Common toad  (Bufo bufo)

Protected in Britain under Schedule 5 of the Wildlife and Countryside Act (1981) with respect to sale only. Listed under Annex III of the Bern Convention and Classified as a Species of Conservation Concern under the UK Biodiversity Action Plan (UK BAP), but not a priority species (3).

The common toad is surrounded by a wealth of folklore and superstition (4). It can alter the tone of its skin to suit its surroundings; the upper surface may be brown, greenish or grey, and occasionally features dark markings. Females are often more reddish or brown than males. The underside is typically white or grey, and the eye, which has a horizontal pupil, is copper in colour. The most obvious feature that distinguishes this species from frogs is its warty skin; these dark warts secrete powerful toxins when the toad is harassed (2), and potential predators soon learn to avoid toads (5).

This species has a very wide British distribution, and is uncommon only in north Scotland. Elsewhere, it has a broad range, which extends from Scandinavia in the north to northwest Africa, and from Portugal extending as far east as Lake Baikal in Siberia. It is however, absent from many islands, including Crete, Malta, Corsica, Sardinia, the Balearics and Ireland (2).

Common toads occur in a broad variety of habitats, including gardens. Large water bodies are required for good populations, and optimal habitats seem to be woodland, scrub and rough grasslands. Breeding ponds containing fish appear to be preferred; the tadpoles are unpalatable and are protected from fish predation (2).

Common toads are largely nocturnal. They are found in ponds only in the breeding season; during the rest of the year they can be found far from water bodies (5). They have a broad diet, feeding on a huge range of prey small enough to swallow, including insects, spiders, earwigs, earthworms, snails and slugs; they have even been observed eating young toads (2). They feed only on land and use a 'sit-and-wait' style of hunting (6). Toads are usually welcomed by gardeners, thanks to their voracious appetites and penchant for garden pests (4).

The life cycle is similar to that of the common frog (Rana temporaria). Common toads begin to migrate to breeding ponds in autumn. The onset of cold weather stimulates hibernation, which takes place en route in abandoned rodent burrows or in leaf litter (2). Migration then recommences in spring.

Breeding activity, which occurs between March and June (6), is often very frenzied in this species, with much competition amongst males over access to females. Males grasp females tightly prior to spawning, and there is aggressive activity amongst males who try to 'take-over' females. 'Mating-balls' may often arise, when as many as 10 males jostle for access to a single female; the female occasionally drowns or is crushed as a result (2). Successful pairs will spawn; females release a double-string of eggs, which the male fertilises by releasing his sperm simultaneously. The pair moves around whilst spawning, so that the jelly-coated strings of eggs become wrapped around vegetation. One female may produce up to 5,000 eggs, although the usual number is around 1,500 (2). The black tadpoles move away from the spawning areas a few days after hatching. The tadpoles feed on microorganisms and usually gather in groups, which, in addition to the presence of skin toxins, probably protects them further against predation. Despite this, however, they frequently become prey for diving beetles and other species that have piercing mouthparts, and so can avoid the toxins in the skin (2). It takes 8-12 weeks for tadpoles to develop, after metamorphosis the tiny toadlets occasionally emerge en masse. Sexual maturity is reached after 2-3 years (2). Common toads can live for a very long time; some captive individuals have reached 50 years of age (5).

Although this species is common and widespread in Britain, it is likely that habitat loss, particularly the drainage of wetlands, has affected populations (6).

It is illegal to sell common toads under the Wildlife and Countryside Act, 1981 (3).

For more on this species and other amphibians and reptiles of the UK see The Herpetological Conservation Trust:
http://www.hcontrst.f9.co.uk
For more on amphibians of the world see Amphibia Web:
http://elib.cs.berkeley.edu/aw/search/index.html

• Hibernation: a winter survival strategy characteristic of some mammals in which an animal's metabolic rate slows down and a state of deep sleep is attained. Whilst hibernating, animals survive on stored reserves of fat that they have accumulated in summer. In insects, the correct term for hibernation is 'diapause', a temporary pause in development and growth. Any stage of the lifecycle (eggs, larvae, pupae or adults) may enter diapause, which is typically associated with winter.
• Metamorphosis: an abrupt physical change from the larval to the adult form.
• Nocturnal: active at night.

1. National Biodiversity Network Species Dictionary (January 2003): http://www.nhm.ac.uk/nbn/
2. Beebee, T & Griffiths, R. (2000) The New Naturalist: Amphibians and reptiles- a natural history of the British herpetofauna. Harper Collins Publishers, London.
3. The Environment Agency (1998) 'Look-up' chart of species and their legal status. Species and Habitats Handbook. The Environment Agency, Bristol.
4. Buczacki, S. (2002) Fauna Britannica. Hamlyn, London.
5. The Herpetological Conservation Trust- common toad fact-sheet (January 2003): http://www.hcontrst.f9.co.uk
6. Amphibia Web (January 2003): http://elib.cs.berkeley.edu/aw/search/index.html