in white.
In assessing patterns of microhabitat use throughout the day, Antley et al. conducted surveys every two hours for two days from 0700h (about 40 min after sunrise) to 1900h (about 40 min before sunset). Size class, perch height and diameter, body orientation relative to the ground, and thermal microsite (sun/shade/mixed) were recorded for every observed lizard. In the following two days, approach distances were assessed. This was achieved by a surveyor, wearing neutrally-coloured clothing, approaching an undisturbed anole at a steady pace and recording the distance at which the lizard reacted. Over two additional days, 10-minute focal animal observations were conducted of individual adult lizards (including both males and females) at a distance of 5m. The number of movements (changes in location or orientation), head turns, and head bobs were recorded for all lizards, with dewlap displays and pushups being additional recorded for males.
Lizards were active throughout the day, with activity peaking in the early morning and before midday. This was compared to ambient air temperatures recorded 1m from the ground in a shaded and sheltered location. This result surprised the authors, as a second activity peak in late afternoon/early evening was expected, as has observed in other similar studies of bark anoles (e.g. Hillbrand et al. 2011).
Mean number of lizards active (bars) and mean ambient temperatures (dots) per time period. Temperature data were collected on two consecutive days.
Adult males experienced highest levels of arboreality during the middle of the day, while subadult males and adult females (grouped together as they can be hard to distinguish from distance) were highly variable (see figure below). Most lizards of all classes were found in the shade, which the authors attributed as evidence for thermal conformity, and facing downward towards the ground, a common trait in many anoles that is most commonly perceived to increase an individual’s ability to monitor potential predators, competitors, or mates. 43% of lizards, however, were observed facing upwards. The author’s note that this behavior is often interpreted as an individual prepared for escape; however as all lizards were observed from distance and undisturbed, they (admirably) explain that this result is difficult to interpret.
A: Mean perch heights (cm) of adult males (L) and subadult males and females (S); B: mean perch heights of adult males at different times of day; C: mean perch heights of subadult males and females at different times of day.
Adult male lizards were bolder than smaller subadult males and females, and retreated at a much closer distance when approached by a surveyor (0.99m +/- 0.07m vs. 1.54m +/- 0.18m). Focal observations revealed no significant differences between adult males vs. subadult males/females in shared behaviors, although there was a high variation in the amount of displaying behavior between adult males. The average time spent conducting dewlap displays was 3%, although one male was recorded investing 47% of his time in a combination of dewlap extensions and pushup displays.
Using all survey data combined, Antley et al. estimate that A. d. ocior in this study plot had a population density of 593 individuals/ha, with lizards observed on all but four of the smallest trees surveyed. Antley et al. note that their density estimate is extremely conservative, and much lower than previously published estimates (e.g. 1.070-5,460 individuals/ha, Schoener and Schoener 1978). The authors suggest that the small size of the study plot may have contributed to the relatively low density.
In all, this is a charming (although admittedly short) study of the natural history of the San Salvador bark anole (A. d. ocior) – a great example of an undergraduate research project that follows through to publication!
References
– Antley, D.L. et al. 2016. Microhabitat, Activity, and Approach Distances of the San Salvador Bark Anole (Anolis distichus ocior). IRCF Reptiles & Amphibians 23(2): 75-81
– Henderson, R.W. and R. Powell. 2009. Natural History of West Indian Reptiles and Amphibians. University of Florida Press, Gainesville, Florida.
– Hillbrand, P.A., A.T. Sloan, and W.K. Hayes. 2011. The terrestrial reptiles of San Salvador Island, Bahamas. Reptiles & Amphibians 18: 154–166.
– Schoener, T.W. and A. Schoener. 1978. Estimating and interpreting body-size growth in some Anolis lizards. Copeia 1978: 390–405.
Anolis chlorocyanus after gliding back to the tower. Photo by Brian D. Farrell
Every summer, a group of students heads down to the Dominican Republic to take the Harvard summer course on biodiversity of the country. As a teaching assistant, I often watch unsuccessful attempts of students trying to catch the abundant fast-moving lizards. Sometimes I also participate, usually resulting in the same outcome. Last week, we were climbing an observation tower in Punta Cana to spot Ridgway’s hawks (Buteo ridgwayi) when Ryan Friedman, a student taking the course, noticed a Hispaniolan green anole (Anolis chlorocyanus) perched on the side of the tower. We thought we would finally outsmart an anole and catch it with our hands. However, the lizard apparently preferred to jump to certain death rather than being handled by us. We watched it falling down about 10 meters, but, instead of going straight down and hitting the ground, it followed a curved trajectory that safely brought it back to the tower (and enabled Brian Farrell, the course instructor, to take a picture after the fact).
This observation seemed remarkable enough for Jonathan Losos to allow this entomologist to report it here, and also made me very curious. Are some anoles able to direct their fall, or maybe to glide with the wind while they go down? Hopefully someone will have the chance to do a controlled trial and figure it out!
An adult nipping grass in the morning; notice the bluish tinge on the inner side of the thigh and dorsal part of tail.
Here is Saara hardwickii , spiny tailed lizards. I observed these lizards in their natural habitat, in the Thar desert in Indian state of Rajasthan. It’s a medium-sized lizard which dwells in semi-arid to arid landscapes of northern India, Pakistan and some regions beyond. A drab colored lizard with a pug head and a distinct fleshy and spiny tail.
Habitat fragmentation and hunting for its tail is the main reason for its dwindling numbers. Folklore has it that its tail has aphrodisiac powers, so its tail is cut and ‘oil’ extracted from it and consumed for the intended purpose.
Interestingly, like iguanas, these lizards also live in a social structure, a ‘society’ composed of adults as well as young ones. They live in ground burrows or termite mounds. Spiny-tailed lizards are diurnal; their activity starts around early morning sun and when the sun sets, surprisingly not even a single individual can be seen! A considerable ontogenic shift in dietary inclination towards herbivory can be seen. Adults feed on grass or diminutive terrestrial flora, whereas young ones are omnivorous, feeding on arthropods.
This fellow was just out of its home and carefully observing its habitat.
