The Smooth newt (Lissotriton vulgaris) is the most common newt found throughout the UK and they are popularly known as the Common newt. In the spring and summer months they are a frequent visitor to garden ponds and slow flowing streams and natural pools. They spend the autumn and winter on land under rocks, logs and leaf litter.
Adult smooth newts measure approximately 10cm from head to tail. When seen underwater in spring and summer, the sexes are usually easily separated. The males develop a ridged crest along the centre of his back and tail. He also displays a vivid orange spotted with black along his underside and running into his tail. The main body is a dark brown colouring mottled with darker spots. There is a blue line seperating the orange and brown along his tail. The female is much more nondescript. She is a lighter brown than the males and lacks all of the vivid colouration. There is a small patch of dull orange along her underside and she has slight darker brown mottling. This mottling runs under her chin, which is one of the distinguishing factors between female smooth newts and female palmate newts.
Throughout the autumn and spring when they are terrestrial there are less differences between the sexes. The crest and bright colours of the male shrink and fade until he has only slight orange colouring underneath and just a dark dorsal stripe. The brown colouring of both sexes can vary throughout their terrestrial phase and their skin is visibly drier and appears velvety.
The diet of terrestrial smooth newts mainly consists of worms, slugs, caterpillars and other small invertebrates. Whilst in their aquatic phase the newts consume aquatic invertebrates, tadpoles and occasionally flying insects that fall into the water.
In March to April adult newts migrate to their breeding ponds. Once there the males begin their courtship displays, flicking their vibrant tails and maintaining a sideways posture towards any potential mates. Once the female has selected the male, he drops a spermatophore on the pond bed and she picks it up using her cloaca. Several days later the female begins to lay oval, cream coloured eggs measuring 3-5mm surrounded by a layer of clear jelly. The eggs are laid on the underside of the leaves of aquatic vegetation. She wraps the leaves around the eggs to offer them more protection from predation. From 5 to 15 eggs are laid daily, usually on seperate leaves.
The eggs can take from 14-24 days to hatch with the newly hatched larvae being sustained on the remnants of their eggsacks for the first few days. After this the larvae are carniverous, feeding on small aquatic invertebrates. The newt tadpoles have elongated bodies and external feathery gills. After several weeks the newt tadpoles develop front legs and shortly after, back legs. At this time the tadpole begins to absorb their external gills and starts to rely on breathing air from the surface. The young newts, known as efts then emerge from the water and begin their terrestrial lives. It takes 3 years for efts to grow into adults and to be sexually mature.
Threats and Impact
In recent years the smooth newts populations have remained rather steady, this could be in part due to their ability to quickly colonise new pools and ponds. The main threat to this species in the future is habitat fragmentation and destruction.
The best way to help and encourage this species is the creation of shallow ponds and waterside habitats suitable for terrestrial newts such as log piles and slabs to hide underneath.