Syrian common toad
| Syrian common toad | ||||||||||||
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Syrian common toad ( Pelobates syriacus ) |
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| Scientific name | ||||||||||||
| Pelobates syriacus | ||||||||||||
| Boettger , 1889 |
The Syrian sea toad ( Pelobates syriacus ) is a frog and belongs to the genus of the European sea toads ( Pelobates ) within the family of Pelobatidae . With the sharp-edged, calloused growths on the soles of their feet, like the other paddock toads, they can very quickly bury themselves in loose soil, where they spend the day. The Syrian sea toad is widespread in the Balkans and as far as the Middle East.
features
The Syrian common toad has a body length of about 80 to 90 mm. The back color is brownish, gray or white with greenish or dark brown spots. The ventral side is whitish in color and unspotted. The skin is smooth with a few, often red-colored glandular warts.
The pupil is slit vertically and, unlike the common spadefoot toad, the middle of the head is not arched like a helmet. Like its relatives, the animal has heavily notched webs , the notch of which is even more pronounced than that of other paddock toads. It also has light brown heel bumps at the base of the first toes, which are designed as hard digging shovels.
distribution
The distribution area of the Syrian common toad stretches from the southern Balkans to Iran , but the population is not uniform. In Serbia, Bulgaria and Romania, the Syrian common toad occurs along the Danube and its tributaries, further on the coast of the Black Sea, in North Macedonia almost all over the country. In Greece, the area covers the entire mainland. In Anatolia the regions on the Aegean Sea and the Mediterranean Sea belong to the distribution area, Pelobates syriacus has also been proven on the Black Sea coast and in some localities in Eastern Anatolia. The species also populates Dagestan, Azerbaijan, Georgia, Armenia and Nakhichevan. In Iran, the sites are limited to a small part of the country in the northwest and the south coast of the Caspian Sea. There is evidence for Lebanon and Jordan. In Israel, the range includes the coastal plain, Galilee and the Golan Heights.
In many areas of its range, Pelobates syriacus is a lowland species, because the habitats are located on the seashore or lower reaches of rivers and extend from sea level to a few hundred meters in the adjacent mountains. In Greece about half of the habitats are below 50 meters above sea level. NN. The highest locations were found in the east of the distribution area, in Georgia at 950 meters, at Lake Van in Eastern Anatolia at 1650 meters and up to 2000 meters at the Arax River in Armenia and Nakhichevan.
In the areas along the Danube, on the west coast of the Black Sea, on the Bosphorus and in Dagestan, Pelobates syriacus and Pelobates fuscus are sympatric. Haifa is the terra typica of Pelobates syriacus .
Habitat and way of life
The animals prefer open, steppe-like landscapes (coastal dunes or agricultural areas) and light forests as their habitat.
The species is nocturnal. Most of the day they spend the day in self-dug, vertical earth tubes with a diameter of 2 to 5 centimeters and a depth of 5 to 25 centimeters. The diameter depends on the size of the animals. The common paddock dig shallow caves in spring and deep caves on hot summer days as it is cool and humid in them. Some paddle toads look for day hiding under stones or leaves.
The daily activity phase begins shortly after sunset. The turtles leave their burrows and hiding spots and look for food while they are on the surface of the earth. They cover distances of 1 to 15 meters. Two activity maxima can be seen, the first about an hour after it appeared on the earth's surface, the second, smaller about 1 hour before sunrise, the activity is lowest between two and three o'clock. The activity phase ends shortly before sunrise. As a resting place for the day, the toads usually dig new burrows or choose hiding places on the surface. When it is dry and at high temperatures, they sometimes stay in hiding for several days before they go looking for food again.
As winter quarters, the spadefoot toads dig deep caves; in Greece they are up to 50 centimeters deep, in the Caucasus up to 75 centimeters or even deeper. The common toads almost always hibernate individually in the caves, only occasionally several have been found. In Greece the hibernation begins at the end of November, in Armenia in October or November and ends in the lowlands after 2.5 to 3 months, in higher altitudes after 4 months.
When touched, the common toads release a defensive secretion that smells strongly of garlic , at the same time they puff up and give scare calls. In this behavior they resemble the closely related common garlic toad.
Reproduction
In Pelobates syriacus, reproduction almost always begins immediately after leaving the winter quarters and lasts only a few days. The beginning and duration depend on the local weather conditions, the altitude and the geographical latitude. In Greece, reproduction begins between February 15 and March 15 and lasts two to five days. In Bulgaria (Cresna region) reproduction takes place in early April, in Romania in April and May. Near Izmir in western Turkey, it takes place in January and February, in northern Israel from March to April. In Armenia and Azerbaijan, reproduction takes place in the low-lying areas from the end of March to the beginning of April, in the mountain regions of these countries, however, not until the beginning of June.
For reproduction, the Syrian turtle toads prefer temporary waters that form in natural depressions after extensive rainfall, for example from January to March in Greece, and have a size of a few square meters up to 50 square meters and are up to 40 centimeters deep. The common spadefoot toads also often spawn in temporary waters that are near rivers and lakes and have a water depth of 50 to 70 centimeters. Large permanent bodies of water are usually only visited for spawning in very dry years. In high-lying waters in the east of the range, however , Pelobates syriacus only spawns in permanent waters and lakes with a water depth of 2 to 2.5 meters.
pairing
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The migratory sea toads to the spawning waters usually take place after rainfall and begin at dusk. Males and females migrate to the waters at the same time, covering 100 to 500 meters. The majority of the sea toads arrive in the water between 8 p.m. and 9 p.m. There they go to the deeper area and initially remain motionless for several hours. During this time they absorb water.
The males then swim around on the surface of the water and make mating calls, or they choose locations in the shallow bank area to call so that the front body is outside the water and call from here (illustration) or they call underwater from the bottom of the water. The females also swim around, also making calls and approaching the males. The result is the amplexus, in which the males clasp the females in the groin (lumbar amplexus) (illustration). Spawning usually happens in the early morning hours, according to observations near Thessaloniki between four and six o'clock. The spawn is deposited at a depth of 10-15 centimeters and attached to plants. After spawning, the males release their grip, the females leave the spawning water immediately, as do almost all males, only a few remain for one or two days.
The females lay the eggs in the form of spawning cords that contain between 2000 and 4000 eggs. Immediately after laying, the length of a spawning line is 1.5 to 2 meters in older females and 0.75 to 1.2 meters in younger females. According to reports, there are spawning lines with a length of several meters. When water is absorbed, the jelly surrounding the eggs swells, making the spawning lines shorter and thicker. Each spawning cord consists of two double rows of cords, thus four cords that come from the two ovaries.
Calls
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Syrian spear toads do not have sound bladders, so the mating calls are not particularly loud. In the case of the sea toads that call on the surface of the water, the human ear can still hear the calls from a distance of 25-30 meters, the calls of the males calling under water can only be heard up to about 20 meters.
The pairing calls consist of a sequence of three to nine uniformly sounding groups of impulses that are separated by intervals. Such a sequence of pulse groups forms a call. The pulse groups start with two individual pulses, followed by a number of pulses, the amplitude of which is high at the beginning and rapidly decreasing (figure). Because of the construction of impulses, the impulse groups sound croaky. At a water temperature of 15.2 ° Celsius, the pulse groups last an average of 132 milliseconds and the intervals 255 milliseconds. As the water temperature rises, the duration of the pulse groups and the intervals decrease. The frequency range extends from around 400 Hertz to almost 2000 Hertz and has a dominant range at around 600 Hertz.
Females utter calls of liberation when the eggs have been released during mating. They use it to signal the males to end the amplexus. Males also give calls of liberation when they are clutched by other males. In captivity, the toads respond with calls to rescue when they are caught with the fingers in the loin area.
The liberation calls have the same structure as the pairing calls and sound very similar. Both the pulse groups and the intervals, however, are shorter than for the pairing calls. The number of impulse groups that build up a call depends on the duration and intensity of the grip they are resisting.
Young toads sometimes emit alarm calls when they are startled in their hiding place, and adult toads utter it when predators catch them during spawning. Shock calls are not similar to the mating or liberation call, but rather like a scream. They are expelled with the mouth open.
development
Freshly laid eggs are spherical and two-colored. The animal pole and the adjoining part of the eggs are dark brown up to the middle, the vegetative pole is cream-colored. The diameter of ungrooved eggs is 1.4 to 1.8 millimeters, and already at the blastula stage it is 10-15% larger. At a water temperature of 15 to 25 ° Celsius, the larvae hatch after 5 to 6 days. They are around 4 millimeters tall. The larval period, the time from spawning to metamorphosis, lasts 2.5 to 3 months in temporary waters. The tadpoles reach a stately size. In Greece, the maximum size with normal development is 90-120 millimeters, wintering tadpoles can reach 118-120 millimeters.
In Greece, after the metamorphosis, the young paddock toads have a size of 22-26 millimeters, the weight is 2.5-3.5 grams. In Bulgaria, the young toads measure 28-30 millimeters after metamorphosis and weigh 3.3 grams. Male green toads reach sexual maturity in the second year, the females in the third year.
nutrition
Pelobates syriacus tadpoles feed primarily on plant material, and to a lesser extent on plankton. In Greece, Ranunculus trichophyllus , hair-leaved water crowfoot, serves as food, which grows on a large scale in temporary bodies of water. During the flowering period of the plant in April, it is the main food source for the tadpoles, which prefer to eat the flowers.
Adult Pelobates syriacus have a very wide range of food that changes over the course of the year depending on the availability of the prey. Mainly insects such as Orthoptera, Coleoptera, Lepidoptera, Hymenoptera and Dermaptera serve as food, in addition also millipedes, spiders, isopods, furthermore gastropods and earthworms. Captive toads do well with Tenebrio (mealworms and beetles), Acheta, and Gryllus.
Systematics
The Syrian sea toad and three other closely related species of the genus European sea toads ( Pelobates ) usually form an independent family Pelobatidae. In addition to the common spadefoot toad ( P. fuscus ), these include the knife foot ( P. cultripes ) and the Moroccan knife foot ( P. varaldii ).
Danger
In the IUCN Red List of Threatened Species, the Syrian turtle is classified as Least Concern because it has a relatively large range and is believed to have a relatively large total population. However, there are regional threats from habitat destruction or water pollution.
Several causes are named for the decline in populations. First and foremost is the destruction of habitats, both terrestrial and aquatic, through building or road construction, as well as the intensification of agriculture and the associated pollution of the soil with pesticides and other chemicals.
literature
- Axel Kwet: Reptiles and Amphibians of Europe. Franckh-Kosmos Verlag, Stuttgart 2005, ISBN 3-440-10237-8 , p. 74.
- Theodora S. Sofianidou: Pelobates syriacus (Boettger 1889) - Syrian spade toad. In: Kurt Grossenbacher (Ed.): Handbook of the reptiles and amphibians in Europe. Volume 5 / I: Froschlurche (Anura) I. AULA-Verlag, Wiebelsheim 2012, ISBN 978-3-89104-006-5 , pp. 563-620.
- Jean-Pierre Gasc, Antonia Cabela, Jelka Crnobrnja-Isailovic, Dag Dolmen, Kurt Grossenbacher, Patrick Haffner, Jean Lescure, Harald Martens, Juan Pablo Martínez Rica, Hervé Maurin, Maria Alisa Oliveira, Theodora S. Sofianidou, Michael Veith, Annie Zuiderwijk (Ed.): Atlas of Amphibians and Reptiles in Europe. Societas Europaea Herpetologica and Muséum National d'Histoire Naturelle (IEGB / SPN), Paris 1997, ISBN 2-86515-103-4 , 496 pp.
- Christoph Dufresnes, Ilias Strachinis, Elias Tzoras, Spartak N. Litvinchuk, Mathieu Denoël: Call a spade a spade: taxonomy and distribution of Pelobates, with description of a new Balkan endemic. In: ZooKeys. Volume 859, 2019, pp. 131-158, doi: 10.3897 / zookeys.859.33634 .
- Christoph Dufresnes, Ilias Strachinis, N. Suriadna, G. Mykytynets et alt .: Phylogeography of a cryptic speciation continuum in Eurasian spadefoot toads (Pelobates). In: Molecular Ecology. Volume 28, No. 13, 2019, doi: 10.1111 / mec.15133 .
- Darrel R. Frost: Pelobates syriacus Boettger, 1889. In: Amphibian Species of the World: an Online Reference. Version 6.0. American Museum of Natural History, New York 1998–2020, doi: 10.5531 / db.vz.0001 , accessed November 7, 2020.
Individual evidence
- ↑ a b c d e f g h i j k Theodora S. Sofianidou: Pelobates syriacus (Boettger 1889) - Syrian shovel toad. In: Kurt Grossenbacher (Ed.): Handbook of the reptiles and amphibians in Europe. Volume 5 / I: Froschlurche (Anura) I. AULA-Verlag, Wiebelsheim 2012, ISBN 978-3-89104-006-5 , pp. 563-620.
- ↑ Lyudmila F. Mazanaeva, Azim D. Askenderov: New data on the distribution of eastern spadefoot, Pelobates syriacus Boettger, 1889, and common spadefoot, Pelobates fuscus Laurenti, 1768, in Dagestan (The North Caucasus). In: Russian Journal of Herpetology. Volume 14, No. 3, 2007, pp. 161-166, doi: 10.30906 / 1026-2296-2007-14-3-161-166 .
- ↑ Otto Boettger: A new Pelobates from Syria. In: Zoologischer Anzeiger. Volume 12, No. 297-324, 1889, pp. 144-147 ( digitized version ).
- ↑ SB Papanian: On the ecology of Pelobates syriacus in the conditions of Armenia. In: Izvestiya Akademii Nauk Armyanskoi SSR, Biologicheskie Nauki. Volume 12, No. 12, 1959, pp. 51-62.
- ^ A b c Theodora S. Sofianidou: Studies on the biology and ecology of Pelobates syriacus Boettger (Anura: Pelobatidae). Ph.-D. Thesis University of Thessaloniki, 1977.
- ↑ Pelobates syriacus in the endangered Red List species the IUCN 2007. Posted by: Kuzmin, S., Tarkhnishvili, D., Ishchenko, V., Ananjeva, N. Orlov, N., Tuniyev, B., Papenfuss, T. , Degani, G., Ugurtas, I., Sparreboom, M., Rastegar-Pouyani, N., Disi, A., Anderson, S., Gasith, A., Elron, E., Gafny, S. & Cogalniceanu, D., 2004. Retrieved July 19, 2008.
- ↑ George D. Džukić, Vladimir Beškov, Vesna Sidorovska, Dan Cogalniceanu, L. Miloš Kalezić: Historical and contemporary ranges of the spadefoot toads Pelobates spp. (Amphibia: Anura) in the Balkan peninsula. In: Acta zoologica cracoviensia. Volume 48A, No. 1-2, 2005, pp. 1-9, doi: 10.3409 / 173491505783995699 .
