Smooth newt Lissotriton vulgaris and common toad Bufo bufo populations persisting in the unusually small area of Sommers Island in the Baltic Sea

Sommers Island is an abandoned 20 ha patch of land in the Baltic Sea. It is inhabited by isolated populations of smooth newt (Lissotriton vulgaris) and common toad (Bufo bufo). The island demonstrates the small area in which it is possible to have a stable population of newts and toads for a period of at least several decades, probably much longer. Most reproduction of both species occurred in one pool with an area of about 100 m². The total area of optimal terrestrial habitat is about 2.5 ha, with an additional 3.5 ha of sub-optimal habitat available. The island is inhabited by about 123 adult newts and several dozen adult toads.

Can We Share? Feeding Strategy in Three Syntopic Newts in Artificial Habitats

Natural aquatic sites are disappearing worldwide, especially in the Mediterranean region where amphibians are frequently forced to move for reproduction to artificial sites designed for irrigation and cattle watering (i.e., wells, tanks and drinking troughs). In artificial aquatic sites, where resources (space and food) are usually limited, trophic niche information can be particularly useful to infer the suitability of habitats for amphibian conservation especially when more than one species co-occurs. In this paper, we focused on three newt species: The Italian newt (Lissotriton italicus), the Italian smooth newt (Lissotriton vulgaris meridionalis) and the Italian crested newt (Triturus carnifex) inhabiting man-made wells widespread in an area in Central Italy characterized by few available natural aquatic sites. Specifically, we analyzed the trophic spectrum of the species, their interactions and overlap, and discussed the potential role of wells in amphibian conservation. Overall, 550 newt individuals occurring in 16 distinct wells were sampled. The study species consumed similar resources, mainly of aquatic origin, with Diptera larvae and Cladocera representing the most important preys. The high degree of diet overlap observed may be due to site oligotrophy and high availability of small-sized prey, and it does not necessarily lead to competition. Newts had similar narrow niche width values and a generalist feeding pattern with high diversity among individuals. Lissotriton italicus and T. carnifex showed wider niche width in isolation than in syntopy condition, probably as a result of interspecific competition and/or intraguild predation. We showed that artificial aquatic sites are important for newt ecology and conservation since they allow up to three species to cohabit, thus representing a good surrogate of natural habitats. The study wells apparently provided suitable trophic conditions for newts in terms of prey availability and catchability. To date, just a few studies have contributed to a greater understanding of newts’ diet in artificial aquatic sites and this gap of knowledge has to be filled to clarify their role in amphibian ecology and conservation.

Rediscovery of the Caucasian Smooth Newt, Lissotriton lantzi (Wolterstorff, 1914) (Salamandridae, Amphibia) in North Ossetia–Alania

Lantz’s newt, or the Caucasian smooth newt, Lissotriton lantzi, is an endemic species for the Caucasian mountain-forest belt. In North Ossetia–Alania, only 4 findings of this newt are known in the Prigorodniy, Alagirskiy and Irafskiy districts. Since 1983, there has been no new information about any findings of L. lantzi in this region. On August 4, 2020, L. lantzi larvae were caught in a lake on the left shore of the Urukh River in the Irafskiy district. Newts live here in a beech forest at an altitude of 810 m. The authors assume that L. lantzi in North Ossetia–Alania inhabits the entire forest belt in the range of altitudes of 700–1000 m above sea level.

Reproductive characteristics of the Caucasian smooth newt, Lissotriton lantzi (Wolterstorff, 1914) from Abrau Peninsula (Northwest Caucasus, Russia)

The publication presents results of the reproductive biology study of the Lissotriton lantzi (Wolterstorff, 1914) from the Abrau Peninsula (Krasnodar Territory, Russia). Ten females and ten males of this species were caught before breeding began. Animals were kept in plastic containers with water at a temperature of 11.5–23.0°C, one pair of newts in each container. Every day the reproductive behavior was recorded and laid eggs were selected. Males showed reproductive behavior (mating dance and position of spermatophore) within 1–36 days after the start of the research. Position of first eggs was observed in different females from 6 to 16 of April at a water temperature of 13.0–16.5°C. All ten females bred in April and May, only five females laid eggs in June and three females in July. The total duration of the oviposition period in different females was 41–99 days. Last eggs were found from May 26 to July 18 at a temperature of 17.5 to 23.0°C. Fertility of females in the breeding period was 67–832 eggs. The eggs of newts had a length of 3.1–4.0 mm and width of 1.9–2.8 mm. The duration of egg incubation at a temperature 14.5–20.5°C was from 13 to 24 days. Pre-larvae length after the hatching was equal to 6.5–9.8 mm. The larvae started to eat during 0–5 days after hatching. The length of larvae at the beginning of exogenous feeding was 8.2–11.3 mm. It is noted that most of the studied females (9 out of 10) had higher fertility than previously noted for this species (283–832 against 70–220 eggs).

Moderate consistency in smooth newt behaviour

Behavioural consistency (i.e., personality) is a novel field of research in amphibians. Current published studies often address only one or two aspects of personality and therefore cannot assess more complex relationships and behavioural syndromes. This is the first study focusing on all relevant behavioural traits and their relationships in urodele amphibians. Based on the three trials of the experiment, we examined the consistency of activity (time spent moving), boldness (latency of the first movement and time spent escaping) and exploration (number of visited segments of testing arena) of 42 smooth newts (Lissotriton vulgaris). Individual consistency, calculated through the intraclass correlation coefficient (ICC), was low in newt activity (ICC = 0.192) and moderate in boldness (0.476) and exploration (0.403). Activity was moderately consistent for each trial (0.425), indicating a possible habituation, supported by a decrease of mean activity throughout the trials. Correlation of the behavioural traits studied suggests the presence of a behavioural syndrome, which potentially shaped the traits together. Our findings suggest the need for a complex approach to the study of amphibian personality and the need for standardized methodology, which would solve the current difficulties in comparing published results.