Common frogs hibernate through the winter, either at the bottom of ponds (breathing through their skin) or on land under refuges such as compost heaps (5). During the rest of the year they hunt on land on damp nights; they feed on snails, slugs, worms and a range of insects (5). In spring, males arrive at breeding areas before females, and it is thought that individuals return to their natal ponds by following scents (5). There is typically heavy competition amongst males for females, involving much croaking and wrestling. Males grab a female and remain clasped to her body for days or weeks before spawning takes place. All of the frogs in a pond tend to spawn roughly within a few days of each other. The female releases 1000 to 2000 eggs, the male then releases sperm. The eggs are coated in jelly, and are popularly known as 'frogspawn'. After 10-14 days, the tadpoles hatch, becoming free-swimming a few days later, and undergoing metamorphosis into adults 10-15 weeks after hatching. Tadpoles are vulnerable to predation by a range of aquatic creatures, including water beetles, newts and fish (5).