The fire bellied toad is strongly bound to water, being in it or near to it nearly all the time as compared to other toad species. It is diurnal as well as nocturnal and its period of activity streches from March until September/October.The males are sexually mature after the first overwintering, the females after the second. Mating season is between April and July and within this period the calls of the animals can be heard mainly while spawning. The call of young toads is higher than that of older ones.
Calls are used to mark the male bombinas territory and also to attract females. The male, floating flat in the water, fills its lungs with air and by making pumping movements with the bottom of the mouth then presses the air into his internal resonator through the soundmaking larynx and from thence back into his lungs again. During the call mouth and nostrils are completely shut. Floating plants are favourite calling places.
Fire bellied toads mate in water. The male clings on to the female in the area of her loins with nuptial pads, which he has on the inside of his forearms during mating season. Eggs are laid in form of masses of spawn on waterplants in a depth of 10 – 20cm. With each spawning 20 to 30 eggs are laid, measuring an average of 1.4 – 1.8mm. 200 – 300 eggs are laid per animal and year during the spawning seasons in early spring and summer.The larvae are approx. about 5.5 cm long and without outer gills and have a crest with a net structure. The upper crest is high and reaches all the way up to the first third of the back. On the top of the larvae yellow lines show from time to time. The tail is 1.5 times the head-rump length and the mouth is triangular (yellow bellied toads oval).
Insects and larvae, especially mosquito larvae, worms (tubificides) and snails are prefered by the fire bellied toad. All food has to be snapped, as the animal has no tongue.EnemiesDue to its ill tasting glandular secretion hardly any animal eats the awful tasting toad more than once in its life. When in danger the toad adopts the so called unkenreflex by pressing its back through very strongly and raising its fore and hindlegs. Now the red patterned belly can be seen which frightens off many enemies. Larvae and eggs do not possess this protection. Next to the watershrew, some birds such as the stork, brown owl or bittern, are enemies of the fire bellied toad.