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
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.
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.
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.