When it comes to amphibians that are kept in captivity today, the most popular by far are the frog species. Within the Hylidae family, there are about thirty-six genera of frogs. There are possibly more genera, partly because the taxonomy of the Amphibia class is one that is highly dynamic and constantly changing. Within this article, I will cover the basics as well as some advanced techniques for care of one of the more popular and easier kept species, known as the Green Tree Frog Hyla cinerea.
Schneider originally described Hyla cinerea in 1799. They are found natively in the Eastern United States from Southeastern Texas, Florida, and up into parts of Eastern Kentucky[i]. Their natural habitat is can be described as marshes, lakes, and ponds. Within their native areas, some consider them a back yard or everyday species. Today in these native areas you can readily find them for sale at almost all retail pet locations.
The Green Tree Frog Hyla cinerea are small frogs measuring 1 ¼ to 2 ¼ inches in total length. As the name implies they’re green in color but different populations may also have some variances within color. The coloration can be olive, to bright lime green. They also can change their color in response to temperature and possibly the lighting that they receive. Some have yellow or white spotting about the dorsum, which may be brighter in some specimens. Typically, they all have a white, cream, or yellow stripe that runs from the jaw to the hindquarters. I have seen some with this stripe in a silvery tone and others without this stripe at all.
To say there are many variances within the species would be an understatement at the least. But the fun doesn’t stop here. There are the occasional albino Green Tree Frogs Hyla cinerea produced through captive breeding as well as the coveted Axanthic or Blue strain. With that said, I have looked for the Axanthic strain and have seen photos but have never seen one live nor have I been able to find them for sale. I haven’t read any documentation of what ever occurred with the Axanthic strain but I would presume that it was a trait that was not genetically passed on or one that for whatever reason simply could not be reproduced in captivity.
Which Froggy in the Window?
When going to purchase a H. cinerea Green Tree Frog there a few characteristics to look for that can be very helpful to make sure you select one that is healthy. Look for one that is filled out where the bones aren’t showing through the skin. In other words, the frog should not be emaciated in any way. If possible, look for the stool within the enclosure that you are planning on selecting from. If you see runny or bloody stool do not purchase a frog from that enclosure. Ask to handle the frog before purchasing it. When it is in hand, look carefully at the underside and nose for any redness or sores. This is generally a sign of either a bacterial infection and or that there are too many frogs in one enclosure. Snout rubbing is often seen in amphibians when they are either overcrowded or are not given a large enough enclosure.
Even the most frugal people (like me) who are interested in keeping H. cinereacan easily meet their captive requirements. I will first lay out the minimal requirements of their captive environment and then I will detail what is in my opinion the most interesting environment. Never handle any type of amphibian unless it is absolutely required and even then, I would suggest using rubber latex gloves that have been moistened with reverse osmosis water. The reason for this is that the oils and other such things on our hands might be toxic to our pet amphibians. The two ways to keep H. cinerea are the basic “breeder” environment and the more expansive natural vivaria which includes live plants.
Basic “Breeder” Enclosure
For the basic enclosure, you can use a twenty-gallon aquarium with a screen top. Smaller enclosures do not allow enough space for the normal activity of this species. If you want to keep more than one per enclosure then I would recommend no more than 3-4 adult frogs per 20 gallon enclosure size. This will reduce the competition for food and allow all of the frogs to have their own space.
Within this enclosure, you can place a simple potted plant such as a Pothos Epipremnum, Chinese evergreen Aglaonema, or Philodendron sp. Any of these plants can be easily placed inside while in their pot or instead placed in a jar of water, either of which would be left free standing inside the enclosure itself. The substrate is most often used in this type of enclosure is newspaper. You can also use brown butcher paper, as well as non-dyed paper towels. This type of enclosure typically does not retain a high humidity, which might prove to be problematic. Should you live in an area which does not typically have at least a humidity of 70%, counteract this with a cool air humidifier for the room or try adding more jarred plants with water.
The naturalistic vivaria for the Green Tree Frog H. cinerea is the one that I prefer. The reason for this is two fold. First I think that all captive animals should be kept in an enclosure that is as close to their naturalhabitat as possible. Secondly, I am of the opinion that they display more natural behaviors when kept in a naturalistic vivarium as opposed to a basic set-up. I will only mention that there are many more options open to the keeper when setting up such an environment. Naturalistic vivaria consist of several elements, “true” substrates, live plants, climbing/basking branches, and lighting. A twenty-gallon enclosure can be used for the naturalistic vivarium as well, but I generally recommend one which is slightly larger, such as a twenty-nine gallon with a secured screen top.
When keeping Green Tree Frogs H. cinerea in a naturalistic vivarium it is always important to consider all the options that are available for substrates. I will go through each and offer the reasons that I do or do not use certain types. However, the final choice is yours and this article should only be considered as a guideline. The first substrate that can be used is medium grade pea gravel. I personally do not use this substrate, as it is not aesthetically pleasing to me. However, if this is a substrate that would be an option to you be sure that the size that is used is not one that could be ingested by the frog during feeding. Within this substrate, many plants can be grown hydroponically. You can also increase the humidity easily by filling the gravel bed with water. Typically filling water halfway up a 2” gravel bed will increase the humidity enough, to achieve the desired level.
Orchid bark or Ground cover bark can also be used as a high humidity substrate, which the frogs can not ingest. Should you choose this option you should make sure to mist the enclosure one to three times a week to make sure that thehumidity level is sufficient. If plants are added they should be left in the pots they came in and given some type of plant lighting to help them maintain proper growth. Once again, I do not use this set-up because the look of pots is not particularly appealing to me.
Potting soil is another option that is available and is a good choice because we can place the plants directly into the soil. This type of substrate can be toxic though because it doesn’t drain particularly well unless it placed on top of a gravel bed. The toxins, specifically ammonia from the Frogs urine, can build up underneath and because the frogs skin is highly permeable can lead to problems.
Commercially available substrates are available from several different manufacturers and depending on your personal taste might be just what you are looking for. Zoo Med® has several options available at most retail pet shops, as does T-Rex®. Both share the same claims that they were specifically designed for use with frogs and amphibians. It has been my personal experience that if you are going to construct a live plant vivarium then the product produced by T-Rex® known as Jungle Bed is the best one to use. I have used this particular product when constructing numerous planted vivariums and have never been disappointed in the growth of the plants or the humidity levels.
With all the plants available from home improvement stores and pet stores alike, it may be a disconcerting task to try to select those, which you and your pet might enjoy. Therefore I will list the ones that I have used successfully. Most if not all the plants that you should select will be what are known as indoor houseplants. The reason for selecting these types of plants is that they are typically smaller, and require less light than those that would be grown regularly outdoors.
Pothos Epipremnum, Chinese evergreen Aglaonema, Philodendron, and Arrowhead Sygonium are in my opinion the best choices when it comes to a live-planted vivarium. Pothos Epipremnum come in either solid green or a variegated variety and are a long vine type of plant which should be allowed to dry out between watering times. It is not particular about the humidity and does well under low light conditions, which make it a perfect candidate for thevivarium.
There are four different species of Aglaonema sp. The one known as Chinese evergreen is Aglaonema modestum, which does well in all types of lighting but prefers the soil to be wet. The Chinese evergreen Aglaonema modestum can grow to heights of 2’ and has 8” long leaves, which the frogs will rest upon making an extremely nice display. Philodendron scandens is the most commonly used Philodendron in the planting of vivariums. It is often sold as Heartleaf Philodendron. This particular species does well in low light and does well in temperatures of 70-85˚F. The leaves are 2 to 4” in length, are dark green, and as the name implies heart shaped.
Heating and Lighting
I have included heating and lighting into the same sub-heading because essentially they do end up going together most of the time when discussing reptiles. With H. cinerea Green Tree Frogs however, this is a different case altogether, as we will see. Because they come from the Eastern United States, they do not require heating ranges that most of our exotics require. The Green Tree Frogs H. cinerea do best at temperatures between 78˚ and 85˚ F at the basking area. The rest of the enclosure should be maintained at 70˚ F mark.
To achieve this I personally use a low wattage ceramic heating element that maintains the needed temperature at a specific site without disturbing the normal circadian rhythm. This is because recent studies have shown that our reptile and some amphibians can actually see the red wavelengths in light that are put out by the incandescent red lights that are typically used by most herpetoculturists. Although the ceramic heating elements are slightly more costly they do seem to last longer than the incandescent bulbs which wear out quickly through continuous turning on and off. You could also use a pulse proportional thermostat with either the red incandescent bulbs or the ceramic heating element however these are costly and do not seem to be a necessity if you monitor temperatures carefully.
When it comes to daytime needs of the vivarium, it may surprise some readers that I actually recommend some type of UV bulb be used. Even though H. cinerea Green Tree Frogs are crepuscular or nocturnal, depending on whose report you read, I am of the opinion that this allows for better psychological health when it comes to the maintenance of this and all other species of amphibian. Not to mention of course, that the UV lighting is still required by the plants that I have suggested earlier. Simply because they are “shade” plants does not mean that they will grow without light. It has been my experience as well that when the UV light is on an inexpensive timer this allows for a normal day and night cycle that the frogs themselves seem to figure this out and begin their nightly or daily routines in synchronicity with the light.
When it comes to the feeding of H. cinerea Green Tree Frogs there is little debate as to what is and what isn’t a proper diet. As with most Hyla sp., they should be fed a regimented diet of Gray Crickets Acheta domesticus. Typically, I feed about five Gray Crickets A. domesticus per frog every other day. Some keepers claim that they have had success feeding Mealworms Tenebrio molitoras an occasional treat to their H. cinerea Green Tree Frogs. I have personally never had success trying to feed these. It appears to me that the frogs are highly dependant on the movement of the Gray Crickets A. domesticus in order to find the food.
If this were something that you would like to try with your frogs then I would do so in a small dish that could be placed within the niche of a branch or another such place where it was not on the substrate itself. This would, in my opinion be a more natural setting where H. cinerea Green Tree Frogs would most likely see the prey item and be more likely to consume such fare.
Any insects that are fed to your frogs should also either be gut loaded or at minimum dusted with a calcium/multivitamin supplement of some kind. There are many arguments which go back and forth for which of these is better in my experience, unless you have multiple insect eating reptiles and amphibians it is easier to simply dust them with a multivitamin twice a week and then alternate to a calcium dusting twice a week. When dusting apply the dust with just a light coating meaning shake the powder onto the Gray Crickets A. domesticus and shake the bag if there is powder left over in the bag then the next time you feed try using less.
When it comes to the maintenance of H. cinerea there are really only a few major points of concern. Daily the water must be changed. This is not something that can not be overlooked, as all amphibians absorb water through their skins. Fouled water is one of the biggest causes of health related complications when it comes to amphibians of all species. Once a week I will wipe down the glass with Reverse Osmosis water and remove any fecal material that is visible.
During the summer and spring months when the air is somewhat dryer, I will spray the entire vivarium about twice a day. This should be done with Reverse Osmosis water as tap water generally leaves water spots and a film, which seemingly can not be removed if used continuously. During the fall and winter months, I spray less often as I do not want to lower the temperature too much, beyond what they might be used to in the wild.
Green Tree Frogs H. cinerea are great introductory species to the world of frog keeping and are in my opinion a great display amphibian which deserves more than a passing glance. Whether you are a seasoned herpetoculturist or someone who is thinking of possibly getting into the world of keeping reptiles and amphibians I would highly recommend this species. This is a frog, which is easily cared for and may lead you to discover that you may want to go further into the world vivariums and possibly even opening the door for you to begin keeping more difficult species of amphibians later.
Special thank you to John F. Taylor for allowing us to post this great caresheet. Please visit his website at www.reptileapartment.com