Brown Tree Frog
Brown Tree Frog (Litoria ewingii)
The Brown Tree Frog is a slender species characterised by a dark brown to sandy grey-brown upper surface with a broad darker brown patch flanked by a darker brown to black stripe running the length of the back. The under surface is white. The adult female reaches 45 mm, the male reaches 37 mm.
These frogs like to utilise the height of the available cage and so a minimum enclosure of 45cm height x 30cm x 30cm is recommended to house 2-3 adults. These frogs like to climb up the glass and the height of the cage is far more important than the floor space. The base of the terrarium should be kept moist at all times and have a good supply of water as these frogs like to sit in a shallow edge rather than swim (which they do ocassionally) an area about 10cm x 3cm deep will be sufficient. To create more bio active environment a layer of gravel to 3cm topped with another 4cm of dirt may be used, as the frogs don’t like dirt cover it with sphagnum moss, add rocks and branches for them to climb on Pot plants or ferns can be used just ensure the pot plants are safe for amphibians. A good indicator of good conditions is if the moss is thriving, Spray the enclosure in fine water mist daily and the frogs will enjoy it.
Temperature / Heating
Brown Tree Frogs should be kept indoors to protect them from the exposure of extreme temperatures. No heating is required for this frog but can be added if temperatures fall below 10 Celsius. Ideal temperature range for this particular species of frog is a minimum of 10 Celsius and a maximum of 25 Celsius.
Brown Tree Frogs are nocturnal in the wild but can be quite active during the day in captivity. No UVB lighting is required but you will require one if you want to keep live plants in your terrarium. An 8 hour light cycle is recommended. DO NOT EXPOSE THE HOUSING TO SUNLIGHT.
Maintaining water quality is an important part of keeping your frogs healthy. Chlorine will need to be removed from your tap water and the best way is with some Repti Safe. Your water should be changed regularly which will depend on how much water you have and how many frogs you have. A small filter, running water and some aquatic plants will all help to keep your water clean. Only change up to 50% of the total water volume at any one time and do not use hot water from the tap. Although Frogs can easily climb glass, it is important to provide numerous escapes from the water especially in the corners where young frogs tend to get trapped. Small frogs are often too weak to break the surface tension of the water when they have nothing but slippery glass to cling to. Part of or all of your tank may be covered in water.
In nature most frogs are almost totally insectivorous. In captivity the tendency to use substitute foods is one which must be avoided. The most common dietary problems seen in frogs are related to lack of calcium or too much protein in the diet. Calcium powders are available from o ur store and should be mixed in equal quantities with a multivitamin powder then dusted on food before feeding. Place your food insects in a plastic bag with a pinch of calcium/multivitamin powder and shake it till the food is well coated. By doing this about 1/2 the times you feed your frogs, calcium deficiency will be avoided. Feed your frog a variety of insects and invertebrates and you should have few diet related problems. Juveniles will happily eat flies, moths, small crickets and cockroaches, and should have food available to them AT ALL TIMES. Adults will eat almost anything that moves and fits in their mouth, they should be offered about 10-20% of their own body size in food spread over 2-3 feeds each week. During winter or when your tank temperatures are reduced your frogs will need less food. It is important to increase and reduce food in both quantity and frequency with the changing temperatures of your enclosure. Remove drowned insects so as not to foul the water, or feed your frogs individually by holding the insects on some feeding tongs.
Breeding occurs in early spring and autumn. Small eggs are laid in several clusters, totalling 500 to 700 eggs. Eggs hatch four to six days after laying. The larval stage lasts for up to seven months in colder waters. Tadpoles reach 60mm before metamorphosis occurs in spring, summer or autumn. Sexual maturity is reached within a year.
Using temperature treatment to reduce chytridiomycosis infection
Four of five studies (including four replicated, controlled studies) in Australia, Switzerland and the USA found that increasing enclosure or water temperature to 30–37°C for over 16 hours cured frogs and toads of chytridiomycosis. One found that heat treatment at 30–35°C for 36 hours did not cure northern leopard frogs.
Background information and definitions
Treatment of chytridiomycosis is vital to ensure the success of amphibian captive-breeding programmes. Also to reduce the risk of spreading the disease when animals are moved between captive or wild populations.
The chytrid fungus Batrachochytrium dendrobatidis is very sensitive to temperatures above 32°C. At 37°C the fungus is killed within four hours and at 47°C within 30 minutes (Young et al. 2007). A study found that the probability of infection by chytrid in the wild decreased strongly with increasing time spent with body temperatures above 25°C in three frog species (Rowley & Alford 2013). A study in captivity also found that fewer frogs became infected and died when exposed to the chytrid fungus if they were housed at 27°C rather than 17°C or 23°C (50 vs 100% mortality; Berger et al. 2004). Increasing temperatures within amphibian housing may therefore provide a treatment for chytridiomycosis.
Berger L., Speare R., Hines H.B., Marantelli G., Hyatt A.D., McDonald K.R., Skerratt L.F., Olsen V., Clarke J.M., Gillespie G., Mahony M., Sheppard N., Williams C. & Tyler M.J. (2004) Effect of season and temperature on mortality in amphibians due to chytridiomycosis. Australian Veterinary Journal, 82, 434–438.
Rowley J.J.L. & Alford R.A. (2013) Hot bodies protect amphibians against chytrid infection in nature. Scientific Reports, 3, 1515.
Young S., Berger L. & Speare R. (2007) Amphibian chytridiomycosis: strategies for captive management and conservation. International Zoo Yearbook, 41, 85–95