The smooth newt is probably the most common species of newt in Britain, though not necessarily in Somerset where the palmate newt is more common in some regions. Smooth newts are easily distinguished from great crested newts by their smaller size and their colour. However they are not always quite so easy to distinguish from palmate newts, which to the unpractised eye they closely resemble, perhaps explaining why palmate newts were not described as a species until thirty years later than the smooth newt.
Smooth newts average about 10 cm in length; however their appearance differs considerably depending on whether individuals are in an ‘aquatic phase’ or a ‘terrestrial phase’.
During their aquatic phase the skin is, as their name suggests, smooth. The ground colour varies from shades of olive green to pale brown. In the case of males, the ground colour is overlaid with large dark spots, and during the breeding season they are adorned with an unbroken crest running from the top of the head to the tip of the tail. The underside is strikingly coloured in orange or red, similarly overlaid with heavy dark spots, and the lower edge of the tail is often blue. Curiously, William Baker writing about newts in Somerset in 1851, erroneously considered that the smooth newt may be a complex of two types: the smooth newt and the fringe-footed smooth newt, distinct from the palmate of which he was also aware. When in peak breeding condition male smooth newts can develop flaps of skin along the fringes of the toes of the hind feet which may have led to this confusion, but their feet are never webbed, as in the palmate newt.
Females share the dorsal ground colour but are not as heavily spotted as the males, instead having a fine scattering of dark spots which sometimes coalesce into fine lines running down the back and either side of the tail. The underside is usually paler than that of the male, being some shade of yellow.
During their terrestrial phase the texture of the skin changes, taking on a rather velvety appearance, while the ground colour becomes paler adopting a shade of yellow ochre or buff brown. The large dorsal spots, characteristic of the breeding males, fade at this time leaving both sexes with a rather uniform appearance.
The throat is often used to try to distinguish female smooth newts from palmate newts. The throat of a smooth newt is white, usually overlaid with fine ‘pepperpot’ spots, while that of a palmate newt is almost translucent pink and lacks any spots. Furthermore, the two species can be differentiated by the colour of a small pair of tubercles on the soles of the back feet, one positioned at the base of the inside toe, and another on the outside edge of the sole. In smooth newts these are brown, whilst in palmate newts they are white.
Smooth newts are undemanding in their choice of breeding ponds, using the entire range from small ornamental fish ponds to large lakes or slow moving canals and show little fidelity to any particular pond.
While newts are primarily nocturnal or crepuscular, the smooth newt appears to be the most diurnal of the three species, often being active close to the surface of the water in bright sunshine, while the other species may be hidden away at depth.
Verifying records for smooth newts and palmate newts can be a frustrating task. The similarities between the species mean that only records collected by specialists tend to specify to which the record refers. Clearly, unspecific records are not useful for determining the distribution of either species and have therefore been omitted from the maps, so both species are undoubtedly considerably more abundant than the maps would suggest.
Smooth newts are common and widespread across most of Somerset and the unitary authorities, being found in a wide range of habitats including urban and suburban gardens. Across much of the county the species co-exists with palmate newts, although there are regions where one or other may be absent, and in those regions where both are found there are often differences between the proportions in which each is found.
It is frequently remarked that palmate newts are better adapted to conditions at altitude than smooth newts, and broadly speaking this might explain discrepancies between the distributions of the two species in Somerset. However, the picture is a little more nuanced as neither species is particularly specialised, and while palmate newts tend to predominate at altitude they can also be found in the lowlands, while the opposite is true for smooth newts, which tend to predominate at low altitude but can also be found in the hills.
Baker and Charbonnier in the nineteenth-century both simply declared the smooth newt to be very common in the county, while Mary Wood, writing in 2002, found smooth newts to be more common than palmates in the unitary authorities, with records for both species concentrated around the Bristol area, and fewest in BANES.
Smooth newts are the most common species of newt on the lowlands of the levels and moors, where palmate newts are comparatively scarce. Conversely, smooth newts are less common than palmate newts in the dew ponds on the Mendip Hills and are rare on Exmoor and the high ground of the far west of the county where, in some areas, conditions are very acidic. However, several reliable records exist for smooth newts in the vicinity of Minehead and Selworthy, so the species may be more widespread in the Exmoor region than currently recognised.
Both species are plentiful across the relatively high ground of the mid Somerset hills and the Yeovil scarplands as well as the low lying valleys such as Vale of Taunton Deane and the Chew Valley although further survey effort is required to determine which species predominates in which of those areas.
Beyond Somerset the smooth newt has the widest distribution of all three British newts. Within Britain it is widespread across England, Wales, and Scotland, where in many places it is the most abundant species, and it is the only species of newt found in Ireland. On the continent it is absent from the Iberian Peninsula and western France, but widespread elsewhere, reaching as far north as Central Scandinavia and as far south as Greece and Western Turkey. It can be found throughout Eastern Europe extending east as far as central Siberia.