Smooth newt

Smooth newt
Smooth newt
Triturus (Lissotriton) vulgaris

As the only Irish amphibian that possess a tail, smooth newts are readily identifiable. Male and female newts are also clearly distinguishable. Both sexes grow to approximately 10cm. Males are a brown/green colour on the upper body, with pale flanks and an orange belly. Females can vary in colour from pale to dark olive/brown with a paler belly and less pronounced spots. In the breeding season, the males develop a toothed crest from head to tail and bright blue and orange colour along the lower edge of the tail. When newts leave the water the skin becomes dull and ‘velvety’ and males begin to look more similar to females. Immature newts also resemble small females. Smooth newt larvae are predatory and resemble miniature pale brown adults, but with external gills and a more prominent tail.

Life-Cycle and Behaviour: 

Although a small proportion of newts overwinter in ponds, the majority hibernate on land and return to their breeding ponds in late-January/early-February. They mate and lay eggs (wrapping each of them in the leaves of aquatic plants) during April and May and the adults leave the ponds in June to spend the rest of the year in terrestrial habitats. Their larvae develop in the ponds until approximately September, when they begin to emerge. Adult smooth newts spend the majority of their lives on land, during which time they are relatively inactive. They spend much of this time in refuges, emerging to feed at night, under relatively warm, damp conditions. They generally prey on small, soft-bodied invertebrates.

Habitat Preferences: 

Smooth newts tend to reach highest densities in fish-free ponds and ditches with a diversity of submerged and emergent vegetation. Deep, flowing or heavily shaded waterbodies are less favoured, but smooth newts can exploit a range of wetland features. They can also be found within a range of terrestrial habitat types in the vicinity of ponds, showing preferences for damp, un-grazed grassland, woodland and scrub.

Survey Techniques: 

Surveys for smooth newts will be required when waterbodies potentially inhabited by breeding newts are located within 250m of the proposed working area. If remote hydrological or pollution effects from greater than 250m distance from the waterbody thesurvey ‘corridor ’ should be extended, as appropriate.

In order to confirm the presence or absence of newts reliably, it is necessary to employ a combination of survey techniques and to re-visit the waterbodies in question at intervals over the period during which the number of breeding adults reaches a peak (late-March to late-May). Waterbodies should be visited on up to four occasions during this time, ideally at roughly two-week intervals spread throughout the period, but with at least two visits in the early-April to early-May ‘window’. On each occasion, a combination of techniques should be used, as determined by the conditions of the waterbody: torchlight inspections, egg searches, funnel trapping and dip-netting. Torchlight inspections represent the most reliable and efficient technique in situations where visibility is good, and this combined with searching for eggs represents the preferred option.

These techniques should be supplemented by trapping and netting as appropriate, especially in situations where using a torch is compromised by water turbidity, access constraints and rank bank-side vegetation. In order to reliably infer the absence of newts from an otherwise suitable waterbody, at least three techniques applied over four visits are necessary. It is imperative that biosecurity measures are taken when carrying out amphibian surveys in order to avoid the incidental spread of vector borne diseases (such as crayfish plague) between waterbodies. This includes cleaning, appropriate disinfection and thorough drying of all equipment between surveys undertaken on different waterbodies and watercourses.

Optimum Survey Period: 

Surveys for smooth newts are seasonally constrained within specific periods. To survey for breeding adults within waterbodies, up to four visits should be undertaken, spread at intervals between late-March and late-May.

Mitigation, compensation and enhancement: 

Where capturing and relocating newt populations is necessary, breeding ponds should be encircled by drift fencing and pitfall traps prior to the spring migration period, when newts can be intercepted on their journey to breed. Netting and draining-down of ponds should also take place to remove as many of the remainder as possible. Where large populations of newts are found close to the proposed works, amphibian-proof fencing can be helpful in protecting the resident animals. Permanent fencing can also be used to guide newts to purpose-built tunnels and other safe crossing structures, although their effectiveness for newts remains largely unknown.