Description

Smooth newts (Lissotriton vulgaris) have a grey-, loamy- olive colored dorsum and sides. The belly is yellow - orange with large black spots. Between the sides and belly runs a long, light (or silvery) colored stripe. Smooth newts attain sizes up to 11 cm is one of the smallest newts in the Netherlands (the palmate newt - Lissotriton helveticus, being the smallest).

During the mating season (spring, aquatic phase) males develop a high dorsal crest. Before and after breeding season the animals adopt a terrestrial lifestyle and both males and females have a grainy skin and a brown base color. Larvae are very difficult to distinguish from the larvae of the palmate newt.

 

Distribution and Life History

The smooth newt is the most common newt in the Netherlands. The species does not demand high requirements of both its terrestrial- and aquatic habitat. Aquatic habitat includes a wide variety of canals, ponds and other bodies of water as long as the water flow is not too strong and their are not to many predators (mainly fish). The species occurs in urban habitats (like gardens), small scale (agricultural) landscape, nature areas, wooded areas and heathlands. 

Breeding waters are preferably not to deep with no to little waterflow. Ideally waters or not to big with plenty of sun exposure and support at least some (under-) water vegetation. Mating season starts, depending on prevailing weather conditions, from early March until June (with a peak during April and May). Females deposit 100-350 eggs in a season. Each egg is individually deposited and folded in a leave of underwater vegetation.

 

Protection

Smooth newts are listed as not threatened in the national Red List (Staatscourant, 2009 cf. van Delft et al.,2007). The species is included, as are all Dutch amphibians, in the national law which protects native species (Flora and Fauna wet). Smooth newts are included as a protected species in appendix three of the Bern Convention.

 

Monitoring

During mating season smooth newts can be observed in the water. July is the best month to search for larvae, which does require sampling the water with a dipping net. Smooth newt and palmate newt larvae are indistinguishable from each other. Outside of the range of the palmate newt searching for larvae make a very useful survey method. Where the ranges of both species overlap eggs and larvae are less useful and need to be combined with surveys targeted at adult animals. 

  • counting adult animals in the evening (March until May)
  • searching for larvae (June until August)
  • searching for eggs (April until May)
  • surveys often require a dipping net