How to keep...

Frogs and toads

Jan Verkade

INTRODUCTION

Bear in mind before purchasing a frog or toad that most prefer a sheltered habitat where they can hide from their natural predators. Many species are active at night so you may not see much of them in a terrarium.

Familiar nocturnal species are the 'true' tree frogs of the genus Hyla, which are found on all continents. The genera Agalychnis and Phyllomedusa from Central and South America, and the genus Rhacophorus from Asia are other well-known examples of nocturnal tree frogs. Some of the more frequently encountered diurnal frogs are the Central and South American poison-dart frogs and Mantella species from Madagascar.

Frogs from the genera Xenopus (from Africa) and Pipa (from South America) are completely aquatic.

SEXUAL DIMORPHISM

It is often difficult to determine the sex of the animals. In well-fed adult animals the females are often somewhat larger and more rounded than males. Sometimes the males can be identified by their darker throats, which indicate the presence of a vocal sac. In many species, breeding males have warty excrescences on the inner surfaces of the hands and lower arms. These are used to get a better grip on a female. In some poison-dart frogs, males can be differentiated from females by their wider fingertips. Unfortunately, it is often hard to find a telltale sign, and putting together a breeding group can be a real gamble.

TERRARIUM

The natural habitat of frogs and toads and their behaviour should determine how the terrarium is decorated. There need to be plenty of hiding places where the animals can retreat.

For aquatic frogs an aquarium with some rocks, a small piece of driftwood and a few aquatic plants will suffice. Terrestrial frogs and toads will need a layer of moist peat covered with some moss and beech leaves, a few branches for climbing, and some climbing and epiphytic vegetation. A small shallow water basin and daily spraying will provide the animals with sufficient water.

Because of the humidity it is best to construct the terrarium entirely out of glass. The separate windowpanes can be glued together using special transparent and waterproof caulking. A floor surface of 50x50 cm is an often-used standard size. For fervent climbers a height of one meter can be necessary, but often 50 cm will do.

The types of plants used determine the intensity of the lighting. Orchids, for example, require a lot of light whereas mosses and ferns make do with less. The most practical solution is to work with fluorescent tube lighting. The intensity of the light usually does not matter to the animals (they are nocturnal), but the regime of day and night does. Since many terrarium animals originate from the tropics it is recommended to keep the day length relatively constant, approximately 12 to 14 hours per day.

Ventilation is needed to keep the plants from rotting within a few weeks, and to have a separation between wet and dry spots inside the terrarium. A small screen in the top of the terrarium that is covered with a fine-mesh mosquito screen (small enough to keep fruit flies inside) and another about 5-10 cm above the floor in the front panel of the terrarium, ensure good air circulation. Because the circulating air moves along the front window it also prevents condensation. A removable or sliding front window simplifies the care of the animals. If more than one terrarium is placed side by side, a construction with two sliding windows, with one moving in front of the other, might be useful. Special profiles are available for this purpose from your local hardware store.

True aquatic frogs will need a water temperature of 20-25°C. Most terrestrial frogs and toads from tropical lowland regions need a daytime temperature of 23-28°C. At night the temperature may sink to 18 23°C. Animals from tropical mountain ranges (such as Gastrotheca species and most Atelopus) may be subject to temperatures that can be ten degrees lower. Mantella species from Madagascar can endure night-time temperatures that are lower than 10°C.

Frogs and toads from temperate zones, such as Hyla cinerea or Bombina orientalis are adapted to a summer and winter regime. Temperatures similar to Dutch summers are sufficient. During the winter, it is preferable to put the animals through hibernation for approximately two months at a constant temperature that needs to be well above the freezing point. This lowers the metabolic rate of these animals to such a level that they will not need any food. The cold resting period is an important stimulus to induce reproduction in the spring.

It is be necessary, especially with the 'warm' tropical species, to artificially heat the terrarium during the cold winter months. The most practical way to do this is by placing a thermostatically regulated heating mat or cable underneath the terrarium.

BEHAVIOUR

The behaviour of frogs and toads is an important factor in the decoration of their terrarium. It also determines how many individuals can be kept together in one terrarium. Remember that in some species, the males need their own territory, which they will defend vigorously against other males, even males of other species. Weaker males will be highly stressed and eventually die. There are some really bullies, especially among the more commonly kept poison-dart frogs. It is impossible to keep more than two males of these species together, even in a spacious and densely vegetated terrarium. Females are usually more tolerant and can therefore be kept together in small groups.

A good rule of thumb is to not keep more than one species in a terrarium. Preferably all animals should be roughly the same size. Frogs and toads basically eat anything that moves and fits inside their mouth. Horned frogs and larger tree frogs will rapidly consume smaller individuals of other species and even their own.

REPRODUCTION

Reproduction in frogs and toads is extremely varied. Aquatic species and many toads lay their eggs in the water. The number of eggs can vary from several dozen to over 20,000 per clutch. Other species attach their eggs to leaves of plants that overhang the water. Sometimes foam nests are created that allow the eggs inside to develop safely into tadpoles. Poison-dart frogs display sophisticated parental care in which one parent (usually the male) takes the tadpoles on their back and carries them to the water. Sometimes their care does not stop here ; once the tadpoles are deposited in a safe place, the mother will return every few days to feed her offspring unfertilised eggs.

Reproduction is usually seasonal. This can be in spring when the ambient temperature starts to increase. On the other hand, many tropical species commence reproduction at the onset of the rainy season. If rain is the stimulus needed to trigger reproductive activity, the terrarium needs to be prepared accordingly. A large water basin is needed from which a pump can direct water to the top of the terrarium where it 'rains' back down into the basin through a perforated tube. Because of their specialised breeding system, poison-dart frogs can reproduce year-round.

Tadpoles almost invariably need water for their development. Apart from an occasional species, they can all be reared on dry fish food. To prevent the water in the basin from getting polluted - which causes tadpoles to die - the water needs to be cleaned frequently. The larvae of some species can be raised in groups in a single aquarium. However, many species of poison-dart frogs have cannibalistic larvae and each tadpole needs to be in its separate container.

Depending on the species, the development of the larvae may take from 6 weeks to more than a year. The transition from tadpole to frog (metamorphosis) is a critical period. If an animal can not leave the water easily, it will drown. During their tadpole stage, frogs and toads breath through gills; when they become adults, they breathe through lungs. Juvenile frogs need a few days to have their mouths adapt to eating live prey. Young frogs and toads are often very small, meaning they are only capable of eating very small prey. During this period they require tiny fruit flies, 'dust' crickets or even smaller prey such as springtails.

FOOD

Frogs and toads are true carnivores. In addition, their prey needs to move, otherwise they will not recognise it as food, so that only live prey can be offered. Depending on the species and size of the animals, you can provide them with springtails, fruit flies, crickets, mealworms, earthworms or even mice. If you want to take good care of your animals, it is advisable to breed your own prey animals. This requires at least as much attention as the care of the frogs and toads.

Adult animals only need to be fed two or three times per week. The animals will remain active because they need to hunt for prey, which will benefit their physical condition. Juveniles always need to have access to sufficient amounts of food so they can grow uninhibitedly. Remember that in a terrarium situation the animals will not receive as varied a diet as they would in the wild. There is a definite possibility that a deficiency of minerals, vitamins or trace elements may occur. It is therefore recommended to dust the prey animals with a calcium-vitamin additive. Of course, dusting prey animals is pointless when feeding aquatic frogs and toads.

DISEASES

Healthy frogs should look lively, have an erect posture and a shiny, smooth skin. Toads normally have a warty skin that may be somewhat loose-fitting. Upon touch they will jump away directly or assume a hunched fright posture. However, immediately after they should resume their normal erect posture, with the body held high on the front legs (of course, many nocturnal frogs sleep in a hunched posture during the day, making it impossible to use this trick).

The animals should never be so skinny that their flanks appear indented, or the spine is showing clearly through the skin (in the leaf frogs of the genera Agalychnis and Phyllomedusa the waist does need to be very thin). Malnutrition can be the reason for such an appearance, but more often it is caused by a worm infection. You will not be able to see from the outside what the cause is. Remember that when an animal is in bad shape, treating worm infections and other diseases will be difficult. If an animal appears bloated, it usually indicates an infection with unicellular parasites. Such animals are often listless. However, there are exceptions : horned frogs (genus Ceratophrys) need to look like they are bloated. Both worm infections and infections with unicellular parasites can be treated. Liquid medication is available that can simply be applied to the animal's skin. Keep in mind that there may be other causes for losing weight or appearing bloated.

Skin lacerations often result in nasty infections that may prove fatal to the animal. There is medication available for such mishaps as well. Consult your veterinarian about the type and dosage needed.

MISTAKES

Too often animals are bought impulsively. A hastily prepared terrarium as a temporary home is a bad way to start. First prepare a terrarium and make sure that you have a well-stocked supply of captive-bred prey animals. Only then should you purchase the animals.

Many frogs and toads are kept too warm or too cold. Constantly disturbing the animals by looking for them, just because they don't show themselves, is another mistake often made by beginners. Frequently, too many animals or too many species are put in the same terrarium. Find information about the natural habitat of the animals and their behaviour before purchasing. This will help you determine the proper decoration, temperature, humidity and lighting for the terrarium.