Henrik Bringsøe // MERTENSIELLA #19 131-138 Februar 2013

13 cases of terrestrial height-seeking or climbing habits in Lissotriton vulgaris are reported, apparently for the first time. This behaviour seems to be unknown in all other Palaearctic salamandrid newt species. 12 observations were made from throughout Denmark and one from Germany, mainly during the terrestrial phase. The observations involved males, females and subadults in a wide variety of terrestrial habitats and microhabitats during the entire active season from February through October. The majority of observations were made at night or dusk, however, some were made in daylight. Most newts were fully exposed whereas a few were concealed. Particularly interesting was an observation made in mild weather in late winter when a male was seen climbing the vertical wooden outer wall of a house, approaching a lighted lamp farther up. The purpose was apparently to catch invertebrates, which were attracted by the light. It is considered likely that height-seeking newts are generally foraging when they are active and exposed. The fact that L. vulgaris is sometimes observed at elevated hiding places indicates that microhabitats above ground level are utilised regularly albeit much more rarely than on the ground. Additionally, one case of limited height-seeking in Triturus cristatus is reported.

Paul Edgar and David R. Bird // Сonvention on the Сonservation of European Wildlife and Natural Habitats, Strasbourg 2006

Børre K. Dervo, Jon Museth and Jostein Skurdal // Diversity 10(3):56, 5 July 2018

Construction of artificial overwintering habitats, hibernacula, or newt hotels, is an important mitigation measure for newt populations in urban and agricultural areas. We have monitored the use of four artificial hotels built in September 2011 close to a 6000 m2 breeding pond in Norway. The four hotels ranged from 1.6 to 12.4 m3 and were located from 5 to 40 m from the breeding pond. In 2013–2015, 57 Great Crested Newts (Triturus cristatus) and 413 Smooth Newts (Lissotriton vulgaris) spent the winter in the hotels. The proportions of juveniles were 75% and 62%, respectively, and the hotels may be important to secure recruitment. Knowledge on emigration routes and habitat quality for summer use and winter hibernation is important to find good locations for newt hotels. The study documented that newts may survive a minimum temperature of - 6.7 ⁰C. We recommend that newt hotels in areas with harsh climate are dug into the ground in slopes to reduce low-temperature exposure during winter.

Bernd von Bülow & Alexander Kupfer // Salamandra 55(2), 97–102, 15 May 2019

A population of Northern crested newts, Triturus cristatus, was studied for 19 consecutive years (1998–2016) using individual recognition allowing the quantification of population dynamics and survival rates. Starting with a relatively high estimated number of adults (251 ± 55) and a long stable phase (144 ± 25) the population dropped six-fold (39 ± 10) by the end of the study. The population failed to recruit in nine years including a reproduction failure over four consecutive years of the 19 year study period. The yearly adult survival ranged from 18 to 98% with no differences between the sexes. Likely related to relative favourable survival rates of individuals older than 4+ of age and adult longevity of more than 16 years the population persisted. More long-term studies are urgently needed to assess how population dynamics are subject to local environmental factors or demographic patterns of the population itself.

Brett Lewis, Richard A. Griffiths & John W. Wilkinson // Herpetological Journal, Volume 27 (April 2017), 133–142

Increasing development of natural habitats frequently causes conflict with the conservation of protected species. Consequently, interventions that attempt to mitigate the impact of development are becoming increasingly commonplace. We used four approaches to assess the effectiveness of development mitigation on a species subject to widespread development pressures in Europe – the great crested newt (Triturus cristatus). Firstly, a systematic evidence review revealed eleven published studies of great crested newt populations at development sites. None provided conclusive evidence that the mitigation carried out was effective in maintaining populations. Secondly, less than half of 406 mitigation licence project files examined contained reports of results. Of those that did, only 16 provided post-development population assessments. These included one extinct population, and 10 ‘small’ populations. Thirdly, standardised population assessments were carried out at 18 sites in England, at least six years after the initial mitigation was completed. Although newt populations persisted at most of these sites, there was evidence of an overall decline, with extinctions occurring at four sites. Fourthly, although the annual cost of mitigation for great crested newts in England is estimated at between £20-43 million, information on the status of populations and habitats makes it difficult to assess whether this is cost-effective for either conservation or development. The quality and quantity of available data make it difficult to assign reasons for population changes at mitigation sites, but the study highlighted four general issues concerning mitigation practice: (1) presence of non-viable populations pre-mitigation; (2) inadequate mitigation interventions and site management; (3) cumulative impacts of further developments; and (4) emergence of new threats post-mitigation. Nevertheless, it is possible that some mitigation activities may have unforeseen and undocumented benefits, such as providing green spaces and biodiversity enhancement in urban areas.

J. W. Arntzen and S. F. M. Teunis // Herpetological Journal, Vol. 3, pp. 99-110 (1993)

The population dynamics of the crested newt, Triturus cristatus, in a newly created aquatic habitat in a dune area in northwestern France was studied over a six year period. After a rapid colonization of the pond in year 1, 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.

Heiko Hinneberg, Eva-Maria Riedel, Katharina Foerster & Alexander Kupfer // SALAMANDRA 56(1): 57–65. 15 February 2020

Determining animals’ age is important for a wide range of study fields in biology. However, age determination is often problematic because it relies on invasive techniques. For the Northern Crested Newt (Triturus cristatus) various morphological traits are believed to be age-related. Quantifying interrelations among four morphological characteristics (snout–vent length, crest morphology, ventral colouration, tail base spot size), our study demonstrated that the traits are interrelated within and across populations. Both genetic and plastic adaptation to local environmental conditions unlikely explain the observed trait correlations. Furthermore, we found significant differences in snout–vent length and ventral colouration between adult and juvenile/subadult Crested Newts. Thus, there is strong evidence that the studied traits are age-related. Even though the ontogenetically mediated trait variation is masked by a non-age-related variability, the analysis of morphological traits serves as a powerful tool for obtaining insights into Crested Newts’ population demography in a non-invasive fashion.