Tag Archives: behavior

Female Brown Anole Inspecting Nest Pot

It is not new to most of us that female lizards choose between different nest sites (e.g. Shine & Harlow, 1996; Warner & Andrews, 2002), anoles included (Socci et al., 2005; Reedy et al., 2012 – covered on Anole Annals). But what is new to me is how females assess soil characteristics to decide where to lay their eggs.

Brown anoles in an intimate moment.

Brown anoles in an intimate moment.

For context, I recently started to breed brown anoles in the lab for the first time. I’m using large vertical screen cages in an outdoor set up, which I believe makes them pretty comfortable to keep their daily anole life. There have been lots of  male-male interactions (displaying and serious fights), mating and nesting.

A few days ago I started to notice females head down in the nests pots, breathing heavily from time to time. I wondered if they were inspecting the nest pots before laying and shared a video on Twitter. They take a long time in that position, which made me really curious to know how they assess their chosen nest-site characteristics. Let me know if you know more about it. Posted above is the video I uploaded to youtube.

I feel so lucky to be able to observe all these cool behaviors and I hope to share some more soon!

JMIH 2016: Escaping in the City

2016-07-10 09.00.19

Kevin Aviles-Rodriguez, from the Revell lab at U. Mass. Boston, gave the second urban anole-themed talk of the meeting. Kevin presented his Master’s thesis work that he conducted with the Kolbe lab at U. Rhode Island in a talk titled, “Structural habitat alterations caused by urbanization influence escape behavior of a common lizard.”

Urban habitats are drastically modified and present novel resources and threats for animals that persist and utilize these spaces. Structurally, urban habitats have different types of surfaces that are smoother, broader in diameter, and often more vertically oriented (90° angle). Urban habitats also present abundant and novel food resources in terms of human food and insects attracted to lights and garbage. But with the abundance of food and novel niche space also comes an abundance of novel predators such as cats and dogs kept as pets.

Kevin wanted to know how Anolis cristatellus from San Juan, Puerto Rico and South Miami behaved in urban habitats compared to forest habitats when perceiving a predation threat. Although there are obvious costs of not escaping a predator successfully, there are also costs of fleeing when not necessary in terms of lost feeding opportunities and disrupted social interactions (mating, territory defense). Kevin wanted to know if the urban environment influenced escape behavior decisions. Specifically, he had two objectives: (1) To quantify escape behavior (squirreling, jumping, or sprinting) and how this relates to different types of perches found in urban areas. (2) To measure flight-initiation distance (FID), or how close one can approach an animal before it flees, to see if there are differences between forest lizards and urban lizards.

2016-07-10 09.07.18Kevin found that as perch diameter increases, the probability that a lizard will squirrel around a perch or sprint up the perch increased and the probability of jumping decreased. Interestingly, when he also looked at perch use, he found that the majority of lizards were using perches of thinner diameter where the probability of jumping was highest. Urban lizards also tended to use more isolated perches, which he defined as the number of nearby potential perches within 1 meter. When nearby perch density was lower, lizards tended to jump less – perhaps not all that surprising since they have fewer places to jump to. Kevin also found that escape strategy differed based on the type of perch used. In urban habitats, on trees and on metal posts lizards squirreled more frequently than they did in forest habitats. Interestingly, on cement walls (e.g. buildings) lizards did not jump at all and mainly sprinted to escape. 2016-07-10 09.10.05Kevin offered a few possible explanations for this trend. For one, building perches tend to be more isolated than trees and so it may simply be that lizards on these substrates have nowhere to jump to. A second possibility is that the lizards have trouble jumping from these perches since they are more vertical than the optimal angle for jumping (39-42°, Toro et al. 2003).

In his final analysis, Kevin found that flight initiation distance (how close you can get to the animal before it flees) was very short for animals perched on urban trees and metal posts. In fact, he commented that on some occasions he was able to get close enough to touch the lizard before it fled! This difference was significantly shorter than for animals perched on trees in the forest and for animals perched on painted concrete walls in the city.

To Eat or Be Eaten: How an Anole Decides When to Forage

Anolis cristatellus in survey posture (photo by K. Winchell)

Anolis cristatellus in survey posture (photo by K. Winchell)

Foraging decisions are the result of a complex decision-making process involving intrinsic factors (physiology, body condition, cognitive ability, sex, ontogeny, etc.) and environmental factors (food availability, structural habitat, presence of predators and competitors). In short, it comes down to the tradeoff between the benefits of energetic gain and the potential costs of predation risk, missed opportunities for reproduction, and expended energy. However, little is known about the specifics of this process – what information are lizards considering when making this decision? By conducting manipulative field experiments on Anolis cristatellus in Puerto Rico, Drakeley et al. (2015) attempt to elucidate what environmental factors influence the decision to forage.

The authors conducted field experiments involving feeding trays in the wild. The Puerto Rican crested anole is a trunk-ground anole and a sit-and-wait forager. When receptive to feeding, it perches head down in “survey posture,” a behavior it reduces when satiated. Aside from movement associated with foraging and social interactions, this species typically remains stationary on a perch. Because of this, the authors were able to easily locate a focal individual and count the number of conspecifics present, using natural variation instead of manipulating the number of animals present.

In the first experiment, they manipulated the food quantity to determine how foraging decisions differ when food is plentiful versus scarce and how this is influenced by the presence of competitors. They found that lizards foraged faster when there were more conspecifics present and food was scarce. When no lizards were near the feeding tray and the feeding tray was full, the focal animal took longer to approach the tray to take the mealworms compared to when there were many conspecifics nearby. Interestingly, this was not related to overall local density, but rather to the number of conspecifics in the immediate vicinity. Therefore the decision to forage likely involves an instantaneous assessment of the local conditions rather than knowledge of the long-term population trends. The authors also considered several other factors and found that although body size was related to foraging latency (larger lizards were quicker to the feeding tray), no other environmental factors were relevant (temperature, humidity, perch height, perch diameter, local density of conspecifics).

Figure 1 from Drakeley et al. (2015). Latency to feed was correlated with the number of conspecifics present and abundance of food.

Figure 1 from Drakeley et al. (2015). Latency to feed was correlated with the number of conspecifics present and abundance of food.

In the second experiment, the authors chose focal animals farther from the feeding trays and considered distance as a proxy for predation risk. The farther the lizard was from the tray, presumably the greater exposure it had to predators as it moved towards the tray. They found that under this scenario, when risk was elevated, there was more latency in the approach of the food tray. This effect was driven mainly by the increased use of intermediate perches rather than a direct approach across open ground. Increased latency to feed was observed regardless of how abundant the food was or how many conspecifics approached the tray, supporting the conclusion that this effect was because of the perception of greater predation risk (i.e. movement over a longer distance). They also found that larger lizards had a lower latency to feed (approached the feeding tray more rapidly) and lizards not in the foraging position had a longer latency to feed.

In summary, it seems that anole foraging decisions are quite complex. Lizards appear to weigh the risk of predation taking cues from conspecific behavior and abundance versus the abundance of food to make instantaneous decisions to approach a novel feeding source.


 

Drakeley M, Lapiedra O, Kolbe JJ (2015) Predation Risk Perception, Food Density and Conspecific Cues Shape Foraging Decisions in a Tropical Lizard. PLoS ONE 10(9): e0138016. doi:10.1371/journal.pone.0138016

Anolis huilae en Cacería (Anolis huilae Hunting)

Macho de Anolis huilae acechando su presa.

Macho de Anolis huilae acechando una presa.

Observaciones realizadas en mi finca (Ibagué – Colombia) de un macho de Anolis huilae acechando su presa y una hembra predando su presa. He tenido la oportunidad de observar individuos de ésta especie cazando orugas, larvas y moscas y, la manera como ellos invierten algún tiempo para acechar a sus presas para capturarlas . Aún se desconoce la dieta exacta de esta especie de lagarto endémico de la cordillera Central de Colombia.

Predación por parte de Anolis huilae

Predación por parte de una hembra de Anolis huilae

Editor’s note: Google translates the passage above as follows. It’s amazing how good this programs are getting!:

Observations made on my farm (Ibague - Colombia) of a male Anolis huilae stalking his prey and a female predating its prey. I have had the opportunity to observe individuals of this species hunting caterpillars, larvae and flies and how they spend some time to stalk their prey to catch them. The exact diet of this species of lizard endemic to Central Cordillera of Colombia is still unknown.

Holiday Observations Of Anolis Maynardi

Our A. maynardi in Little Cayman seem to be thriving. They have learned when I water the garden & have taken to either dropping out of the trees to lick waterdrops from the bushes or positioning themselves in advance. We also often see maynardi climbing up the outside of the window screen & licking the metal or licking the A/C unit..

Does the window screen taste salty too?

Licking the airconditioner, for salt? A wet-finger test showed that the surface was slightly salty. Photo by George Chaplin.

Waiting for water in the morning.

Anolis scriptus 4

Anolis scriptus- An Archipelagic Anole

Though they are not as flashy as some of their West Indian relatives, Anolis scriptus, the Southern Bahamas Anole, is an ecologically important and interesting component of the herpetofauna of the distal end of the Bahamas Archipelago. Small and brown to brownish green, they seem to be rarely photographed or discussed, so I thought they deserved a post on Anole Annals. These are individuals from the Turks and Caicos Islands- where they are ubiquitous on most emergent land- from the largest islands at over 290 square km to the smallest rocks with some vegetation. Interestingly, this species has been shown to modify its perch height in response to the presence of predators (more on predation in a later post). When curly-tailed lizards (Leiocephalus psammodromus) are around, the anoles are more arboreal (Smith 1994;1995). However, we have found this to be the case mostly on smaller islands, while on larger islands the anoles will still use the ground and lower tree trunks, even in close proximity to high densities of curly-tailed lizards.

Thermal Ecology of Anolis cristatellus

The recent literature has been full of doom and gloom regarding the prospects for lizard survival in the face of global climate change (e.g., Sinervo et al. 2010).  A talk by Alex Gunderson from Manuel Leal’s lab at Duke University provided some important new insights on how our favorite lizards are likely to weather this storm.  Gunderson investigated thermal ecology of Anolis cristatellus at nine localities, including four mesic and five xeric locales.  His data included thousands of field collected temperature records from live animals and copper models as well as data on preferred body temperature and sprint speed performance across a range of temperatures.  Temperature data from live animals and co-distributed copper models showed that the xeric, but not the mesic, populations are behavioral thermoregulators that tend to be found in cooler spots than the randomly placed copper models.  Even with the benefit of behavioral thermoregulation, the xeric forest lizards were consistently active at temperatures that exceeded their preferred body temperature.  When Gunderson integrated these findings with data on sprint speed performance and climate change, he found that the xeric forest animals are likely to suffer significant reductions in performance associated with climate change.  Gunderson ended with a teaser by showing that he has accumulated comparable data on performance across a range of temperatures for all the other Puerto Rican anoles.  Next year’s talk should be a blockbuster!

A Primer on Filming Anole Behavior – Part 1

A field assistant, Sarah, films anole behavior in semi-natural enclosures

I’m in the midst of my fourth summer of field work, and over the course of this time, I have spent many hours filming male Anolis carolinensis. I’ve done this work under several conditions; one project involved filming known animals in the field, a second required filming staged encounters between males in the lab, and the final (and current) project has me filming animals in semi-natural enclosures. These experiences prompted me to create this post, which I hope will be useful to anole researchers and enthusiasts who are embarking on projects that involve capturing video of lizards doing the things that fascinate us. Today, I’ll begin with a discussion of cameras and in a later post, I will write about other equipment as well as some of the techniques I’ve employed to capture useful images.

The Camera

The most important piece of equipment. Continue reading A Primer on Filming Anole Behavior — Part 1

Anoles Respond to Robotic Lizards

Photo from Partan et al. (2011)

For about a decade now, several researchers have used remarkably realistic looking robotic lizards to study lizard behavior. A pioneer in this approach—especially with regard to studying anoles—is Terry Ord, now at the University of New South Wales. You can see videos of his robotic lizards, as well as clips of a variety of anole species displaying, on the Terry Ord Channel on YouTube (or read about his most recent work here). As you’ll see, these robots are very realistic, both in terms of appearance and motion pattern—they bob, pushup, and extend their dewlap just like a real anole. In fact, even when the rubber body of the lizard hasn’t been attached, the underlying struts move in a clearly anole-like fashion. Bottom line, at a distance, I think most humans would be fooled by a displaying robo-anole. And lizards seem to be fooled, too, because they clearly respond by displaying and approaching the robot—check out the videos and/or Ord’s papers. Or read the recent paper by Partan et al., which demonstrates that A. sagrei responds more to a robot giving the typical signature display than to one presening a different display occasionally given by a lizard in the population.

Just like audio playbacks which revolutionized the study of bird vocal communication, robotic lizards provide the opportunity to rigorously examine lizard behavior in a controlled and replicated manner. Many different questions could be examined, but one of particular interest concerns how anoles distinguish conspecifics from heterospecifics. By altering the display pattern—the timing and amplitude of headbobs, pushups, and dewlap extensions—and by altering the color and pattern of the dewlap, researchers have the ability to understand species-recognition. In turn, such an understanding may provide critical insight into how new species arise, because speciation is the result of changes that lead individuals to no longer recognize each other as conspecifics.