Nomenclature

Common name:  Smooth newt
Taxonomy:  Lissotriton vulgaris vulgaris (Linnaeus, 1758)
Previously: Triturus vulgaris vulgaris
Other Names:   Common newt
Madfall ddwr gyffredin, yn gartrefol yn y dwyrain (Welsh)

Introduction

A pair of Smooth newts, female above. © Henk Wallays

Both sexes of Smooth newt grow to between 7 and 11cm, the male being slightly larger than the female. Both male and female have an orange belly (more pale in the female) which is covered in black spots. They have a pale throat which is also spotted. When on land the skin becomes a velvety texture and the male’s crest disappears.

Favoured habitat are ponds (without fish) and ditches with a diversity of aquatic vegetation, not too deep, heavily shaded or fast flowing nor choked with vegetation. They are rarely present in acidic water below pH 6.

The Smooth newt is the most widespread of our three native newts, occurring throughout Britain, but probably declining in rural areas due to habitat deterioration, but this may be partially balanced by their ability to colonise garden ponds.


Identification

Smooth newts can be recognised by their smooth skin and spots on the throat. The dorsal surface colouration variable from light brown to dark brown/black. Larvae that hatch late in the spring may continue to grow in the pond over winter and metamorphose the following spring.


Sexual Dimorphism

The sexes are easiest told apart during the breeding season when the male develops a crest extending from the back of the head to the tail and the orange belly is more intense. The female has a much drabber appearance in the breeding season. The male can be distinguished from the female throughout the year by larger spots on the belly and a swollen cloaca. It is hard to distinguish the sexes of immature smooth newts as all resemble the female in appearance until the males reach sexual maturity.


IDgoofs

On land, Smooth newts are frequently mistaken for a lizard; but can be distinguished by the toes on the front feet newts have 4 toes, lizard 5. Lizards are fast-moving animals, so if you can catch it by hand, then it is probably a newt!

In water, the Smooth newt is most likely to be mistaken for the Palmate newt, and females of the two species can be difficult to distinguish.

Palmate newt - The throat is always white in colour for Smooth newts, rather than pink with a translucent quality for the Palmate. Females are hard to tell apart dark speckling on throat is usually present on the female Smooth newt. Male smooth newt has more developed wavy dorsal crest than palmate in the breeding season.

Great crested newt GCN are much larger than Smooth newts, and have a warty, rather than smooth skin.


Distribution

They are one of the commonest amphibians in Europe. The smooth newt has a wide distribution across Europe, except for southern France, southern Italy, most Mediterranean islands and the Iberian Peninsular. It ranges as far north as northern Scandinavia and is also found in Russia and western Asia.

Across its range it is divided into about seven subspecies. The subspecies occurring in UK is usually found below 500 metres. Widely distributed across England, Scotland and Wales though less frequent in the far north and west. It is native to Guernsey but absent from Jersey and the Isle of Man.

It is found in a wide range of habitats in Surrey and is the most frequently recorded newt in the vice county, though rare in acidic waters, such as heathland ponds.


Habitat

During the breeding season they are found in standing water with plenty of weeds, such as ponds, lake margins and ditches. Outside the breeding season newts come on land and use a variety of habitats such as deciduous woodland, bogs, marshes, wet heath and gardens where they seek damp places such as under logs, stones, leaf litter and in wall crevices.


Activity

During their terrestrial phase they hide by day beneath stones or compost heap, emerging after dusk to feed on invertebrates. They are most easily seen by torchlight while in the pond during the breeding season after dusk on a warm evening.

The animals are most active on rainy nights, or on nights with high humidity, such as before a storm.


Food

Smooth newt predating a tadpole.
© David Jones

The larvae feed on zooplankton.

Adults feed on slugs, worms, insects and other invertebrates during terrestrial phase, projecting their tongue to catch prey.

In the water they feed on aquatic invertebrates such as shrimps, insect larvae, water snails, frog tadpoles and spawn. Aquatic predtation involves grabbing their prey in their minute teeth.


Predators

Fish are the main predator of adult Smooth newts, although they are occasionally taken by adult Great crested newts. Predators of larvae include water beetles, dragonfly nymphs, fish and larger newts.

When threatened, adults remain still, relying upon their camouflage, rather than fleeing. The newt tadpoles tend to stay hidden among the vegetation or detritus at the bottom of the pond.

Grass snake
Grass snake
Mallard
Mallard
Kingfisher © Marek Szczepanek
Kingfisher © Marek Szczepanek

Shelter

They hibernate on land in damp, frost-free shelters, often in holes, under stones and beneath piles of plant debris.


Reproduction

The male tries to attract the female’s attention by sniffing her and swimming in front of her. If she shows interest in him and does not swim off he begins a courtship display which includes wafting glandular secretions towards her by fanning his tail, showing off his breeding colours and crest, and lashing his tail against his body causing a strong current of water. The rate of tail wafting is species specific.

In the final phase of courtship the male deposits a packet of sperm (spermatophore) on the substrate and manipulates the female into position over the spermatophore so that it is taken up into her cloaca and the eggs fertilized. This courtship is likely to be repeated a number of times. Courtship and mating takes place under water while holding their breath. The female will mate with other males so her eggs will have multiple fathers.

Eggs take 10-20 days to reach full term, depending on temperature and quality of the water. The hatchling larva is about 7mm long. They absorb oxygen by external gills and metamorphose into air-breathing juveniles at about 10 weeks. They shed their skin about once a week while growing. They are not sexually mature until about 3 years old and live on average about 6 years.

The female deposits 3 to 7 eggs per day on broad-leaved aquatic plants, each egg individually wrapped in a leaf. If no vegetation is available she may attach eggs to other objects or lay them on the pond bottom as a short string. A female deposits between 200 & 300 eggs in total between March and June.


Tadpoles

The larvae are green/brown with paler underside and small dark spots over the body and tail (spots are more marked in the great crested newt larvae, which also have a spotted tail). The feather gills behind the head will easily distinguish newt tadpoles from frog or toad tadpoles.


Conservation

Numbers are declining across Europe due to loss of ponds in the countryside, pollution, urbanisation and agricultural change. It has declined in rural Britain due to habitat deterioration. Has adapted well to the garden environment and can be helped by having fish free pond. Piles of fallen leaves left in the garden will benefit for terrestrial phase.


Links



Information

Principal Author:Reviewer:Updated:
Sue Cooper Dr Julia Wycherley MBE 10 August 2011