Bombina variegata (Linnaeus, 1758)

Adult Size

Adult specimens of Bombina variegata range from 28 to 56 mm in length, and typically weigh between 2.3 and 12 g. This makes the species one of the smaller members of the family Bombinatoridae, whose members can reach up to 7 cm in size.

Dorsal Coloration

The dorsal (upper) side of the yellow-bellied toad is grey-brown, and often bears faded, bright spots.

Ventral Coloration

The ventral (under) side, including the inner surfaces of the limbs, fingers, and toes, is grey-blue to black-blue, with prominent bright yellow to orange spots or patches that usually cover more than half of the underside.

Body Shape

Yellow-bellied toads have compact bodies – though not as flattened as their close relative the European fire-bellied toad – and a rounded snout.

Head Features

Their pupils are heart-shaped, and their eardrums are not visible.

Dorsal Skin Texture

The dorsal side is covered in numerous warts with raised swirls.

Sexual Dimorphism

A study by researchers from Brill Academic Publishers found that this species has sexual dimorphism: males have a notably longer humerus, which results in longer forelimbs. This longer forelimb length is thought to give males an advantage during mating coupling and fights with other conspecific males.

General Distribution

The yellow-bellied toad inhabits mountainous regions, primarily in Western Europe.

European Bombina Species

Two Bombina species occur in Europe: Bombina variegata and Bombina bombina.

Population Abundance Trends

Following postglacial range expansion of Bombina bombina, Bombina variegata populations have become less abundant. Yellow-bellied toad populations are also restricted to much smaller, more isolated geographic areas.

Specific Range Countries

The most common regions where the toad is found include France, Germany, Belgium, and the Netherlands.

Habitat Impact

Habitat disturbances have caused a significant decrease in the species' area of occupancy.

Female Reproductive Capacity

Female yellow-bellied toads are physiologically capable of producing offspring multiple times per mating season, and the species can produce long-lived individuals. However, it is rare to find females that actually produce multiple clutches of offspring per year.

Clutch Size

Female reproductive output is also very low: while females are capable of laying over 200 eggs in a single clutch, they typically only lay around 40 eggs.

Clutch Size Evolutionary Explanation

This lower output is explained by the lack of evolutionary incentive for larger clutches when adult survival rates are high, while offspring survival rates are more variable.

Tadpole Size and Development Rate

Yellow-bellied toad tadpoles develop rapidly, and can reach 55 mm in length.

Tadpole Appearance

They have a blunt tail and are typically grayish-brown, or transparent in rare cases.

Offspring Predators

Both tadpoles and eggs are vulnerable to predation from various small pond-dwelling organisms, including leeches, fish, and some aquatic beetles.

Temperature Effect on Tadpole Development

A 2016 study published in the Canadian Journal of Zoology found that tadpoles developing in warmer water develop faster than tadpoles in cooler water. These temperature conditions mimic the differing environments found in forested areas and sunny quarries, respectively.