Fire-bellied toad
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European fire- bellied toad ( Bombina bombina ) |
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| ( Linnaeus , 1761) |
The fire-bellied toad ( Bombina bombina ), sometimes Tieflandunke or fire toad , belongs within the order of Anura to the " primitive " family Bombinatoridae and to the species of toads .
features
The head-torso length of males and females reaches only 45 (53) millimeters, whereby the Central European animals mostly remain smaller. Prophecies are so next to the tree frog and the more closely related midwife toad the smallest Central European Anura. In comparison to real toads , for example , the flat head with relatively closely spaced eyes, the overall flattened body, the lack of externally visible eardrums and ear glands ( parotid ) and the heart-shaped to triangular pupils are striking. At the mating season, the males can be distinguished from females by dark oestrus calluses on the forearm and the first two fingers; they also have large throat bladders (in contrast to the yellow-bellied toad ) that are visible when calling.
The top of the body is covered with flat warts, which have small black horn spines (not as distinct as in the yellow-bellied toad), light to dark gray or gray-brown with dark spots. Many individuals also have green patches on their necks. The underside including the inside of the arms and legs is dark gray to black with conspicuous orange to red spots, which sometimes only take up a fifth of the area, but in extreme cases also the largest portion. Most of the time, the proportion of reddish spots is just under 50 percent. The dark areas are covered with many white dots. There are five types of glands in the skin, including venom and mucous glands. The density of the glands is greatest in the head area and decreases towards the end of the body. Red-bellied toads have a color change and can adapt their back color to light or dark backgrounds. The color change only takes place in the basic color, the dark spots do not change.
In contrast to the yellow-bellied toad, the innermost fingers and toes as well as the tips of the limbs are not spotted in color. The drawing pattern on the abdomen is individual like a fingerprint. When threatened, the fire-bellied toad forms a hollow back and bends its arms and legs upwards, so that the red coloring of the underside is partially visible. This so-called Kahn position or unkenreflex to foes as a warning signal serve ( "Caution, toxic / inedible!").
Calls and call activity
Calls
The mating calls of the males represent sounds that consist of a basic frequency and up to six overtones. Because of this harmonic frequency structure, the calls are echoing to the human ear. With a 42-millimeter-tall male and a water temperature of 16 degrees Celsius, the basic frequency of the calls is on average 480 Hertz and the duration is 380 milliseconds. The lower call threshold is 13 to 14 degrees water temperature, the upper 33 to 34 degrees. Since the toads are cold-blooded, the calls are subject to the influence of temperature. When the water temperature rises, the number of calls per minute increases and rises from around 11 calls per minute at 13 degrees to around 34 calls per minute at 33 degrees. In addition, the higher the water temperature, the higher the pitch, while the duration of the calls decreases. The body size also has an influence on the calls. As the body length increases, the call duration increases while the pitch decreases. The repetition rate of the calls is independent of the height and therefore the age of the male. The calls are sometimes compared to those of the scops owl, the pygmy owl or the little bittern.
The hybridization of female red-bellied toad with male yellow-bellied toad was experimentally successful. At the age of 12 months, the male offspring were 28–34 millimeters in length, and the application of chorionic gonadotropin caused them to shout continuously. All important call characteristics, such as the repetition rate of calls, call duration, interval between calls, pitch and change in calls under the influence of the water temperature, are intermediate, as is the external coloration of the males and the size of their throat sacs.
As further call types with specific functions, male red-bellied toads have two calls for release and one call for brackets. The males make these calls when they are not inflated, so they are quiet.
Reputation formation
The mechanism with which the males generate their mating calls differs from that of the "modern" frogs ( Neobatrachia ) such as toads , frogs or tree frogs . Only the males lying on the water or partially submerged fill their lungs with air by pumping movements of the bottom of the throat. This lifts the males out of the water and ends up lying on the surface of the water with their bodies inflated. Some of the air in the lungs then flows back into the throat bladders and also makes them stand out. The calls are made by forcing air from the larynx through the larynx into the lungs. The lungs of the red-bellied toads thus represent functional sound bladders. The return flow of air into the throat bladders is voiceless. This call mechanism is also developed in the yellow-bellied toad. In the case of amphibians of other genera, on the other hand, the calls are formed when the air flows from the lungs into the sound sacs. Since in the toads the sound-generating air flow corresponds to the inhalation, whereas in the other amphibians it corresponds to the exhalation, a distinction is made between the inspiratory call formation of the toads and the expiratory call formation of the other amphibians.
Call behavior
Calling red-bellied toads are distributed irregularly on the surface of the water and keep a minimum distance of 1 to 1.5 meters. The males sometimes keep the chosen places for hours, they call continuously with only occasional short pauses. Calling males show territorial behavior. If a male approaches a calling toad within 50 centimeters or less, it will be attacked.
Annual and daily course of call activity
During the course of the year, the red-bellied toads show calling activity between April and July, which is divided into two or three clearly separated calling periods. These are usually initiated by rainfall.
The daily course of call activity is primarily determined by the water temperature. Since it is subject to a daily change that takes place differently with the seasons, three different diurnal courses of call activity can be seen in the fire-bellied toad. During the first call period in April or May, the water temperature in the morning is below the lower call threshold, rises during the day and falls again below the lower call threshold in the evening. On these days, the males mainly call during the day and fall silent in the evening when the lower call threshold is reached. The second form of call activity is given when the solar radiation is strong, which means that the upper call threshold is exceeded and the water temperature only falls below the lower call threshold at night. The toads have two calling phases, a first short one in the morning when the water temperature rises from the lower to the upper calling threshold, and a second, relatively long in the evening when the water temperature drops from the upper to the lower calling threshold. The third form of calling occurs on days with very high temperatures. The water temperature already exceeds the upper call threshold in the morning and only falls below it in the evening. On these days, the toads call in the evening and at night, around three or four o'clock they finally stop calling despite the favorable water temperature.
Shouts and hormones
Outside the natural call time, the application of chorionic gonadotropin, a hormone obtained from the blood serum of pregnant mares (PMSG = Pregnant Mare Serum Gonadotropin), triggers call activity in male toads. The biological effect of the hormone corresponds to that of a hormone of the anterior pituitary gland. If at least 250 international units of PMSG are injected, males will begin calling after 8 to 10 hours. They make mating and rescue calls and try to clasp other toads. The experimentally triggered calls do not differ from the normal calls. Call activity lasts up to three months and, like the toads in natural habitats, is divided into up to four call periods. In castrated males, PMSG has no effect, the cerebral call center is activated in conjunction with testosterone.
Spawn and larvae
A female produces several spawning clumps of up to 30 eggs each, for a total of up to 300 eggs per season. Their jelly shells have a diameter of five to eight millimeters per egg. They are attached to plants in shallow water. The larvae ( tadpoles ) are up to 55 millimeters long. Your upper fin edge is high and reaches down to the front third of the back; the tail reaches about one and a half times the length of the head and torso. The mouth area is almost triangular (oval in yellow-bellied toad larvae); two light stripes running lengthways along the body are characteristic.
distribution and habitat
The distribution area is concentrated in Eastern and Central Europe (= continental biogeographical region); To the northwest it extends to southern Sweden, Denmark, Ostholstein and northeast Lower Saxony , and to the south to Bulgaria. The main distribution areas within Germany are in Brandenburg and Mecklenburg-Western Pomerania . The fire-bellied toad has suffered severe population losses at its north-western limit of distribution. In Lower Saxony, for example, the latest evidence is now limited to the Elbe valley. The highest location in the entire area is 730 m above sea level in western Bohemia . Common occurrences with the yellow-bellied toad are excluded in many regions, among other things because of the different habitat requirements - exceptions are, for example, the east of Austria (e.g. Burgenland ), the Czech Republic and Romania.
Preferred biotopes are sunny, vegetation-rich, fish-free shallow waters with strong seasonal water level dynamics (seasonal floods) such as the Brandenburg Reichardtsluch ; these are populated from spring to autumn. In the Pleistocene the northeast German plain called form Sölle typical habitats. In September / October the return migration to the winter quarters takes place over distances of up to one kilometer. Wintering places are mainly woody trees with dead wood and leaves and occasionally piles of stone piles . The success of reproduction is subject to strong annual fluctuations, depending on temperature and precipitation.
food
The larvae feed mainly on organic growth (algae, bacteria) on plant stems and stones in the water. Developed toads only consume live animal food (for example insects), which they mainly catch in or near the water. Ukrainian red-bellied toads, for example, feed 50 percent on mosquitoes and their larvae and 20 percent on beetles.
The suitability of a body of water as a summer habitat for toads depends crucially on the type and extent of its organic production, which is why spawning grounds and summer habitats are not always identical. Toads therefore commute (mostly at night) between different bodies of water.
Danger
The fire-bellied toad is primarily endangered by the loss of habitat as a result of river straightening and dyke construction as well as extensive surface drainage. Direct destruction of water through backfilling also affects the animals, as does intensive agriculture and islanding , i.e. fragmentation of habitats, for example through roads. The species is mostly endangered on the western and north-western boundary of the area. The IUCN International Red List, on the other hand, classifies them as least concern , i.e. not endangered. The reason for this is, among other things, the still very good stock situation in Eastern and Southeastern Europe.
Legal protection status (selection)
- Fauna-Flora-Habitat-Guideline (FFH-RL): Appendices II and IV (special protection areas are to be designated / species to be strictly protected)
- Federal Nature Conservation Act (BNatSchG): strictly protected
National Red List classifications (selection)
- Red List Federal Republic of Germany: 2 - highly endangered
- Red list of Austria: VU (corresponds to: endangered)
- Red list of Switzerland: (this species does not appear here)
literature
- Antonia Cabela, Heinz Grillitsch, Franz Tiedemann: Bombina bombina (Linnaeus, 1761) fire-bellied toad, lowland toad. In: Atlas on the distribution and ecology of amphibians and reptiles in Austria: Evaluation of the herpetofaunistic database of the herpetological collection of the Natural History Museum in Vienna. Federal Environment Agency, Vienna 2001, pp. 256–269.
- Andreas Nöllert, Christel Nöllert: The amphibians of Europe. Franckh-Kosmos, Stuttgart 1992, ISBN 3-440-06340-2 .
- Hans-Joachim Obert: Studies on the hormonal control of calling and mating activity in the red and yellow-bellied toad Bombina bombina (L.) and Bombina v. variegata (L.). In: Zoologische Jahrbücher, Physiologie, Volume 77, 1973, pp. 166-198.
- Ernst Schmid: The call apparatus of the red and yellow-bellied toad and the midwife toad Bombina bombina (L.), Bombina v. variegata (L.), Alytes o. obstetricans (Laur.) (Anura, Discoglossidae). In: Zoologische Jahrbücher, Anatomie, Volume 98, 1977, pp. 171-180.
- Hans Schneider: The effect of local heating on the calls of the fire-bellied toad, Bombina bombina (L.). In: Behavioral Processes, Vol. 1, 1976, pp. 135-144.
- Hans Schneider: Bioacoustics of the Froschlurche - native and related species. With audio CD. In: Supplement of the journal for field herpetology. 6, Laurenti Verlag, Bielefeld 2005, ISBN 3-933066-23-9 .
- Uwe Zuppke, Marcel Seyring: fire- bellied toad - Bombina bombina (Linnaeus, 1761). In: Reports of the State Office for Environmental Protection Saxony-Anhalt. 4, 2015, pp. 185-206.
Individual evidence
- ↑ Hans-Joachim Obert, Hans Schneider: The glands in the skin of the fire-bellied toad (Bombina bombina (L.); Discoglossidae, Anura): type, number, size and distribution under natural and experimental conditions. Journal for microscopic-anatomical research, Leipzig, Volume 92, 1978, pp. 241-272.
- ↑ a b c d e f Klaus Lörcher: Comparative bio-acoustic studies on the red and yellow bellied toad, Bombina bombina (L.) and Bombina v. variegata (L.). Oecologia (Berlin) Volume 3, 1969, pp. 84-125.
- ↑ Hans Schneider: Bioacoustics of the Froschlurche - native and related species. With audio CD. Supplement to the Zeitschrift für Feldherpetologie 6. Laurenti Verlag, Bielefeld 2005. ISBN 3-933066-23-9
- ↑ a b Hans-Joachim Obert: Studies on the hormonal control of the calling and mating activity of the red and yellow bellied toad Bombina bombina (L.) and Bombina variegata (L.). Zoological Yearbooks, Physiology Department, Volume 77, 1973, pp. 166-198.
- ↑ Hans Schneider, Helga Eichelberg: The mating call of hybrids of the fire-bellied toad and yellow-bellied toad (Bombina bombina (L.), Bombina v. Variegata (L.), Discoglossidae, Anura). In: Oecologia (Berlin), Volume 16, 1974, pp. 61-71.
- ^ Hans Schneider and Institute for Scientific Film: Bombina bombina (Discoglossidae) - calls. Film E 2649 of the Institute for Scientific Film (IWF) Göttingen 1981. Publication by Hans Schneider, Publications on Scientific Films, Biology Section, Series 15, No. 17 / E 2649 (1982), 10 pages.
- ↑ a b c European fire-bellied toad (Bombina bombina). (PDF) WWF Germany , accessed on June 30, 2016 .
- ^ IUCN 2010. IUCN Red List of Threatened Species. Version 2010.4. Bombina bombina
- ↑ Red-bellied toad at www.wisia.de
- ↑ Federal Agency for Nature Conservation (ed.): Red list of endangered animals, plants and fungi in Germany 1: Vertebrates. Landwirtschaftsverlag, Münster 2009, ISBN 978-3784350332
- ↑ Online overview at www.amphibienschutz.de
