Common toads secrete an irritant substance from their skin that prevents most predators from eating them. Unfortunately for the toads, a few predators, such as grass snakes and hedgehogs, do not seem to be deterred by this irritant.

Life span
Common toads can live for up to 40 years.

Statistics
Body length: 8-15cm. Males are smaller than females.

Physical description
Common toads have a broad, squat body, with short toes, webbed hind feet and a rounded snout. Their eyes are orange with black horizontal pupils. They are covered in raised warts, particularly on the back and sides. Their skin colour varies according to time of year, area, sex and age. They can be dark brown, grey, olive, terracotta or sandy coloured, with a grey-white underside, and are sometimes covered in darker markings on their backs. They have two prominent glands behind the eyes, which produce a foul-tasting and irritating secretion. Common toads do not have an external throat sac. Males have thicker forelimbs and shorter fingers than females, and can be easily distinguished by the dark-coloured nuptial pads on the inner three fingers of their forelimbs. These pads become more prominent during the breeding season.

Distribution
Common toads are widespread in mainland Britain, but are absent from Ireland. They can be found over most of Europe, northwest Africa and Asia.

Habitat
Common toads inhabit damp areas of deciduous woodland, scrub, gardens, parks and fields. In the breeding season, they live in ponds, lakes, ditches and slow-moving rivers.

Diet
Common toads are opportunistic feeders, catching invertebrates such as insects, larvae, spiders, slugs and worms, on their sticky tongues. Larger toads also prey on slow worms, small grass snakes and harvest mice, which are swallowed alive. Toads can sometimes be seen in the daytime following rainfall, but they are generally nocturnal, being most active on rainy nights.

Behaviour
Common toads are solitary, except during the breeding. They excavate a shallow burrow, which they return to after foraging for prey. They are nocturnal and shelter under tree roots, stones and vegetation during the day. They shed their skin regularly, and often eat the sloughed skin. Contrary to popular belief, they tend to walk rather than hop. Common toads hibernate in October, typically under deep leaf litter, logs, timber piles, or in burrows and drainpipes. They will occasionally hibernate in mud at the bottom of a pond, but tend to live away from water except during the breeding season. They emerge from hibernation in spring (late March) and migrate to breeding sites.

Reproduction
Although males usually wait for females at breeding sites, they will sometimes try to ambush them before they reach the water. Males clamber onto the backs of females and hold onto them tightly (a posture known as amplexus), the nuptial pads on their fingers providing extra grip. Over-eager males sometimes grab another male, but the captured male’s croak soon informs them of their mistake. Common toads spawn amongst waterweed. The female releases long strings of triple-stranded eggs, which the male on her back fertilises with sperm. About 600-4000 eggs are laid. These strings become twisted and stretched around waterweed and vegetation so that the eggs settle into two strands. A few days later the adults leave the water. The tadpoles hatch within 10 days and despite being distasteful to most predators, the majority will not reach adulthood. The tadpoles metamorphose into toadlets within 2-3 months - varying according to food availability and water temperature - and leave the water in May. Common toads reach sexual maturity at 4 years of age.

Conservation status
Common toads are not listed by the IUCN. Sadly, in their desperate bid for breeding sites, many toads are run over by traffic - 20 tons are killed annually on British roads alone. Tunnels under the road are an effective way of reducing this toll.

Voice
Only male common toads croak, which can be a useful way of distinguishing males and females, for males will ‘squeak’ if picked up. Larger males have deeper croaks then smaller individuals. This difference in pitch enables toads to assess their chances of success before a fight and so avoid battles that they are likely to lose. The male 'release' call (when another male has mistaken it for a female) is the most often heard call, which is a rough, high-pitched qwark, qwark, qwark. The mating call is rarely heard.

Notes
As well as having an unpleasant taste, common toads also adopt a defence posture when threatened that makes them appear much larger than usual and so deters predators. They do this by stretching out their legs, inflating their lungs with air, and leaning their heads downwards.

Records
The common toad is Europe's largest toad.