Zootoca vivipara (Jacquin 1787)

Elmberg, Johan, 2023, Amphibians and reptiles in North Sweden: distribution, habitat affinities, and abundance (Classes: Amphibia and Reptilia), Zootaxa 5301 (3), pp. 301-335 : 316

Viviparous Lizard Zootoca vivipara (Jacquin 1787)

Distribution ( Figure 7 ). Included records from Artportalen (N=775): all reports have been included, as there are not any confusion species.

Widespread and common in the Southern, Middle, and Northern Boreal. Widespread but scarce in the Subalpine zone. Locally occurring above treeline in the Low-Alpine zone in favorable microclimates.

As expected, the highest known occurrences in the Scandic Mountain range are gradually lower towards the north: 1000–1050 m altitude in Härjedalen (Sånfjället and Flatruet), 740 m in Pite lappmark (west of Vuoggatjålme), and 690 m in Lule lappmark (Vastenjaure).

There is just one record from a truly far offshore island (Stora Fjäderägg, Västerbotten; Figure 7 ; Elmberg 1995). Although common in seashore habitats on the mainland along the entire Baltic coast of North Sweden, there are surprisingly few records even from nearshore islands. An exception may be the archipelago in southern Norrbotten, where the species occurs on some outer islands (e.g., Stor-Räbben and Vargön, green offshore area in Figure 7 ; Stefan Andersson, personal communication). For North Sweden as a whole, this indicates a limited dispersal capacity over brackish water.

There are no indications of changes in distribution over the last 50 years.

Habitat and movements. Found in almost any habitat offering a combination of basking sites and protective low vegetation. Favored natural habitats are forest edges and clearings, stony slopes, rock outcrops, sandy areas, and shores of lakes, rivers and the sea ( Figures 12 , 14 ). It often occurs among Juniperus communis , Calluna vulgaris , Empetrum nigrum and other plants typical of dry sun-exposed conditions. Closed forest, tall grass, and wet habitats are avoided. Anthropogenic habitats are widely used, for example clearings under powerlines, clear-cuts, edges of fields and meadows, stone walls, cairns, and roadsides ( Figures 13 , 19 ).

There have not been any dedicated studies of this species in North Sweden. As far as known, it spends the entire annual activity period in the habitats mentioned above. Daily and annual movements are not known but appear very limited. Subterranean hibernation sites are found in or close to the summer habitat, usually in south-facing situations.

Abundance estimates and trends. There are not any published abundance data, but estimates based on extensive field work in the Umeå area (Västerbotten) 1975–1994 run in the neighborhood of> 500 adults /km 2 in representative landscapes near the coast (Elmberg, unpublished) .

There are no indications of changes in abundance over the last 50 years.

Figures

FIGURE 7. Distribution of Zootoca vivipara in North Sweden. Although most of the Scandic Mountain range is colored, the species is absent from high-altitude areas in the Alpine region (see Figure 1 for outline of the latter). The upper limit of occurrence runs from 1100 m in Härjedalen, decreasing towards the north to 700–800 m in Lule lappmark. The only truly far offshore occurrence in the Baltic is shown by a triangle. A question mark denotes unknown status in parts of the vast Baltic archipelago in Norrbotten.

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.

FIGURE 13. Recently abandoned hayfields are prime summer habitat for Rana temporaria, R. arvalis, Bufo bufo, Anguis fragilis, and Vipera berus. The forest edge in the background is typical habitat also for Zootoca vivipara. Baggböle, Västerbotten, Middle Boreal region. Photo: Johan Elmberg.

FIGURE 14. Vast areas of North Sweden’s interior are covered by level open bogs with permanent water. Rana temporaria, R. arvalis, and Bufo bufo breed in the pool depressions (foreground) and come ashore to forage in grassy areas in summer. More elevated and drier string parts of the bogs offer protective vegetation and summer habitat för Zootoca vivipara and Vipera berus. Photo: Jonas Grahn.

FIGURE 19. Clear-cuts offer summer habitat for Zootoca vivipara, Anguis fragilis, and Vipera berus for a decade or so until planted conifers grow tall enough to shade the ground. Robertsfors, Västerbotten, Middle Boreal region. Photo: Johan Elmberg.