Triturus cristatus (Laurenti 1768)

Elmberg, Johan, 2023, Amphibians and reptiles in North Sweden: distribution, habitat affinities, and abundance (Classes: Amphibia and Reptilia), Zootaxa 5301 (3), pp. 301-335 : 308-309

Great Crested Newt Triturus cristatus (Laurenti 1768)

Distribution ( Figure 3 ). Included records from Artportalen (N=320): due to risk of confusion with the more widespread Lissotriton vulgaris only records documented by a photograph or made by experienced observers have been included.

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 21% of 111 squares in which randomly selected wetlands (<1 hectare, presumed free from predatory fish) were investigated. It is more evenly distributed in Gästrikland than in Hälsingland, and in both provinces there is a clear pattern of more numerous occurrence in areas near the coast. In a similar randomized survey of Medelpad and southern Ångermanland, Olofsson et al. (2008) recorded the species in 3% of 155 randomly selected small wetlands. In coastal southern Medelpad the occurrence is more or less continuous ( Aronsson et al. 2005), as it is in coastal Hälsingland and Gästrikland. In the Middle Boreal there are scattered records north to 63 oN, most of which from east-central Jämtland. A recent photo-documented record in NE Ångermanland suggests that the species may range further north along the coast than currently known. The only record from the Northern Boreal during the study period is a possibly disjunct occurrence in western Jämtland ( Figure 3 ).

Although most known extant breeding sites are in coastal lowland, at least three are at 300–400 m altitude ( Elmberg 1995; Olofsson et al. 2008). An extinct population at Långselberget (Lycksele lappmark (Middle Boreal)) was even higher, at 460 m.

Offshore occurrence is known from only one site in North Sweden (Kråkön, Hälsingland). However, several breeding wetlands on the mainland are very near the sea ( Sterner 2005; Olofsson et al. 2008). This indicates a fair general dispersal capacity, since such wetlands, created by land uplift, are often less than 200 years old.

One local extinction has been documented in the Middle Boreal: the isolated occurrence in Lycksele lappmark, comprising only neotenic individuals, went extinct due to fish introduction in the 1960’s (Långselberget, Stensele; Gislén & Kauri 1959; Dolmen 1978; Elmberg & Ericsson 1983). There is not any indication that the general distribution has changed recently in North Sweden. Instead, the species has previously been much overlooked. It is more widespread, more numerous, and the range more extensive to the northwest than depicted in any previous source (cf. Gislén & Kauri 1959; Elmberg 1995).

Habitat and movements. Most known breeding wetlands in North Sweden are small fishless tarns bordered by coniferous forest (e.g., Sterner 2005; Olofsson et al. 2008). These wetlands are generally oligotrophic and have floating mats of Sphagnum along the shore. However, in coastal areas a fair number of breeding sites of anthropogenic origin are known: farmland ponds, disused fishponds, peat quarries, gravel pits, and golf course ponds. Many of these are meso- to eutrophic and thus more resemble typical breeding habitats in South Sweden. Most known breeding wetlands are permanent, but some are more ephemeral, such as depressions in wet forest and rock pools near the Baltic ( Olofsson et al. 2008).

Observations of moving or migrating individuals are exceedingly few. Their scarcity and location strongly suggest very limited movements away from breeding wetlands and imply a largely aquatic lifestyle in summer, too.

Summer habitat use is almost unknown; a few records of terrestrial adults have been made, mainly under woody debris or in brooks in old spruce-dominated forest near breeding wetlands. During field work at Galtström (Medelpad) August 1 st, we found active adults on land and in a nearby breeding pond, as well as hiding under woody debris in the upper part of the seashore littoral.

Nothing is known about hibernation habits in North Sweden, that is, whether terrestrial or aquatic. However, aquatic hibernation must have been the rule in the extinct neotenic population at Stensele in Lycksele lappmark ( Dolmen 1978).

Abundance estimates and trends. There are not any data about local abundance. Given the patchy distribution, suggesting abundance estimates for larger areas is unwise. 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 several hundred breeding wetlands in this region.

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

Figures

FIGURE 3. Distribution of Triturus cristatus in North Sweden.Areas colored darker denote more continuous range, and lighter color areas where records are more scattered. Likely disjunct occurrences are shown by filled circles and an offshore record by a triangle. A question mark shows area where presence is likely but has not been documented.