The Fire Bellied Toad
(Bombina Species) FAQ

by Marc Staniszewski

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Belly of Yellow-bellied Toad
(Bombina variegata kolombatovici)


INDEX



INTRODUCTION

In Europe and southern continental Asia there are a number of small, warty toads that are amongst the most popular and comical of all vivarium subjects. Known as fire-bellied toads, the genus Bombina is composed of six species which show similarities in shape and habitat preferences but differences in size and coloration. They used to come under the family Discoglossidae which related to the lack of mobile tongue. However because of the stark differences in morphology, biology and behaviour, they were placed in their own family Bombinatoridae along with another little-known genus called Barbourula (Jungle Toads).

Classification
Order: Anura
Family: Bombinatoridae
Genus: Bombina
Species: European Fire-bellied Toad (Bombina bombina) Linnaeus, 1761
Species: Yellow-bellied Toad (Bombina variegata) Linnaeus, 1758
Species: Guangxi Fire-bellied Toad (Bombina fortinuptialis) Tian & Wu, 1978
Species: Giant Fire-bellied Toad (Bombina maxima) Boulenger, 1905
Species: Hubei Fire-bellied Toad (Bombina microdeladigitoria) Liu, Hu & Yang, 1960
Species: Oriental Fire-bellied Toad (Bombina orientalis) Boulenger, 1890


SPECIES SECTION

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European Fire-bellied Toad
(Bombina bombina)

The nominate form - the European fire-bellied toad (Bombina bombina) - has the greatest distribution of the four species ranging from the Central Balkans eastward in a wide belt across central and eastern Asia. It is also the smallest species rarely attaining more than 4cm and seems to prefer somewhat cooler, more shaded environments than the other species. The grey-brown dorsum is covered with many tiny spiked tubercles giving a rough texture in between which are located hundreds of tiny pores. The head is more pointed than other species and overall this toad has a distinctly pear-shaped build. As in other Bombina only the hind limbs are webbed and when in water the fronts limbs are either held decumbent to the sides or forward to aid direction. As the common name suggests the underside is a fiery red colour interspersed with black or grey blotches. Grey-white rimmed pores are also heavily in evidence. In some species, particularly where bloodworm, water shrimps, daphnia and other water crustacea are absent from ponds, the belly tends to be an orange or weak yellow colour. The association is that many freshwater crustaceans contain a naturally occurring substance known as canthaxanthin - a red carotene pigment which gives the toads their vivid red belly coloration.


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Yellow-bellied Toad
(Bombina variegata kolombatovici)

The yellow-bellied toad (Bombina variegata) is an entirely European species which occurs as several geographically divided subspecies (see table I). Although a small toad it is slightly larger and more stockily built than B.bombina with the forearms in particular being quite muscular. This toad enjoys long periods of sun basking but is rarely if ever found far from water. The dorsum is usually very dark, almost black although it is able to alter its colour according to its surroundings. The warty tubercles covering the dorsum and head tend to much smoother and more rounded than B.bombina and pores are not visible to the naked eye. The ventral coloration ranges from a vivid orange-yellow to a pale lemon depending on the subspecies and black, grey or dark blotches are either very evident (some individuals have totally black bellies) or totally absent (ie. the belly is completely yellow).


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Oriental Fire-bellied Toad
(Bombina orientalis)

The most colourful species is undoubtedly the Oriental fire-bellied toad (Bombina orientalis) with its grass green and black striated markings. This species inhabits the streams and ponds of warm, humid foothills throughout southern China, Thailand, Korea and other continental south-east Asian countries. Attaining a maximum size of 5cm, the belly is a beautiful intense orange with a network of black blotches. This is the most stream-lined species and the dorsum is not as heavily warted as in other species.

The Giant fire-bellied toad (Bombina maxima) is the 'largest' Bombina but still rarely exceeds 6cm. At first sight this Chinese species appears like a larger version of Bombina variegata but the belly is a deep carmine red and the dorsal tubercles tend to be more like the warts typical of Bufonid toads. It inhabits cool foothill ponds and slow-moving streams that are frequently surrounded by much vegetation.

I have personally never seen the Guangxi Fire-bellied Toad (Bombina fortinuptialis) or the Hubei Fire-bellied Toad (Bombina microdeladigitoria) so I cannot comment on these species.

The main reason for these toad's bright-coloured venter is to warn potential predators of their offensive taste. When disturbed the toads arch the vertebral line of the dorsum inwards to achieve a concave shape so as to reveal the edges of their bright bellies. The limbs are also held up and the head arched back. This posture is known as the 'Unkenrefkex'. When actually provoked or attacked then a second defensive phase comes into play where the toads flips on to its back to reveal the full extent of its warning colours. Should provocation continue the toad secretes a milky toxin from the hundreds of tiny pores located throughout its body and is thus coated. Once a predator tastes this toxin it will rarely if ever attack these toads again although grass snakes and other water serpents are known to attack and devour these toads without any ill effects.

Table I: Yellow-bellied Toad
(Bombina variegata) Subspecies

SUBSPECIES DISTRIBUTION DESCRIPTION
Bombina variegata variegata Western Europe (not Britain) to 4cm, black dorsum, southeast to the northern Balkans yellow and black venter
Bombina v.kolombatovici Scattered throughout Dalmatia largest subspecies occasionally attaining 5cm. Dorsum tends to be a light grey rather than dark.
Belly sometimes with bluish tinge.
Bombina v.scabra Southern Balkans 3 - 4 cm. Tends to have the highest proportion of black on its belly with yellow being spots rather than blotches. Spiny tubercles occasionally extend on to belly
Bombina v.pachypus Italy as far as the northern tip of Sicily 4 - 4cm. Belly may be completely yellow or orange-yellow with sporadic small white or blue spots

HOUSING & CARE

These toads represent the hardiest, long-lived and ostentatious of all amphibians. The best way to house them is as a group of 6 - 12 individuals in a medium-sized aqua-terrarium where they should have access to a body of water (its depth and temperature depends on the species) containing plenty of vegetation and an area of land (such as a flat-topped rock or brick) with a suitable basking spot. The water temperature during the active period should not be below 58F. and preferably be nearer (64F. for B.maxima, 72F for B.bombina, 75F. for B.variegata and 78F. for B.orientalis) while a 25 - 40W spot lamp located 10 inches above the basking area will provide temperatures in the region of 74 - 85F. which is essential for rapid and proper digestion and also promotes breeding. A mesh top to the aquarium permits good ventilation and additionally a natural daylight tube should be present to allow water plants to grow healthily. Where a water filtration system is utilized the water should be completely replaced every four weeks because these toads expel large amounts of waste, otherwise every fortnight is necessary. In both cases the entire aquarium should be thoroughly cleaned every six weeks and a partial water change (approximately one third of the total water volume) take place once or twice a week. These toads will also live successfully outdoor either in a garden pond with a small island and adequate protection from cats and birds, a walled outdoor enclosure with a pond, or perhaps most notably in a greenhouse environment.

Typical Indoor Aqua-terrarium
for Bombina Species

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FEEDING

During the active period these toads will continually capture a devour many invertebrates ranging from crickets, waxworm, earthworms, mealworms and sweepings (brushing a butterfly net through a meadow or grassy area will trap a wide range of insects). The secret is to provide a wide range of foods which should be occasionally supplemented with a special herptile multivitamin powder. I like to occasionally give my own specimens strips of raw fish (white baits) and lean red meat or chopped pink mice offered on tweezers. Adult B.maxima will even take whole pink mice but this should not exclusively form the diet.

BREEDING

If given suitable stimuli fire-bellied toads will breed regularly throughout the courtship season, the most critical being a cool rest period for a duration of at least six weeks. It must be understood that only healthy individuals with sufficient body fats should be allowed to fully hibernate (not B.orientalis) and this can be implemented my moving the toads to another escape-proof, ventilated aquarium packed with damp (not sodden) sphagnum moss into which they will burrow. It can then be located in an unheated garage, shed or attic where temperatures do not fall below 35F. Otherwise the toads can remain in their aqua-vivarium where extra land covered with sphagnum moss should be added, the temperature lowered to around 44F. and the spot-light switched off. The toads will refuse food and spend most of their time hiding beneath the moss. Following the cool period, raise the water temperature by 1 - 2F. each day and the switch the spot-light for increasingly longer periods of 10 minutes until the peak temperature and 14 hour photoperiod (daylight) are achieved. During this time the toads will become increasingly more active and hungry. The aquarium containing hibernating toads should initially be located somewhere at room temperature for a few hours and then the toads can be introduced back into the aqua-vivarium when the water temperature has reached about 55F. For Bombina orientalis, simply lowering the water and air temperature to around 60F. during the cool period is adequate because these toads are susceptible to low temperatures. Breeding should commence from mid-May particularly immediately after rainfall (which can be simulated by undertaking partial water changes with a fine-rosed watering can) when male toads float on top of the water with all legs splayed out and commence their characteristic calling. In B.variegata this is a slow 'poo-poo' sound lasting for 10 - 25 seconds; B.bombina has a slightly faster 'oop-oop-oop' which can transcend for 30 seconds; B.orientalis sounds like the gentle tapping of a musical triangle - a 'ting-ting' sound which rarely lasts longer than 15 seconds and the call of B.maxima is similar to, but deeper and more resonant than B.variegata. Mating usually commences at nighttime with males grasping the females just in front of the hind limbs, a position known as lumbar amplexus. To aid their grip, males are equipped with rough, horny nuptial pads on the inner thumbs although unresponsive females are inevitably able to squirm their way out. Such is the frenzy that males will often work themselves into, they will accidentally grasp on to anything that looks remotely worth mating with including floating twigs, plants, other anurans, newts, fish and even fingers. Their is nothing more comical in the amphibian world than to observe an unfortunate male make a wrong move and suddenly be besieged by half-a-dozen desperate males. Incidently to promote vigorous breeding in Bombina it is recommended to establish a ratio of one female to two or three males. Another factor in achieving successful amplexus is the perspective of the breeding pond. B.variegata and B.orientalis prefer an open, shallow (2 - 6 inches) pool containing lots of submerged water plants that it is in a very sunny position so that its temperature increases rapidly during the day. B.maxima also appreciates an open pond which has both deep (12 - 18 inches) and shallow regions (ie. a cool to warm gradient of water). B.bombina presents the most difficulties as will often refuse to breed even when seemingly ideal conditions exist. In my own experience a large aquarium which half-shaded, half sunny pool of medium depth (8 - 10 inches) containing cool water and plenty of submerged and surface pond plants such as zebra quills and parrot feathers plant may prove fruitful.

Eggs, Tadpoles & Toadlets

If mating is successful females will deposit their 40 - 110 eggs either individually or in small clumps of 4 - 25 eggs very close to the water surface where the warmth of the sun (spotlight) can aid embryo development. It is advisable to remove the eggs to a separate 90cm aquarium (per 100 eggs) containing 20 - 30cm of cool (60 - 65F.), well-oxygenated and most importantly fresh water. Within 5 - 8 days the 6mm black tadpoles hatch out to spend the first week of their life clinging inanimately to the glass sides, plants or rocks while absorbing their yolk sac. Development is quite rapid and within a fortnight tadpoles will be 20mm and using their cusp-like mouthparts to feed on strips of raw meat, trout pellets, fish flake and chopped earthworm. Bombina tadpoles are very distinctive on close observation; they have a projection from the belly called a spiracle which is in effect a gill opening, and the cream coloured intestines are visible through the ventral surface. B.bombina tadpoles also have a triangular shaped mouth; in B.variegata it is more elliptical while in B.maxima and B.orientalis it is almost round. During such quick growth large amounts of waste are expelled with partial and complete water changes recommended every 2 - 3 days and 2 weeks respectively. After 6 - 8 weeks hind limbs begin to appear, one from the spiracle which marks the beginning of lung development. Tadpoles can frequently be seen surfacing where they will take gulps of air. In B.maxima tadpoles their will already be signs of the fiery belly. Tadpoles will have reached their peak size; 3 - 4cm in all species except B.maxima whose tadpoles are surprisingly just 2 - 3cm.
After 8 - 14 weeks the tadpoles enter a critical phase when they begin to metamorphose into a fully air-breathing amphibians. In all species the characteristic belly pigmentation becomes visible - weak lemon coloured in B.variegata, orange-yellow in B.bombina and B.orientalis. At this point the water must be lowered to around 4 - 8cm and plenty of easily egressible rocks and logs must be provided.

Toadlets climbing onto land often have large remnants of the fleshy tail existing and remain semi-aquatic for several days thereafter. They are quite minuscule, just 7mm in B.maxima to 12mm in B.orientalis.
For the first few weeks of their land-based life Bombina toadlets can prove quite difficult to raise. They are best removed to plastic ice-cream tubs with a secure but well-ventilated lid containing a base of soaking kitchen tissue paper. Initially they require very small foods such as aphids, fruit fly, whiteworm, hatchling crickets, bloodworm and hatchling waxworm which should be offered as regularly as possible. Frequently dusting the food with a proprietary multivitamin powder can also prove advantageous. After 4 weeks the toads will be 15mm in size (18mm in B.orientalis) and over the ensuing weeks B.maxima will begin to grow more rapidly. All species except B.variegata should be given plenty of water crustaceans and bloodworm to promote the orange/red coloured belly.

Maturity can be attained within 8 months if feeding is particularly varied and nutritious otherwise 14 - 22 months is more typical. Besides being very tolerable, these toads are one of the longer living anurans frequently attaining 12 - 15 years, often longer in the European species.





Literature Cited;

Amphibians in Captivity (TFH) - Marc Staniszewski (1995)
A Field Guide to the Reptiles and Amphibians of Britain and Europe (Collins) - Arnold/Burton 1980
Frogs & Toads of the World (Cassell) - Chris Mattison 1987


You can e-mail me at: marcstan@amphibian.co.uk

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All text and photo's - Copyright 1996-8 Marc Staniszewski
Most recent revision: 30/09/98

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