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267In a field study in south central Sweden, we analysed the diversity of macrophytes in paired samples of ponds in a total of five geographically separated sites. Each pair of ponds involved one pond with presence of great crested newts (Triturus cristatus) and one pond in which newts were absent. Ponds with presence of great crested newts had a significantly higher mean number of plant species than ponds without newts. Newts occurred in ponds that tended to have a lower amount of pond area covered by surface vegetation, although this difference was not statistically significant. Macrophyte diversity also tended to increase more steeply in ponds with T. cristatus, compared with ponds without newts. Broad-leaved pond weed (Potamogeton natans) and square-leaved liverwort (Chiloscyphus pallescens) were among the plants that were most associated with presence of great crested newts. Plant diversity had a slightly more nested structure for ponds with great crested newts than for those without, which indicates a more homogeneous plant species assemblage in the former group of ponds. Overall, the results indicate that the great crested newt may be a reliable and useful indicator species for high plant species richness in ponds and small wetlands, which may be valuable for environmental monitoring and conservation in pond landscapes.
This study examined the hypothesis that numbers of newts captured were correlated with the phase of the moon. During the spring of 2008 smooth newts and great crested newts were captured in bottle traps laid in two ponds at Riseholme Park, University of Lincoln, UK. Highest rates of capture for smooth newts were either side of the new moon but for great crested newts the highest rate was immediately before the new moon. Identification of individuals showed that during the observation period smooth newts regularly moved between aquatic and terrestrial habitats, but great crested newts appeared to leave ponds and did not return. This is the first report that numbers of newts captured are affected by the lunar cycle. Activity during the darkest nights may limit the risk of predation as individuals leave breeding ponds to forage on land or to move between ponds. These results have implications for surveys of newt breeding sites because lack of individual identification and trapping events at the wrong time of the month can both seriously undermine estimates of population sizes.
Data on the body size in the superspecies Triturus cristatus. The greatest total length so far known is 209 mm, reached in captivity by a female of Triturus carnifex from Florenca (Italy).
The newts Triturus vulgaris and Triturus montandoni are sister species that exhibit contrasting levels of intraspecific morphological variation. Triturus vulgaris has a broad Eurasiatic distribution encompassing both formerly glaciated and unglaciated areas and shows substantial morphological differentiation in the southern part of its range, while T. montandoni, confined to the Carpathians, is morphologically uniform. We analysed sequence variation of two mtDNA fragments of the total length of c. 1850 bp in 285 individuals of both species collected from 103 localities. Phylogenetic analysis of 200 unique haplotypes defined 12 major clades, their age estimated at c. 4.5–1.0 million years (Myr). Most of the older clades were found in the southern part of the range, and also in central Europe, mainly in Romania. The distribution of mtDNA clades points to the existence of several glacial refugia, located in the Caucasus region, Anatolia, the Balkan Peninsula, Italy, and more to the north in central Europe. The concordance between mtDNA based phylogeny and the distribution of T. vulgaris subspecies was weak. Triturus montandoni haplotypes did not form a monophyletic group. Instead they were found in six clades, in five of them mixed with T. vulgaris haplotypes, most likely as a result of past or ongoing hybridization and multiple introgression of mtDNA from T. vulgaris to T. montandoni. Patterns of sequence variation within clades suggested long-term demographic stability in the southern groups, moderate and relatively old demographic growth in the populations inhabiting central Europe, and high growth in some of the groups that colonized northern parts of Europe after the last glacial maximum.
Crested newts eat mainly invertebrates, but may also ingest vegetal particles, Amphibian eggs or shed skins. Besides the shed skins of conspecific individuals, we have also identified shed skins of Bombina variegata, and even of Lacerta agilis. Due to the particular morphology of the habitat, the coming of the warm season brings about differences in the accessibility of different prey categories from one part to another of the Şinteu pond. This difference in the trophic offer causes modifications in the trophic spectrum, the adoption of the “sit-and-wait” feeding strategy, an increase in the number of empty stomachs, and indicates a decrease in the preying capacity of newts that prepare to leave the aquatic environment. Quantitatively, the most important prey taxa to the studied population are tadpoles and Nematocera larvae.
