Facts about this animal
The Yellow-bellied Toad is 28-56 mm long and slightly depressed. It may weigh 2.3-12 g. The snout is rounded. Above, the skin is densely covered in tubercles with black horny spines. There are no parotids behind the eyes nor are the eardrums visible or vocal sacs present. Webbings are well developed at the hind feet. The pupil is heart-shaped, and the iris is brownish. The body colour is grey or olive-brown on the upper side, sometimes with pale paired spots on the back. The ventral side, however, is strikingly marked bluish-black with irregular yellow blotches or spots (and tiny white dots) in order to warn enemies. Either colour may dominate.
The skin produces a poison to protect itself from bacteria and fungi or the animal from vertebrates. This poison is irritating to mucous membranes and is called bombesine, a cardioactive peptide, which has a low pH and lowers blood pressure as well as blood sugar. The eggs are brown above and lighter below. They are 1.5-2 mm large coated with a transparent but often mud-covered jelly of 5-8 mm in diameter. Tadpoles are up to 55 mm long and have a blunt tail. They are greyish brown with dark spots or, rarely, colourless and transparent which is a good camouflage in an environment without shelter. The flipper is cross-hatched with dark spots and the mouth field is oval.
The Yellow-bellied Toad can be found throughout the day but is most active by night. During day it often hangs vertically in the water just keeping the nose above the water level. On land, it feeds on worms, slugs and arthropods like insects, millipedes and spiders, in the water, on insects like midge larvae or amphipods. The tadpoles graze algae from stones or from the bottom. If attacked by a vertebrate on land the Yellow-bellied Toad makes a hollow-back and lifts its four legs so that the ventral warning colour is displayed. The combination of dark and yellow is a learned signal meaning “attention poison” to the enemy.
During reproduction period, which last from April to August, males can be recognized by some darkened, spiny swelling, the nuptial pad, on their forelegs. They help it to grasp the female properly around its hip. The 2-100 eggs are laid in a clutch or rarely singly. They may be attached to plants or not. With repeated spawning, especially after heavy rain has produced new suitable bodies of water, a female can produce 120-300 eggs during one summer. Tadpoles hatch after 2-4 days. They can withstand water temperatures of 36 °C, high levels of nutrients and even short desiccation. Larval development just takes 41-67 days. After metamorphosis the young toads are 12-16 mm long and remain in the water to the end of the summer. Later, they disperse to colonize new habitats in a distance up to 4 km away. The call is low and dull like blowing into a bottle and is repeated more than 40 times per minute. It is performed if water is at least 11-14 °C warm. Rivals are driven away at a distance of up to 1.5 m. On land, the Yellow-bellied Toad hibernates in hollows, in water, buried in the ground. Maturity is reached at the age of 2 year. Till then the young try to colonize new habitats. The Yellow-bellied Toad can reach an age of 15 years which is necessary because its reproductive habitat may be dry during several consecutive years.
Loss of natural dynamic and intensification of agriculture are the main threats for the species.
Hybridization with the European Fire-bellied Toad may occur where both coexist.
Did you know?
that the Yellow-bellied Toad does not flip on his back to display his ventral warning colours but just makes a hollow-back lifting al its feet? that the Yellow-bellied Toad is endangered in Germany, Austria and Switzerland? that in captivity a Yellow-bellied Toad reached an age of 27 years? that, rarely, tadpoles of the Yellow-bellied Toad can grow to giants of 100 mm if they are not able to metamorphose?
|Name (Scientific)||Bombina variegata|
|Name (English)||Yellow-bellied Toad|
|Name (French)||Sonneur à ventre jaune|
|Name (German)||Gelbbauchunke, Bergunke, Berglandunke, Gebirgsunke|
|Name (Spanish)||Sapo amarillo-hecho bolso|
|Local names||Croatian: Žuti mukac
Czech: Kunka žlutobrichá
Hungarian: Sárgahasú unka
Italian: ululone dal ventre giallo
Polish: Kumak górski
|CITES Status||Not listed|
|CMS Status||Not listed|
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|Range||It is distributed, with three subspecies, from France and southern Germany south to Northern Italy and the Balkans.|
|Habitat||Reproduction in temporary, shallow, sunny and warm muddy pools with little vegetation along natural rivers or in military areas, in gravel or clay pits with land-slides, also puddles and wheel tracks. Otherwise nearby the water or in clear forests where humidity is high and enough hiding places are found. Hibernation on land or in water. Up to 2'100 m in Bulgaria.|
|Wild population||Habitat loss is the main threat to this otherwise not rare species. In Germany the species is endangered to locally extinct.|
|Zoo population||31 reported to ISIS (2008)|
In the Zoo
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Why do zoos keep this animal
The Yellow-bellied Toad is remarkable because it has camouflage colours on its upper side as well as warning colours on its ventral side. Displaying the latter it warns its enemies from the poison on its skin. It also can be used in education to show its complex life cycle. Concerning the global amphibian crisis it is compulsive to breed them in captivity (Amphibian Ark). Zoos are qualified and comparably well adapted to do this.