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The pond newt year

Already in early spring, from February / March, the pond newts are after the Hibernation active and wander purposefully to you Spawning waters, which is mostly close to the winter quarters. The first animals begin with the as early as April pairing. During the day you can also observe how the males courting around the females and depositing their seed carriers, called spermatophores, on the bottom of the water. The females take this up with the cesspool (internal fertilization) and days later they begin to deposit fertilized eggs on the aquatic plants. The mating game and egg-laying drag on until around June. Then the newts leave the water and spend the summer on land under stones and bark or in caves not far from the water. If these places are frost-proof, they will also be used for the duration of winter. Meanwhile, the development of the eggs continues in the pond: the larvae hatch and grow to a length of 3–4 cm by July. They are very voracious and look like with their outer tufts of gills little water monsters out. Eventually the transformation, often called metamorphosis, sets in and the little newts follow their parents into the country. Only in exceptional cases do some animals remain in the water and then keep the outer gills for a long time.
In the following, the various stages of the pond newt's life are explained in detail over the course of the year:

  • The pond newt mating dance
  • Larval development and metamorphosis
  • Food and enemies
  • wintering
  • Migratory behavior

The pond newt mating dance

Mating dance with pond newts; Photo: B. Trapp

The males start looking for a partner just 1–2 weeks after the newts migrate into the spawning waters. At the bottom of the water and swimming freely in the water, they court their partners. The male recognizes the female by her own fragrances Smell; this is called the orientation phase. If a female is recognized, the male first stands across in front of the female. Tail flaps are now carried out in several steps (the so-called. Whips) towards the body flank. Then fragrances are wagged at the water flow with the tail (Fan). The transverse position is finally abandoned and the partner who is ready to mate slowly crawls towards the male. This in turn causes the male to turn around and in the Waddling gait to crawl in front of the female. In the following mating phase, the female's snout touches the tip of the male's tail, which contracts the tail laterally and the pin-shaped one Spermatophores (Sperm carrier, gelatinous cone with a sperm packet at the tip) settles on the ground. The male crawls further and now stands head-on in front of the female, while the latter touches the tip of the male's tail and repeatedly presses his cloaca against the ground above the spermatophore and finally picks it up. The mating ritual can be repeated several times and with different males, but also females. The eggs are fertilized internally.

Female pond newt laying eggs; Photo: R. Podloucky

After 2–14 days, the females start with the Egg laying. The eggs are 1.3–1.7 mm in size and surrounded by a sticky gelatinous shell up to 3 mm in size. The female glues the eggs one at a time with her hind feet in the leaves of aquatic plants that she has folded. Depending on the age of the female, a total of 100-300 eggs are laid within several weeks. The egg-laying period is on average 37 days (with a range of 11–74 days), whereby the laying is temporarily interrupted because some females leave or change the mating waters so that the spawn can be spread over several waters. For this reason, the larvae of the pond newt are often found later in the year in ruts (wagon tracks) and puddles that are temporarily filled with water.

Larval development and metamorphosis

Young pond newt shortly after metamorphosis; Photo: W.-R.Grosse

The development time of the eggs depends on the respective water temperature. At 12 ° C the Embryonic phase (Development of the embryo in the egg shell) take up to 35 days. This is reduced to around 10–12 days at higher temperatures that change over the course of the day, such as those that prevail in sunny shallow water. The Larval phase (Development time from hatching to metamorphosis) begins with hatching from the egg. At this point the larvae are 6-8 mm long. Eyes, outer gill tufts and forelegs are easy to see with a magnifying glass. In the first time, the larvae remain quietly on aquatic plants, stems, etc. They attach themselves there with a sticky secretion from two adhesive organs in the mouth region and absorb them Yolk remains in the body cavity. Only days later do the larvae swim free and begin plankton and smallest aquatic animals to eat. Depending on the food supply and water temperature, they now develop quite quickly. The larvae are initially whitish to yellow and later turn light brown. Your top is now covered with dark brown pigment spots. The back hem, which begins at the head, remains almost pigmentless (in contrast to the larvae of the crested newt). Towards the end of the larval phase, the larvae have finally developed their hind legs and have now reached a total length of 3–4 cm. Depending on external factors such as temperature and food supply, the transformation from water to land life begins after 6–12 weeks (metamorphosis). In this phase, many larval features, such as gills and skin seams, are regressed. The entire development can be completed by mid-July, but the main metamorphosis time in Central Europe is in August. However, larvae were found late in December and hibernating larvae in spawning waters were also reported. The young newts, scientifically called juvenes, usually go ashore with a length of about 30 mm, with the range of 18–50 mm being very large. At first you find them Young animals at the edge of the water.

Neoten pond newt; Photo: H. Laufer

For the pond newt the phenomenon is the Neoteny described. This is understood to mean the retention of larval features, such as external gills and skin seams on the back and tail, and the simultaneous occurrence of sexual maturity. Neotene newts live permanently in the water and can deposit spermatophores or lay eggs. In Central Europe, however, such animals are the exception. In addition to neoteny, the causes of which are still largely unexplored and possibly have to do with disorders in the area of ​​the pituitary gland and its messenger substances (hormones), one also occurs more frequently in pond newts Developmental delay on. Due to low water temperatures, temporary lack of food or diseases of the thyroid gland, delays occur in the metamorphosis, which sometimes does not occur at all or occurs much later. Such permanent larvae usually do not reach sexual maturity, but diseases such as goiter lead to their rapid death.

food

Pond newt larvae eat “bite-sized” prey; Photo: S. Meyer

In the spawning waters, larvae and adults eat food through so-called. Suction snapwhere the opening of the mouth creates a suction that washes the food down the throat. On land, however, the newts grab their prey by simple means Snap with the pines. The prey is usually located optically through its movement or by means of odor recognition. The food is seasonally and regionally quite different. The Loot spectrum includes various "small animals" with a size that ostensibly matches the newt. For adult pond newts in the water v. a. the following prey animals detected: larvae of two-winged birds and dragonflies, hoppers, amphibian larvae and eggs, mussel crabs, swimming beetles, water lice and water fleas. Mosquito larvae, water snails, mayfly larvae, caddis fly larvae and various annelid worms (TubifexCalled snail gel). Thus a not insignificant part of the animal world of the small water bodies of Central Europe should belong to the range of prey of the pond newch; such species are called Food generalists. All the smallest forms of the food animals mentioned above are also prey of the pond newt larvae. In this context it has to be mentioned that the massive occurrence of pond newts in small bodies of water can make the reproduction of other amphibian species difficult. It is documented that pond newts eat the spawning balls of agile and common frogs and, above all, stalk the tadpoles that have just hatched from the egg; they do not stop at eggs and larvae of their own species. On land, pond newts mainly eat arthropods that live on the ground, such as spiders, woodlice, centipedes and many insect species and their larvae. Annular worms (earthworms, enchytrae) and snails (slugs and slugs) are also eaten.

Enemies

Grass snakes belong to the predators of the pond newts; Photo: S. Meyer

The larvae of pond newts are eaten by many predatory animal species that live in the water, e. B. of larger water beetles and their larvae as well as water bugs. All adult newts also eat pond newt larvae, and almost all fish can also be considered predators. Freshly transformed young newts on land are also eaten by larger ground beetles and by birds such as starling or magpie. Adult newts are prey for sea and pond frogs, grass snakes and dice snakes, white herons, gray herons, gulls, little grebes, mallards, marsh harriers, white storks and cranes. Random observations document other bird species and also some mammals as predators (shrews, hedgehogs, rats, water voles and weasels).

wintering

Both the transformed juveniles and the adult pond newts usually overwinter on land. The Central European deciduous forests offer the advantage that a layer of leaves covers the ground in autumn and thus provides a frost-proof cover. Further winter quarters can be found under stones and in cairns, in hollow tree stumps, in the system of gaps in the weathered rock, in gravel heaps and railroad embankments. Man-made structures such as dry stone walls, mine tunnels or stacks of material deposited in the open in the commercial areas that exist everywhere offer similarly good conditions for surviving the winter time. It is not uncommon for pond newts to crawl into underground cable trenches or cellar shafts, i. H., the supposed "lizard" in the basement is in most cases a newt, very often a pond newt. Hibernation in the water has also been observed several times in the pond newt. However, it is the exception. Nevertheless, pond newts have already been detected in the water during the winter months when ponds were drained, ditches were dredged or when water fleas were caught. As described above, the overwintering of newt larvae in the water is also a well-known phenomenon.

Migratory behavior

During the migration phase, pond newts are rather inconspicuous in color. The head furrows with glandular points are clearly recognizable; Photo: A. Kwet

In Central Europe, the largest part of the pond newts seems to be one occurrence in March to the waters to hike. However, it often happens that some of the males begin their migration as early as the end of February, when the temperatures on the ground are only 3–5 ° C. Precipitation is particularly beneficial after a previous dry period. Despite the early start of the season, the migration of mating-ready animals in a population often lasts until June. It can be observed that mostly only within a few days in April the majority of the animals in a population together in the water is to be found. After that, individual pond newts go ashore again or switch to neighboring bodies of water. The end of immigration is widely spread among both sexes. It is between late March and mid-May for males and from early April to mid-June for females. Taking into account many regional peculiarities, the average water stay for all occurrences is 2–3 months, and more rarely 4 months, in exceptional cases it is even 5.5–6 months. Since in almost all previous observations the animals were not known individually, a change of water or a temporary stay on land can only be assumed. However, studies with marked animals have shown that males spend less time on land during the spawning season than females. As a rule, a stay in the country does not last longer than three weeks. Towards the end of the spawning season, it can often be observed that the majority of the animals spend the day increasingly on land in hiding places under wood, leaves, in the herbaceous layer and the like and only occasionally return to the water at night. Be there daily routesup to 10 m covered. The Migration from spawning waters takes place from May to mid-July, depending on the region. The animals usually seek out the summer habitats in a targeted manner and use corridors such as paths, field edges or ditches on their hikes. The migration usually takes place in spurts, which are encouraged by heavy rainfall. Mass migrations of freshly transformed pond newts have also been observed. On average, an adult pond newt migrates 10–60 m to the summer habitat, but in individual cases it also migrates over 400 m up to 1 km known. In the case of new settlements in bodies of water, these distances may have been covered in several stages over years. The young can also be found along paths or diffusely distributed in the area. The tiny newts find protection from drought by searching for cracks or crevices under the substrate on the banks of the water. The migrations of the young animals are largely controlled by the weather, and after a long period of drought when it rains, active young animals can often be observed during the day. The main migration period for the young is between the end of July and the end of August. In summer and autumn, pond newts only cover short distances within their habitat. They can be found under the same stone or in the same crevice for weeks, except when searching for prey at night. Autumn hikes near the spawning waters are still known from some parts of the country. The winter quarters are visited between the end of September and mid-November.

Text source: campaign brochure 2010: The pond newt (download)

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