Common toads (c) Tom Aspinall
The common toad (Bufo bufo) is widespread throughout the UK, including in the Community Science project area, although it is absent from the very highest ground.
Adults usually emerge in spring and migrate to ancestral breeding ponds on mild, damp evenings, using the same route every year. They prefer deep breeding ponds that do not dry out. Males wait near the pond and ‘piggy back’ on females making their way to the pond. Females lay eggs in strings of spawn that are fertilised by males as the female lays them and are then wrapped around vegetation. Strings of spawn can contain between 3 and 6 thousand eggs.
After mating, adults leave the pond and spend the summer and autumn in woodlands, scrub and rough grasslands, hunting for slugs, spiders and insects, preparing for winter. Larger toads can also take small vertebrates such as slow worms, small grass snakes and harvest mice. They are active at night and shelter under rocks and logs during the day.
Depending on weather conditions, tadpoles hatch two to four weeks after the eggs are laid. After about 16 weeks tadpoles grow legs and when they have absorbed their tails they also leave the pond, usually after it has rained. They also spend the autumn hunting in preparation for winter. Like other amphibians, toads hibernate over winter in dry frost free places in woodland, disused mammal burrows or in gaps under manmade objects such as compost heaps, sheds or log piles. In the wild, toads can live for up to 10 or 12 years.
Common toads have glands in their skin that produce toxins that are distasteful and deter most predators. However, some predators such as grass snakes are not affected by this and others such as otters, stoats and crows do take the toad but avoid or peel off the skin. Toad tadpoles also contain these skin chemicals and are therefore less likely to be eaten by fish so toads are often found in fishing ponds and other water bodies with fish populations.
Common toads are in decline in the UK. Threats are likely to include agricultural intensification, habitat fragmentation, habitat loss, chytrid disease, urbanisation as well as more road deaths during migration as traffic increases.
In Britain, the common toad is protected by law from sale and trade and is recognised in law as a species of principal importance for the purpose of conserving biodiversity.
- Males can grow up to about 8cm long whereas females can reach up to about 9cm. Occasionally individuals may be slightly larger than this.
- Colour varies from dark brown or olive-brown to light sandy green. Some individuals are very dark and others brick-red.
- They have warty skin that looks relatively dry.
- Eyes are copper/golden coloured and have two distinct lumps behind them.
- Toads tend to crawl rather than jump.
- Toads lay their spawn in long strings, not clumps.
The main confusion species is the common frog (Rana temporaria). Frogs are also variable in colour but have moist and smooth-looking skin, and two raised ridges along their back. Frogs jump rather than crawl, and lay their spawn in clumps.
In the UK the only other native toad species is the natterjack (Bufo calamita) which has a distinctive pale stripe along its back. The natterjack toad is restricted to coastal dune systems and sandy heaths, only occurring in small numbers on about 60 sites.
There are a handful of other non-native frogs and toads which are present in the UK, but are not widespread.
Why we’re interested
Changing climatic conditions may favour common toads in the UK and so they are expected to expand their distribution, including gaining territory in the Peak District area.
Records submitted to their survey will help to track changes in the distribution of the common toad in the Peak District and surrounding areas and help to determine whether this relates to changing climatic conditions.
Temperature also has an effect on the timing of events (phenology) of common toads, such as spring migration and breeding. Records collected in this survey will also be used to track whether the timing of events is changing and whether this is linked to changes in climatic conditions.
Further information about toads and climate can be found in 'Climate change modelling of English amphibians and reptiles: Report to Amphibian and Reptile Conservation Trust (ARC-Trust)'.