Common Frog

Amphibians share an ancient Devonian ancestry with the lobe-finned fish and lungfish, evolving from an early tetrapod group, the Temnospondyli. Later along this lineage the mammals evolved, followed by the reptiles. The surviving amphibian groups are the frogs, toads, salamanders, newts, caecilians, and sirens. Owing to severe degradation of moist and aqueous habitats around the world a large number of amphibian species are endangered, 13% of known species (1393 species), with a further 24% (1567 species) seriously depleted. There are 8 species of amphibian in the UK and Crown Dependencies; Common Toad, Natterjack Toad (coastal sites only), Common Frog, Pool Frog (East Anglia and the Fens), Agile Frog (Jersey only), Smooth Newt, Palmate Newt, and Great Crested Newt. The Natterjack Toad and Great Crested Newt are legally protected.

The amphibian life cycle begins as an egg in jelly, laid in water, which then hatches into a tadpole. It has gills to breathe underwater, and a tail to propel itself. Then legs grow, and the tail and gills are lost as lungs develop to breathe in the atmosphere. It leaves the water when the legs are fully grown.

Amphibians are unable to control their body temperature internally, so their degree of activity depends on the environmental temperature. During the Winter they are largely dormant, and seek refuge underground or in sheltered places, to emerge in Spring according to the prevailing weather conditions and latitude. In Sussex Common Frogs appear from January, while Common Toads and the newts appear from March, all making for ponds to breed.

British Amphibian Identification and Location

Before one can discover amphibians one must get to know their environment, and this means spending time in their habitat to get to know its characteristics; its sights, sounds, odours, tastes, and textures, and how these change with the weather and seasons, as well as with human interference. Visit the habitat in all weathers and at all times of the year, and look, listen, smell, taste, and touch all parts of it (tasting only what is safe). When you know the habitat intimately, you will be able to detect when it has changed because of the presence of an amphibian.

If you know the amphibian’s lifestyle, especially when it is likely to be active (hunting, seeking a mate, courtship, escaping from a predator, etc.), you will sense its presence and why it is there. Particularly, you must look, listen and smell, and respond accordingly. Be silent, but if this is impossible then keep stopping to discern if what you have detected is reacting to your movement and its ceasing. Once you know what sensory differences are expected from a certain amphibian’s presence you will begin to find it easier to track it down.

Wind, rain, sunlight, snow, ice, and other meteorological elements all affect a habitat, and you must know how and with what consequences. Similarly, you must judge how wildlife will react to weather if you want to find it. Finding an amphibian that will be sheltering in water or damp cover is very difficult because it knows the nooks and crannies better than you do. ‘Think animal’ all the time. Whatever the weather, amphibians still have to feed, and by thinking animal you can work out how and possibly where.

An amphibian’s life starts in water, but adult amphibians spend most of their time on land, generally leaving few traces. They swallow their prey whole so don’t leave food remains. In order to keep moist they frequent wet or shady conditions, hiding under stones, logs or in crevices. Frogs and toads will bed down in the mud at the bottom of a pond; newts will go under vegetation or logs. Warm evenings after rain are a good time to observe amphibians, as they are most active after the heat of the day is over. At night a torch will pick them out at pond edges. Frogs have fully webbed hind feet so are good swimmers. All newt species lay eggs singly, frogs and toads in clumps.