Lissotriton vulgaris (Linneaus 1758)

Elmberg, Johan, 2023, Amphibians and reptiles in North Sweden: distribution, habitat affinities, and abundance (Classes: Amphibia and Reptilia), Zootaxa 5301 (3), pp. 301-335 : 306-308

Smooth Newt Lissotriton vulgaris (Linneaus 1758)

Distribution ( Figure 2 ). Included records from Artportalen: all reports (N=670), as there is no confusion species except the much rarer Triturus cristatus .

Widely distributed in the Southern Boreal; in a regular sampling grid covering the entire provinces of Gästrikland and Hälsingland, Sterner (2005) found the species in 42% of 111 squares in which randomly selected wetlands (<1 hectare, presumed free from predatory fish) were investigated. In both these provinces there is a pattern of more widespread occurrence in coastal areas than farther inland. In a similar randomized survey of Medelpad and southern Ångermanland, Olofsson et al. (2008) recorded the species in 23% of 155 randomly selected small wetlands. In the southern Middle Boreal this species is seemingly more patchily distributed, especially in the northern parts of the range. There are only two known extant occurrences in the Northern Boreal: Akkan and Abborrberg (4 kms apart in Stensele parish) in Lycksele lappmark ( Persbo et al. 2006, Anders Forsgren pers. comm.).

Interestingly , three of the northernmost occurrences are also the highest known from North Sweden (and in Sweden overall): Akkan and Aborrberg are both 520 m above sea level, and Jägarliden at 340 m (all in Lycksele lappmark; Persbo et al. 2006).

Offshore occurrence is known from two islands in Medelpad (Brämön and Alnön; Elmberg & Ericsson 1983) and one in Hälsingland (Jättholmarna), indicating a fair dispersal capacity over brackish water. In coastal areas where the species occurs, many mainland records are very close to the sea ( Elmberg 1995; Sterner 2005; Persbo et al. 2006; Olofsson et al. 2008). This pattern indicates a good general dispersal capacity, since such wetlands created by land uplift, are often less than 200 years old.

There are not any data to gauge large-scale changes in distribution during the last 50 years, but local extinctions due to fish introduction have been documented ( Dolmen 1978; Elmberg & Ericsson 1983; Persbo et al. 2006). One of these populations comprised neotenic individuals only (Långselberget, 460 m altitude, Stensele, Lycksele lappmark; Gislén & Kauri 1959; Dolmen 1978; Elmberg & Ericsson 1983). The northern distribution limit presented here runs farther north than in Gislén & Kauri (1959). This discrepancy is, however, not due to a range expansion but rather because the species has been overlooked before.

Habitat and movements. Breeding habitats include tarns and small lakes in forested areas, as well as more or less permanent man-made wetlands (e.g., ponds, pasture pools, gravel pits). Tarns and lakes are usually oligoto mesotrophic, bordered either by floating Sphagnum mats or by moderately dense stands of aquatic grasses ( Phragmites australis , Phalaris arundinacea ) or sedges ( Carex spp .) ( Figure 11 ). The majority of known breeding wetlands are fishless (cf. Elmberg & Ericsson 1983; Sterner 2005; Persbo et al. 2006) and lack connection to other wetlands by streams. Several of the occurrences away from the more continuous range are isolated, either high on forested hills or in large peat bog complexes. Breeding sites are usually permanent wetlands, but the species has been recorded in ephemeral rock pools on the Baltic coast ( Elmberg & Ericsson 1983; Aronsson et al. 2005; Figure 12 ).

Summer habits and habitats are little known, as very few observations are made away from the breeding wetlands. Adults can be seen in the latter long into June, sometimes to mid-July. It is thus possible that many remain aquatic for a large part of the summer. During field work at Galtström (Medelpad) August 1 st we found active adults on land as well as in a nearby breeding pond. Terrestrial habits in North Sweden are little known; most records on land have been made under logs or woody debris in damp spruce-dominated forest close to breeding sites. Terrestrial summer records have also been made under flat sheltering objects near man-made wetlands.

Hibernation habitats and habits in North Sweden have not been documented; it is not even known whether terrestrial or aquatic hibernation is the rule. However, aquatic hibernation was the only option in the neotenic population at Stensele in Lycksele lappmark, now extinct ( Dolmen 1978).

Very little is known about seasonal movements. The almost total lack of observations of adults moving to or from breeding wetlands strongly suggests they spend much of their life in the latter or their close proximity.

Abundance estimates and trends. There are very little data on local abundance, and no indication that any breeding wetland holds more than 200 reproducing adults (e.g., Dolmen 1978; Elmberg & Ericsson 1983; Sterner 2005; Persbo et al. 2006; Olofsson et al. 2008). Given the patchy distribution, it is unwise to suggest abundance estimates for larger areas. However, the surveys by Sterner (2005) and Olofsson et al. (2008), which covered a mere fraction of the suitable wetlands in the Southern Boreal, suggest there must be thousands of breeding wetlands in this region.

There are no indications of changes in abundance over the last 50 years, apart from local extinctions.

Figures

FIGURE 2. Distribution of Lissotriton vulgaris in North Sweden. Known continuous range is colored. Possibly disjunct occurrences are denoted by filled circles and offshore records by triangles.

FIGURE 11. Mesotrophic lakes with extensive beds of grasses and sedges provide breeding habitat for Rana temporaria, R. arvalis, and Bufo bufo. If fishless, also Lissotriton vulgaris is likely to occur in lakes of this type. Spring aspect from Öster- Skivsjön, Västerbotten, Middle Boreal region. Photo: Johan Elmberg.

FIGURE 12. Ongoing post-glacial land uplift creates open habitats along the Baltic coast of North Sweden. Rock pools (foreground) serve as breeding sites for Rana temporaria and Bufo bufo, occasionally also for Lissotriton vulgaris. Brushy areas along the forest edge (background) are typical summer habitat for Zootoca vivipara and Vipera berus. Tjäruskär, Ångermanland, Middle Boreal region. Photo: Johan Elmberg.