Editing Northern crested newt (section)

==Life cycle and behaviour==

Like other newts, ''T. cristatus'' develops in the water as a larva and returns to the water each year for breeding. Adults spend around seven months of the year on land. After larval development in the first year, juveniles pass another year or two before reaching maturity; in the north and at higher elevations, this can take longer. The larval and juvenile stages are the riskiest for the newts, while survival is higher in adults. Once the risky stages passed, adult newts usually have a lifespan of seven to nine years, although individuals have reached 17 years in the wild.{{r|JehleThiesmeier2011|p=98–99}}

Adult newts begin moving to their breeding sites in spring when temperatures stay above {{convert|4|–|5|C|F}}, usually in March.{{r|JehleThiesmeier2011|p=44}} In the aquatic phase, crested newts are mostly nocturnal and, compared to smaller newt species, usually prefer the deeper parts of a water body, where they hide under vegetation. As with other newts, they have to occasionally move to the surface to breathe air. The aquatic phase serves not only for reproduction, but also offers more abundant prey, and immature crested newts frequently return to the water in spring even if they do not breed.{{r|JehleThiesmeier2011|p=52–58}}

During the terrestrial phase, the newts use hiding places such as logs, bark, planks, stone walls, or small mammal burrows; several individuals may occupy such refuges at the same time. Since the newts generally stay very close to their aquatic breeding sites, the quality of the surrounding terrestrial habitat largely determines whether an otherwise suitable water body will be colonised.{{r|1=JehleThiesmeier2011|p1=47–48,76|2=EdgarBird2006|3=Jehle2000}} Great crested newts may also climb vegetation during their terrestrial phase, although the exact function of this behaviour is not known at present.{{r|LynnAllain2022}}

The juvenile [[eft]]s often [[Biological dispersal|disperse]] to new breeding sites, while the adults in general move back to the same breeding sites each year. The newts do not migrate very far: they may cover around {{convert|100|m|yd}} in one night and rarely disperse much farther than {{convert|1|km|mi|spell=in}}. Over most of their range, they [[hibernate]] in winter, using mainly subterranean hiding places, where many individuals will often congregate.{{r|1=JehleThiesmeier2011|p1=73–78|2=EdgarBird2006}}

===Diet and predators===

Northern crested newts feed mainly on invertebrates. During the land phase, prey include [[earthworm]]s and other [[annelids]], different [[insects]] and their larvae, [[woodlice]], and [[snails and slugs]].<ref>{{cite web | url=https://amphibiaweb.org/species/4295 | title=AmphibiaWeb - Triturus cristatus }}</ref> During the breeding season, they prey on various aquatic invertebrates (such as [[mollusc]]s [particularly small [[bivalve]]s], microcrustaceans, and insects), and also [[tadpoles]] and juveniles of other amphibians such as the [[common frog]] or [[common toad]], and smaller newts (including conspecifics).{{r|JehleThiesmeier2011|p=58–59}}<ref>{{cite web | url=https://amphibiaweb.org/species/4295 | title=AmphibiaWeb - Triturus cristatus }}</ref> Larvae, depending on their size, eat small invertebrates and tadpoles, and also smaller larvae of their own species.{{r|EdgarBird2006}}

The larvae are themselves eaten by various animals such as carnivorous invertebrates and [[water birds]], and are especially vulnerable to predatory fish.{{r|EdgarBird2006}} Adults generally avoid predators through their hidden lifestyle but are sometimes eaten by [[herons]] and other birds, snakes such as the [[grass snake]], and mammals such as [[shrew]]s, [[European badger|badgers]] and [[European hedgehog|hedgehogs]].{{r|JehleThiesmeier2011|p=78}} They secrete the poison [[tetrodotoxin]] from their skin, albeit much less than for example the North American [[Taricha|Pacific newts]] (''Taricha'').{{r|WakelyFuhrman1966}} The bright yellow or orange underside of crested newts is a [[warning coloration]] which can be presented in case of perceived danger. In such a posture, the newts typically roll up and secrete a milky substance.{{r|JehleThiesmeier2011|p=79}}

===Courtship and reproduction===
{{See also|Triturus#Reproduction}}

[[File:Courtship of northern crested newt (Triturus cristatus).webm|thumb|left|alt=Video of crested newt courtship behaviour filmed underwater in a pond|Northern crested newt courtship in a pond, with male showing "lean-in" and tail-flapping behaviour]]

Northern crested newts, like their relatives in the genus ''Triturus'', perform a complex [[courtship display]], where the male attracts a female through specific body movements and waves [[pheromones]] to her. The males are territorial and use small patches of clear ground as [[lek mating|leks]], or courtship arenas. When successful, they guide the female over a [[spermatophore]] they deposit on the ground, which she then takes up with her [[cloaca]].{{r|JehleThiesmeier2011|p=80–89}}

The eggs are fertilised internally, and the female deposits them individually, usually folding them into leaves of aquatic plants. A female takes around five minutes for the deposition of one egg. They usually lay around 200 eggs per season. Embryos are usually light-coloured, 1.8–2&nbsp;mm in diameter with a 6&nbsp;mm jelly capsule, which distinguishes them from eggs of other co-existing newt species that are smaller and darker-coloured. A [[Chromosome No. 1 syndrome|genetic particularity]] shared with other ''Triturus'' species causes 50% of the embryos to die.{{r|1=JehleThiesmeier2011|p1=61–62|2=HornerMacgregor1985}}

Larvae hatch after two to five weeks, depending on temperature. As in all salamanders and newts, forelimbs develop first, followed later by the back legs. Unlike smaller newts, crested newt larvae are mostly [[nektonic]], swimming freely in the water column. Just before the transition to land, the larvae [[wiktionary:resorb|resorb]] their external gills; they can at this stage reach a size of {{convert|7|cm|in}}. [[Metamorphosis]] into terrestrial [[eft]]s takes place two to four months after hatching, again depending on temperature. Survival of larvae from hatching to metamorphosis has been estimated at a mean of roughly 4%. In unfavourable conditions, larvae may delay their development and overwinter in water, although this seems to be less common than in the small-bodied newts.{{r|JehleThiesmeier2011|p=64–71}}

{{Multiple image
|header=Development in the northern crested newt
|total_width=800
|align=center
|image1=OpenedLeafwithEggOfTriturusCristatus.JPG
 |caption1=Embryo in jelly capsule
 |alt1=A transparent egg with a white embryo on the leaf of an aquatic plant
 |width1=2288
 |height1=1712
|image2=TriturusCristatusYoungLarva.JPG
 |caption2=Young larva
 |alt2=A newt larva with gills and forelimbs, but no hindlimbs developed
 |width2=2272
 |height2=1704
|image3=TriturusCristatusLarvaAlmostGrown.jpg
 |caption3=Larva shortly before metamorphosis
 |alt3=A dark-coloured larva with all limbs developed but gills still apparent
 |width3=2272
 |height3=1704
|image4=Noerdlicher-Kammmolch-triturus-cristatus.jpg
 |caption4=Terrestrial juvenile
 |alt4=A small, black newt without gills or crest on mosstaxobox
 |width4=3744
 |height4=2262
|footer= ''Triturus'' species fold their eggs in leaves of aquatic plants. The larvae first develop fore- and later hindlimbs and can grow up to 7 cm. After metamorphosis, juveniles are around 3–5 cm long. In total, larval development takes between two and four months.
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}}