Dmitriy V. Skorinov, Emin Bozkurt, Kurtuluş Olgun and Spartak N. Litvinchuk // Acta Zoologica Academiae Scientiarum Hungaricae 68(3), pp. 261–276, 2022

The location, shape and area of dark spots on the belly, throat and sides of the body of three closely related species of smooth newts (Lissotriton kosswigi, L. schmidtleri and L. vulgaris) were analysed. Differences were found between species and sexes in the location and shape of dark spots on the belly, throat and lateral surfaces of the body. Discriminant analysis of these spot characteristics allows to identificate of males of all three species with a high degree of confidence (85–91%). In females, only L. vulgaris was correctly distinguished from the other two species (accuracy 81–94%). Anatolian and Thracian populations of L. schmidtleri have very similar patterns of dark spots, which confirm their conspecificity. The differences in the location and size of dark spots make possible successful identification of the species during field research and study of museum specimens. The developed method could be useful for comparative studies of other animal species which have spotted camouflage or aposematic colouration.

Hangström Torkel // Zoologica Scripta. Vol. 6. 61 - 68, 1977

Growth of adult newts in southwestern Sweden has been studied from 1969 to 1972 in two ways: (1) The age of alcohol-preserved specimens has been determined by counting dark zones, which are thought to indicate hibernations, on transverse sections of bones (femur or humerus); and average body length and head width of the different age classes have been recorded and compared; (2) Free-living individuals have been identified by their ventral pattern, and body length and head width in different years have been recorded for each specimen. There was generally a small annual increase in body length and in head width, although the individual variation was large because some do not grow at all. Differences in growth were found between years, between populations and between sexes. It is concluded from these results that size should not be used for estimating the age of adult newts.

Malacarne Giorgio & Cortassa Rita // Animal Behaviour, 31(4), 1983, 1256–1257

 John M. R. Baker And Tim R. Halliday // Herpetological Journal. Vol. 10, pp. 173 - 176 (2000)

Variation in dorsal crest morphology and tail height in males of a population of great crested newts (Triturus cristatus) was examined in relation to putative age. Newts were divided into three age classes according to the number of years that they had been recorded in the breeding Population:= first-year breeders, second-year breeders and long-term breeders. Crest morphology differed between the age classes, with a tendency for the crest's teeth to be more irregular in older males. We believe this is the first recorded evidence of age-dependent variation in a sexually selected, morphological character in an amphibian. However, it remains to be tested whether females distinguish between males on the basis of crest morphology. Body size (snout-vent length) and tail height, which is strongly correlated with crest size, also differed between the age groups: body size increased with age and males breeding for the first time had tails that were less tall than those of older animals.

John M.R. Baker // Animal Behaviour, 1992, 43, 157 - 159

Tommy Karlsson, Per-Eric Betzholtz and Jan C. Malmgren // Web Ecology 7: 63–76. (2007)

Viability and sensitivity of the great crested newt Triturus cristatus were simulated under different scenarios with a demographically and spatially structured stochastic model in an area of 144 km2 in southeastern Sweden. Eighteen ponds were monitored using drift fences with pitfall traps, funnel traps, visual observation and netting during the spring and summer of 2004. Estimated adult population sizes ranged between 0 and 620 individuals and the mean (±SD) local population size was 297±233 individuals. Due to uncertainty of the data, the model was simulated with parameter ranges to estimate upper and lower bounds of viability. Estimated quasi-extinction risk (the risk of each population in the study area falling below 10 females) within a 50-year period ranged from 100% to 0%, with a “best” estimate of 19.2%. The parameter most sensitive for the model outcome was fecundity, followed by juvenile survival, adult survival and transition from juvenile to adult. When these parameters were set at their lower bound, the quasi-extinction risk increased to 80–100%, while simulating these parameters at their higher bound inferred no or nearly no risk of quasi-extinction. This highlights the importance of focusing conservation efforts and research on the early life cycle stages. Management measures such as restoration of ponds and increased pond density decreased the risk for the great crested newt to end up quasi-extinct in the study area after 50 years. The results may have implications on management measures of great crested newts throughout its distribution area.

Lukáš Weber, Jan Růžička, Ivan H. Tuf, Martin Rulík // Herpetozoa 36: 345–356 (2023)

In animals, migration is an evolutionary adaptation to manage seasonally varying habitats. Often driven by climatic changes or resource availability, amphibians then migrate from their hibernation sites to their breeding grounds. This research focused on the migratory habits of the Great crested newt (Triturus cristatus). The study explored factors like gender, body size, and environmental determinants, noting that immigration and emigration events proved distinct during the year. Results unveiled that males typically reached ponds first, with temperature being pivotal: males preferred up to 5 °C, females around 10 °C, while juveniles moved as temperatures increase. Wind velocity affected larger newts, around 120 mm, prompting them to migrate with stronger winds. Notably, heavy rainfall favored migration of newts of roughly 60 mm size. Humidity displayed gender-based trends: males associated positively with average levels, females showed aversion above 50%, and juveniles leaned towards drier conditions. Emigration patterns mirrored these findings, emphasizing roles of temperature, wind, and humidity. The effect of moonlight is not statistically significant. These findings provide valuable insights into the environmental factors influencing the migration of T. cristatus, which may guide future conservation efforts.

J. W. Arntzen And S. F. M. Teunis // Herpetological Journal. Vol. 3. pp. 99- 1 1 0 (1993) 

The population dynamics of the crested newt, Triturus cristatus. in a newly created aquatic habitat in a dune area in northwestem France was studied over a six year period. After a rapid colonization of the pond in year I, and a fast initial increase to reach 335 newts in year 5, the adult population size dropped dramatically to 16 in year 7. Variation in the adult population among years was largely due to variation in juvenile recruitment. In the longer term. the population stabilized at about 40 newts. Since the population has survived for five times the minimum generation time of the species, the colonization was judged to be a success. An estimated 50% of the juveniles joined the breeding population at age 2; those that did not breed by then spent the third year on land. The average annual survival rate for the juveniles was 0.22. For the adults survival was 0.49 and showed almost no fluctuations over time or with age. Given a short distance to disperse, the crested newt can be an opportunistic species.

Richard A. Griffiths & Clair Williams // Rana (4), 2001. 239 - 247

Population Viability Analysis (PVA) provides a tool for assessing the risk of extinction in threatened species, but has rarely been applied to amphibian populations. Using existing life history data, we constructed several stochastic models to predict the effects of (1) progressive subdivision of crested newt habitat; and (2) different levels of juvenile dispersal between ponds, on the persistence of crested newt populations over a fifty year period. The models predict that small isolated populations have a higher risk of extinction than large isolated populations. In a subdivided population, increasing dispersal between subpopulations decreased the extinction risk of the metapopulation as a whole. Although the extinction risk of an individual isolated population is relatively high, the collective extinction risk of a group of such populations is lower than that of a single population with the same overall population size, even in the absence of dispersal. This appears to be a result of the asynchronous population dynamics that are generated in a group of isolated populations. A subdivided population may therefore persist for longer than a single population because it is
unlikely that all the subpopulations will go extinct at the same time.

Maletzky A., Pesta J., Schabetsberger R., Jehle R., Sztatecsny M., Goldschmid A. // Herpetozoa, 2004. 17(1/2): 75–82.

The lake "Ameisensee" (1,282 m a.s.l.) is situated in the Northern Calcareous Alps of Austria, and represents an important breeding site for six species of locally endangered amphibians (Triturus carnifex, T. vulgaris, T. alpestris, Rana temporaria, Bufo bufo and Bombina variegata). Estimated population sizes by means of the capture-mark-recapture method were 805 (2000) and 327 (2001) in T. carnifex, 2362 (2000) and 1637 (2001) in T. vulgaris, 1090 (2000) and 7027) in T. alpestris, respectively. These are the largest known populations of T. carnifex and T. vulgaris from above 1100 m altitude in Austria. The age of 21 73 carnifex, 18 T. vulgaris and 19 T. alpestris was assessed using skeletochronological techniques. The median age was 8 years in T. carnifex and T. alpestris, and 7.5 years in T. vulgaris. Maximum longevities were 16 years (T. carnifex), 11 years (T. vulgaris) and 10 years (T. alpestris). Concerning the age structure there were no significant differences observed between the populations of the three newt species studied.

Graham Bell // Ecological Monographs. Vol. 47, No. 3 (1977), pp. 279-299

After metamorphosis, smooth or common newts (Triturus vulgaris vulgaris [Linn]) disperse on land, where they live as juveniles before returning to the water as breeding adults. The population age—structure was obtained by dissecting the standard length frequency distribution, a procedure which is justified in the text. Juveniles have an uncomplicated age—structure, the number of individuals in successively later age—classes being reduced by mortality and by recruitment to the adult population. Among adult newts, the most frequent age—class is nearly central, indicating the existence of extensive variation in the age at maturity. Growth continues throughout life, the rate of growth decreasing with age. The annual survival rate of adult newts as estimated by a census method, and from the age—structure, was found to be ~ 50%, being rather greater in ♀ ♀ than in ♂ ♂. Less reliable data indicate the annual survival rate of juveniles was ~ 80%. Maturity is attained between the ages of 3 and 7 yr, most individuals reproducing for the first time at 6 or 7 yr of age. The number of eggs laid increases with age from ~ 100 at age 3 to ~ 400 at age 12; there is also an effect of ♀ age on oocyte size, which may influence subsequent larval survival. Smooth newts breed annually. Reproduction diverts surplus energy from somatic growth, and thereby decreases potential future fecundity in animals whose fecundity is proportional to body size. Individuals maturing at different ages, therefore, have different schedules of fecundity, which were estimated through the use of microbomb calorimetry. Population size was found to be lognormally distributed, with a mean of ~ 70. The sex ratio of juvenile newts was near equality, but a majority of ♀ ♀ comprised most adult populations. This imbalance is due to greater mortality of adult ♂ ♂, which results in an age—specific trend in the sex ratio. There are 2 breeding migrations: 1 in autumn and 1 in spring. It is likely that newts migrate during autumn when about to reproduce for the first time, and thereafter migrate during spring. Terrestrial newts appear to move little; there is some evidence that colonization of newly dug ponds is achieved by the infrequent emigration of juveniles. During its life, a smooth newt occupies a succession of ecological niches. Moreover, different individuals may occupy different niches, or may occupy the same niches for different periods of time. It is speculated that in large newt populations the complex life history is able to trap genetic variation and to dampen fluctuations in population size. However, it is suggested that these group attributes have arisen largely as the result of selection between individuals. Breeding only once (rather than repeatedly) will reduce fitness because the additional fecundity necessary to balance the loss of later reproduction cannot be attained. Early maturity appears to be favored in ♂ ♂ and late maturity in ♂ ♂ these opposed selection pressures may contribute to the observed age variation at maturity. Finally, the sex ratio does not vary with population density, and is therefore thought to be controlled by natural selection.

Hangström Torkel // Salamandra, 16 (4), 1980. 248-251

In a previous paper (HAGSTRÖM, 1977) the annual increase of body length in newts, Triturus cristatus (Laurenti) and Triturus vulgaris (Linnaues), was investigated. lt was found that there are considerable differences between individuals, between populations, and also between years. The material examined consisted of (1) free-living newts in two loca!ities, recorded for up to five successive years when the individuals were identified by their belly pattern (HAGSTRÖM, 1973 ), and (2) preserved newts from three other localities, each specimen agedetermined by counting skeletal growth marks on transverse sections of femur or humerus.

Берзин Д. Л., Вершинин В. Л. // Зоологический журнал, 2022, том 101, № 10, с. 1127–1135

Приведены анализ информации о распространении Triturus cristatus на восточном макросклоне Урала (Южный и Средний Урал) и актуальные сведения по исследованным популяциям. На основании мечения с повторными отловами впервые оценены численность репродуктивного ядра, соотношение полов, также изучена морфологическая специфика. С позиций оценки физико-химических особенностей среды местообитаний обсуждаются возможные лимитирующие факторы (термо- и влагообеспеченность, геохимические особенности, континентальность, наличие карстовых полостей, расселение инвазивных видов), оказывающие влияние на распространение и численность гребенчатого тритона на северо-восточной границе ареала.

Бородин П.Л. // Труды Мордовского государственного природного заповедника имени П.Г. Смидовича. 2024. Вып. 35. С. 23–46.

Обыкновенный (Lissotriton vulgaris Linnaeus, 1758) и гребенчатый (Triturus cristatus Laurenti, 1768), тритоны принадлежат к наиболее распространенным видам семейства Salamandridae Goldfuss, 1820 в лесном поясе Западной, Центральной и Восточной Европы. В основу данной работы положены ранее неопубликованные новые сведения о биоморфологических признаках молодняка в стадии перехода к наземной жизни на антропогенно преобразованном участке и в различных биотопах долины ручья Вальза на территории Мордовского заповедника. В ходе исследований получены новые материалы, уточняющие биологию этих видов. В ходе непрерывного 25084 суточного лова в долинном комплексе ручья Вальза Мордовского заповедника, включавшем в 1964–1973 гг. лесную поляну в пос. Пушта, вновь образованный в 1965–1967 гг. пруд на ручье Вальза в пос. Пушта, сосняки различного состава, смешанные леса, березняки, ольшаники, были получены сведения о биологии и основных морфометрических признаках 291 экземпляра молодняка Lissotriton vulgaris и 64 экз. Triturus cristatus самого раннего возраста.

Ширяев К. А., Терентьев Р. А. // Современная герпетология. 2024. Т. 24, вып. 3/4. С. 184 – 199

За всю историю наблюдений (по 2023 г. включительно) гребенчатый тритон Triturus cristatus (Laurenti, 1768) был найден в 39 локалитетах, расположенных на территории 12 из 23 административных районов Тульской области, при этом 23 местонахождения (59%) обнаружены за последние 4 года (2020 – 2023 гг.). Подавляющее большинство точек находок (92.3%) относятся к зонам хвойно-широколиственных и широколиственных лесов. В лесостепной зоне вид встречается реже, хотя в целом его распространение здесь изучено недостаточно. В Тульской области гребенчатый тритон проводит водную фазу жизни преимущественно в водоемах искусственного происхождения (71.4% из 28 случаев), что связано с дефицитом естественных стоячих и полупроточных водоемов вследствие расположения региона на Среднерусской возвышенности. Численность T. cristatus в выявленных в последние годы популяциях крайне низка (количество взрослых особей, учтенных в конкретном водоеме, никогда не превышало нескольких десятков). Обсуждаются специфические для вида лимитирующие факторы, среди которых в последние десятилетия особенно сильное влияние на распространение и численность гребенчатого тритона оказывает колонизация малых водоемов Тульской области ротаном Perccottus glenii Dybowski, 1877.