Habits
The animal comes out of hibernation around the beginning of April, to re-enter water,
which is often brackish, and frequently in dune slacks. Breeding takes place from late
March through and into summer, the female laying a band of rather few eggs in one or
two rows, twisted round reeds and water plants, and deposited at night over a few hours.
The tadpoles are the smallest of European anurans, often with paler spots, a pale back
stripe and a mouth only half as wide as the Common Toad's. The toadlets have
metamorphosed at about 6 to 7 weeks, when only a third of an inch long.
Peculiarly, the Natterjack gait is a running motion similar to a mouse, stopping every
30cm or so for a brief rest. It is able to jump, though rather clumsily and only for short
distances. It is an excellent climber and may be found several feet above surrounding
ground level.
Food is of imago and larval arthropods, caught at night. It is nocturnal, usually passing
the day buried in sand, although it may be encountered along dune ridges. Hibernation is
usually October to February. Unusually among amphibians, the Natterjack is able to
withstand long periods of drought. This adaptation to drought may be associated with an
ability to withstand higher saline levels. As a protection against predators, it secretes a
whitish substance from its skin, carrying a smell reminiscent of burnt sulphur and india
rubber.
Carnivorous beetles will prey on tadpoles and newly developed toadlets, newts will take
tadpoles and the tadpoles themselves are often cannibalistic in the absence of suitable
food. Birds such as Heron, Wigeon and Black-headed gull and mammals such as rats and
foxes may actively seek the adults for food, trying to skin the carcass before devouring it
in order to avoid the poisons present in the skin (the venesio-horrendi of Linne).
Bufotoxin, bufotalin and bufotenin have been extracted from Common Toad exudates.
Habitat and distribution
The species is local in distribution and because of its burrowing habits it tends to live in
sand dunes, dune slacks, or on sandy heaths, usually in coastal areas, not going inland.
Malcolm Smith (1969) says that in the British Isles the Natterjack is only found at around
sea level. He says that occasionally whole colonies will migrate for no understood
reason. The Natterjack is not so faithful to one pond for breeding as the Common Toad,
and may even deposit spawn into puddles or ditches that can diy up before the tadpoles'
metamorphosis, causing their death.
Deryk Fraser (1983) says that there have been reports of B. calamita from boggy ground
in Cambridgeshire, and from sandstone areas of the Furness region of Lancashire. He
also says it was formerly known in a band from Dorset, Hampshire and Surrey to East
Anglia, though it is now found in small numbers in Hampshire and a few coastal areas of
Norfolk and Lincolnshire, with other populations along the coast from the Dee to the
Solway, also including the Scottish shore. Malcolm Smith (1969) said that it was present
in the sandy areas of Woking. The Lincolnshire and South Humberside Trust state that
this animal is to be found on their Saltfleet-by-Theddlethorpe reserve, on the coast just
north of Skegness, in its last area in Lincolnshire. Ros Evans says it is to be found at
N.C.C. Studland Heath reserve on the Isle of Purbeck in Dorset.
Reasons for decline
As noted the species prefers loose sandy soil of dunes and heaths, and heathland is one of
the fastest decreasing habitats in this country. It appears to require pools with a high pH
- a rare occurrence on heathland and becoming even scarcer. Small ponds have a
Essex Field Club Newsletter No. 21, May 1997