That Reptile Blog – Reptile, Amphibian and Exotic Pet Care and Information

Click:The Green Anole (Anolis carolinensis carolinensis) in the Wild and Captivity; – Natural History – Part 1 to read the first part of this article.

Introduced Anoles
The green anole is the only anole native to the USA, but eight other species, originating as escaped or released pets, have established breeding populations here. The most common and widespread is the brown anole (A. sagrei), now found throughout Florida and in southern Georgia, Alabama, Louisiana, Texas and Hawaii. In many areas it is now more commonly encountered than the green anole.

The knight anole (A. equestris), bark anole (A. distichus), large-headed anole (A. cybotes), Hispaniolan anole (A. chlorocyanus), Cuban green anole (A. porcatus) and Jamaican giant anole (A. gormani) are limited to the vicinity of Miami and Miami-Dade County at this time.

Ill Fated Pets
Green anoles were sold by the millions at carnivals, circuses and through the mail in the 1960’s and early 70’s. Termed “chameleons” due to their color changing abilities, most were fed “sugar water” and expired in short order.

Color Change – not as obvious as it seems
Color change in the green anole has little to do with the background upon which the animal rests (although the colors it exhibits are usually cryptic). Cool or stressed anoles are brown in color, while warm, resting individuals are pale green and warm, active animals are bright green. Anoles involved in aggressive displays develop a black patch behind the eyes.

Unique Climbing Aids
Green anoles are assisted in climbing by transverse lamellae on the bottoms of the toes and feet. These thin structures are divided by thousands of grooves, and provide excellent traction against tiny irregularities in the surface upon which the lizard is moving. Utilizing the lamellae, anoles can even grip dirt particles lodged on glass, and hence climb window panes and aquarium sides easily.

Cold Tolerance and its Conservation Implications
Research has demonstrated that anoles from south Florida lack the cold tolerance exhibited by those in north Florida, and could not survive the winters there. Information such as this is vital in planning reintroduction and captive breeding programs for animals with large ranges. Inter-breeding animals that originate in widely different parts of their range can have disastrous consequences, despite the fact that they are of the same species.

In one case, ibex (mountain dwelling goats) from several European countries were released in the Pyrenees Mountains, to bolster the local population. The animals reproduced, but the offspring resulting from the crossing of native and non-native ibex were genetically programmed to give birth in mid-winter, and the population eventually became extinct.

An interesting summary of research being conducted on free-living green anoles by students at UT Knoxville is posted at:
http://eeb.bio.utk.edu/echternacht.asp

The green anole has long been a pet trade staple, but these active, attractively-colored little lizards have quite an interesting natural history as well. Today we’ll take a look at how they live and cope with people, and point out some of their special traits. Next week I’ll cover their care in captivity. Classification

Family Iguanidae, Subfamily Polytrotinae.

Note: some authorities have reclassified certain Anolis species as Norops.

At least 370 anole species range throughout southern North America, Central America, South America and the Caribbean. All are fairly small, slender, egg-laying lizards. Males possess a large, colorful throat fan (dewlap) that is used in territorial displays and other forms of communication; depending upon the species, the female’s dewlap is smaller or vestigial.

The foot pads of most are equipped with lamellae (please see below) to assist in climbing. Nearly all are arboreal, with the tails of the “bush anoles” (Genus Polychrus) being prehensile. Several species, however (i.e. Genus Pristidactylus), are largely terrestrial.

Anoles feed mainly upon insects, spiders and other invertebrates. Several species have been observed to lap nectar and sap, and the Puerto Rican anole (A. cristatellus wileyae) sometimes consumes fruit.

The green anole is the only species native to the USA, although a number of others have been introduced here (please see below). The green anole population in southwestern Florida has recently been designated as a distinct subspecies, the pale-throated green anole, A. carolinensis seminolus.

Physical Description

The green anole is slenderly built, possessed of a long tail, and reaches 6 -7.5 inches in length. The color of each individual varies from light and dark brown to pale and bright green (please see below).

Males are larger and stockier than females and have a thicker tail base and a wider, more colorful dewlap (throat fan). The dewlap of the male is pink to pale red in color (white or cream-colored in A. c. seminolus), and is vestigial or absent in females.

Anoles clad in various shades of blue are sometimes available in the pet trade. Arising from a genetic mutation, they are quite striking.

Range

Green anoles are found from southern North Carolina west to eastern Texas and southeastern Oklahoma and south to the Florida Keys. They also live in the Bahamas, Grand Cayman Islands, Anguilla and Cuba. There are disjunct populations in Mexico.

Green anoles have been introduced to Belize, southern Japan and Hawaii, and have established breeding populations in those areas.

Habitat

Woodland edges, pine-palmetto scrub, cypress swamps, open forests, overgrown fields, farms, parks, backyards and gardens; highly arboreal.

Status in the Wild

Green anoles adapt well to some human disturbance and may even be drawn to gardens by high insect populations and the humidity generated by frequent plant-watering. They are, however, declining across parts of their range due to over-collection and to the effects of introduced Anolis species that occupy the same habitats and compete with (the brown anole) or prey upon (the knight anole) them.

Diet

Caterpillars, tree crickets, grasshoppers, flies, beetles, moths, ants, roaches, spiders and other invertebrates; they occasionally lap over-ripe fruit, nectar and sap.

Reproduction

The breeding season extends from April to September, although it is shorter in the northern part of the range. Males are highly territorial and battle interlopers. The male’s courtship display consists of vigorous head-bobbing with continued extensions of the dewlap. The dewlap reflects ultraviolet light and is perceived by the female as brilliantly colored.

Males chase females about and grasp them behind the neck during copulation. The first eggs, 1-2 in number, are laid 2-4 weeks after mating occurs. They may be buried in soil or secreted below leaf litter or even left the surface, along a log or other structure. Eggs are sometimes deposited in substrate that has accumulated among air plants or in tree knot-holes above-ground. Additional clutches of 1-2 eggs are laid throughout the breeding season, to a total of 8-10 eggs per female. The eggs hatch in 30-45 days.

 

The 1,200+ skink species form the largest lizard family, Scincidae, and among them we find quite a number of unusual animals. Yet the prehensile-tailed skink manages to distinguish itself as unique in not one, but many ways.Largely unknown in the pet trade until the late 1980’s, these arboreal skinks became widely available when logging in the Solomon Islands brought their formerly inaccessible treetop homes crashing to the ground, and left the lizards in reach of collectors. I and others noticed right away that they were quite different than anything we had run across previously.

A Highly Social Lizard
The limited field studies suggest, and our captive observations support, that prehensile-tailed skinks live in hierarchal colonies (a reptilian social group is known as a circulus) and exhibit a variety of highly-developed social behaviors. Group members seem to recognize one another by scent, and mark their territories with waxy secretions. Although often found in pairs, up to 10 individuals have been collected from a single tree hollow, but the functioning of these groups is not understood.

A Placenta and a Giant Offspring
Females, which average 24 inches in length, have a true placenta. They produce 1, rarely 2, huge (to 13 inches) offspring after an amazingly long gestation period of 6 – 8 months. Esteemed veterinarian and herpetologist Dr. Kevin Wright has likened this feat to that of a woman giving birth to a 6 year old child!

Complex Parental Care
The young stay close to their mothers for some time and the females become very aggressive towards people and other skinks after giving birth. Although we do not as yet understand the interactions between adults and young, it is quite clear that those reared in isolation exhibit, if you will, “anti-social” behavior (they are noticeably more aggressive than other skinks, to the point of charging people opening the door of their cages).

Coprophagy (eating of feces) is common, and some believe that this provides the young with important intestinal flora. Breeding occurs year round in the wild and captivity. The young begin feeding at about 10 days of age, and reach sexual maturity in 10 months to 1 year.

Much More to Learn
All told, a strange and fascinating beast. Although captive longevities approach 25 years, we have yet to scratch the surface when it come to understanding prehensile-tailed skink social interactions.

The American Association of Zookeepers has posted an informative article on this species’ fascinating social structure at:
http://www.aazk.org/forum/viewtopic.php?pid=1320

Today I would like to offer a look at how I set up a terrarium for animals in my own collection. After decades keeping animals privately and professionally, my techniques have become a fusion of tried and true methods and ideas that I have either worked out or (often!) stumbled across. Of primary importance has been the writings and personal advice of many kind and dedicated people.

Wonderful but Neglected Terrarium Pets
I’ve never quite understood why barking and gray treefrogs have remained largely ignored by herptoculturists. Both are beautifully patterned – the gray frog subtly, the barker often quite brilliantly – and almost always make themselves right at home in captivity. Wild caught adults of either species have hand-fed for me as soon as 1 week after capture, and a gray treefrog that I have now approaches the glass when I enter the room, in a much more “turtle” than “frog-like fashion”. At nearly 3 inches in length (and appearing larger due to its stocky frame), the barker is the USA’s largest native treefrog, exceeded only slightly in size by the introduced Cuban treefrog (Osteopilus septentrionalis).

Setting Up a Battery Jar Terrarium
I currently keep 1 barking and 1 gray treefrog in a battery jar terrarium of about 10 gallon capacity. I favor battery jars for the simple reason that they were always mentioned in the naturalist/pet-keeping books of yesteryear. As a child, I had no idea what a battery jar was, but imagined it to be a fabulously exotic item, the possession of which would confer instant “professional animal-keeper” status upon me.

In reality, battery jars are thick-walled, usually cylindrical glass containers available from biological/laboratory supply houses. Their vertical orientation serves arboreal frogs well, but a 20 gallon “extra-hi” aquarium or larger plastic terrarium is also perfectly suitable.

My battery jar was modified for use as a terrarium by Bob Holland, a friend who was well-known in the 60’s and 70’s for his success in keeping – years ahead of most public collections – poison frogs, banded tree snails, woodland salamanders, mosses, ferns and a host of other delicate organisms.

Bob used aquarium silicone and a piece of glass to create a small pool and to attach a hollow piece of lava rock about ½ way up one side of the terrarium. The lava rock functions as a planter, and the area below as secure shelter…the treefrogs rarely use it, but in earlier times it was favored by a marbled salamander (Ambystoma opacum).

My skillful friend cut a ventilation panel into the terrarium’s glass top, a task I would not attempt. Commercial glass cutters can do this for you if you are as “tool-challenged” as I, after which you can silicone a piece of fine screening in place.

The substrate is Eco earth loose coconut with a bit of sphagnum moss mixed in. A layer of aquarium gravel and activated carbon, situated below the substrate, assists in drainage and ammonia absorption. I use live, locally collected moss on top of the substrate – you’ll need to experiment with the moss species, but many do well with moderate lighting and daily misting. Compressed frog moss works well to fill in dark corners, or as a substrate for the entire tank if you prefer.

Live Plants, Light and Decorations
I chose the live plants for this terrarium based upon their serviceability as frog perches and modest light requirements. The aptly-named cast iron plant (Aspidistra elatior) is nearly indestructible, and is often used as a perching site. The Chinese evergreen (Aglaonema modesta), snake plant (Sansiveria spp., not pictured) and earth star (Cryptanthus spp.) are equally hardy. Earth stars are a favorite of tarantula-keepers, as they get by on very little light (they turn brown at such times, but return to red when moved to a brighter location).

A Reptisun 2.0 florescent bulb provides sufficient light for the plants without exposing the frogs to harmful levels of UVB – most amphibians have UVB “filters” in their skin, and actively avoid the sun.

A Caution Concerning Light
I have noticed corneal opacities in green and gray treefrogs that consistently perch directly below even low-level UVB output bulbs. To be on the safe side, keep track of your frogs’ perching habits. Most tend to choose the same spot day after day, and it is usually an easy matter to fashion a shield (i.e. an artificial plant) between the frog and the bulb.

A few attractively-weathered pieces of driftwood provide additional climbing surfaces. Exo terra terrarium plants are extremely life-like, more so when integrated among living plants. I find them especially useful in creating exhibits in zoos and museums, where the plant species used must match those found in the subject animal’s habitat, or where light levels limit the use of live plants.

Heat
One drawback of a battery jar terrarium is the relatively small area that can be vented. In the summer, temperatures within may become too warm for most amphibians, if even a florescent light is used. The aforementioned plants will usually survive on room light alone for a few months – to be safe, I set the terrarium light to go on for 2-3 hours during the cool of morning.

Plants as Waste Managers
I always fear downplaying the importance of regular cleaning, and it is not my intention to do that here. However, well-planted terrariums that are lightly stocked with animals are a delight to maintain.

The key is to have enough plants with vigorous root systems, live moss if possible and to find the right balance of plants and animals. The tank pictured here would actually be more easily maintained with just 2 gray treefrogs, or a single barking treefrog, as opposed to 1 of each, but I am familiar with its capabilities, and monitor it carefully. This terrarium has been up and running, with only two major substrate changes (one after housing a sick animal), for nearly 12 years.

Help From Snails and Sowbugs
In addition to the plants, I am assisted in tank maintenance by a thriving colony of land snails and sowbugs (Check Out: Terrestrial Isopods as Food for Captive Reptiles and Amphibians ). Both avidly consume the frogs’ waste products and decaying plant material, and neither requires additional food. The sowbugs provide an alternative food source for the frogs as well. I spot clean when necessary, occasionally replace the top inch of substrate, and change the pool’s water by wicking it out with paper towels. A layer of activated carbon below the substrate (an old trick now largely forgotten) helps to absorb nitrogenous wastes.

Feeding Native Treefrogs
Wild Caught Insects
My gray treefrog hatched in captivity, and the barker acts as though it did – both feed avidly from the hand. This allows me to more easily provide a varied diet, as they will take canned insects such as caterpillars and grasshoppers. From spring through fall, I feed the frogs exclusively upon insects that I trap with a Zoo Med Bug Napper or collect around my outdoor yard light. An insect or 2 each day or so suffices, and the dietary variety is key to good health (Check Out: Providing a Balanced Diet to Reptiles and Amphibians).

This is just a thought, but I believe it cannot hurt to attempt to provide arboreal and flying insects to tree frogs – especially so if you live within the range of the frogs that you keep. Mine favor moths, tree crickets, small katydids, caterpillars, beetles, harvestman (“daddy longlegs”) and flies. I avoid spiders, fireflies, ladybugs and brightly colored species, due to possible toxicity problems, and do not collect for a week or so after the area has been sprayed to control West Nile virus ( I believe the plane-sprayed insecticides kill far more cicadas than mosquitoes, but I digress…).

Commercially Available Insects
During the winter, temperatures in the terrarium average 62-65 F, the light cycle is reduced to 8 hours, and the frogs slow down. A once-weekly feeding of crickets (use only small ones for gray treefrogs), mealworm beetles, waxworms and earthworms holds them until tastier meals return (most treefrogs refuse earthworms, but some individuals will accept them).

I powder feeder insects with a vitamin/mineral supplement during the winter only – I’ve found such is unnecessary in summer, when wild caught insects dominate the diet.

The frogs and terrarium are sprayed once or twice daily with de-chlorinated water (both species use the pool as well).

There are 2 nearly identical species of gray treefrog in the Eastern USA. You can learn how to distinguish them, and a bit about the National Wildlife Federation’s laudable Frogwatch USA Program, at:
http://www.nwf.org/frogwatchusa/content_amphibianprofile.cfm

A newly discovered bacteria species (Deviriesea agamarum) is responsible for a variety of fatal organ diseases that currently plague captive lizard populations, according to an article in the September, 2008 issue of The International Journal of Systematic and Evolutionary Microbiology. Particularly hard-hit has been a breeding program for the highly endangered Oman dab lizard, Uromastyx thomasi, but a number of other desert-dwelling lizards in the genera Uromastyx and Agama are susceptible as well. The bacterium is related to others that cause human skin infections.The identification of the bacterium has important implications not only for the treatment of disease in captive lizards, but also for wild populations. Captive-bred reptiles that are used in reintroduction programs may appear healthy but harbor diseases that can decimate wild populations. Some years ago, this very situation caused serious respiratory disease outbreaks among desert tortoise populations in the American southwest, and led to a ban on the release of confiscated tortoises. Similarly, the September 23, 2008 issue of Current Biology states that many amphibian species in Europe are currently threatened by a fatal Chytrid fungus that was introduced to the wild by Mallorcan midwife toads released as part of a reintroduction effort.

You can read more about disease problems that affect reintroduction programs at:
http://esciencenews.com/articles/2008/09/22/captive.breeding.introduced.infectious.disease.mallorcan.amphibians.0