Mallorcan midwife toad
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Order: Anura
Family: Alytidae
The Alytidae family comprises 11 species in two genera, which are commonly referred to as the “midwife toads” (genus: Alytes) and the “painted frogs” (genus: Discoglossus). Overall, this family is now named after the midwife toads, in reference to the extraordinary level of parental care by the males in the family’s component genus Alytes – they carry strings of eggs wrapped around their hind legs for a month or more, keeping them protected and moist until they are ready to hatch. The Alytidae are an ancient family found throughout Europe, the Middle East and northwestern Africa. They diverged from all other amphibians about 210 millions years ago at the end of the Triassic period, which is around the same time that the first primitive mammals started to appear. The midwife toad family therefore evolved at the feet of some of the earliest dinosaurs, and survived the dinosaur’s demise nearly 150 million years later.
The midwife toad family are present in a small sub group of the Anura or “frogs and toads” which contains all of the most ancient families. This sub group (also called the Archaeobatrachia) comprises less than 7% of all of the frogs and toads, including some of the most evolutionarily distinct amphibian species. The family name of the midwife toads was formerly Dicroglossidae or “disc-tongued frogs” because, unlike the relatively slender tongues of many amphibians, midwife toads and painted toads possess a round and flattened tongue. Aside from their highly unusual breeding behaviour, midwife toads are also known to have a powerful defense mechanism against potential predators. They have warts on their back that produce a strong-smelling toxin when the toad is threatened, and a midwife toad’s poison can kill an adder (a venomous snake) in a matter of hours. Within the family Alytidae, the midwife toads diverged from their closest relatives, the painted frogs, about 155 million years ago, which is about 5 million years before the first birds started to appear in the fossil record. Midwife toads are therefore more different from their closest relatives than kangaroos are to elephants, as they started to evolve independently about 10 million years before the common ancestor of these two mammal groups. There are just 5 species of midwife toad surviving today, all in Europe.
The Mallorcan midwife toad (Alytes muletensis) was first identified from fossils that formed during the Pleistocene (a period extending from 5.3 to 1.6 million years ago) in mainland Europe. This species was originally assigned to a new genus of extinct amphibians called Baleaphryne, and was believed to have gone extinct over 2,000 years ago. Itwas assumed have been wiped out following the colonisation of Mallorca by man in about 4000BC. However, the Mallorcan midwife toad was discovered to be inhabiting the inaccessible limestone gorges of Mallorca’s Sierra de Tramuntana in 1977, and was transferred from the now defunct genus Baleaphryne and placed with the other midwife toads in the Alytes genus. The Mallorcan midwife toad is therefore a “living fossil”.
The midwife toad family are present in a small sub group of the Anura or “frogs and toads” which contains all of the most ancient families. This sub group (also called the Archaeobatrachia) comprises less than 7% of all of the frogs and toads, including some of the most evolutionarily distinct amphibian species. The family name of the midwife toads was formerly Dicroglossidae or “disc-tongued frogs” because, unlike the relatively slender tongues of many amphibians, midwife toads and painted toads possess a round and flattened tongue. Aside from their highly unusual breeding behaviour, midwife toads are also known to have a powerful defense mechanism against potential predators. They have warts on their back that produce a strong-smelling toxin when the toad is threatened, and a midwife toad’s poison can kill an adder (a venomous snake) in a matter of hours. Within the family Alytidae, the midwife toads diverged from their closest relatives, the painted frogs, about 155 million years ago, which is about 5 million years before the first birds started to appear in the fossil record. Midwife toads are therefore more different from their closest relatives than kangaroos are to elephants, as they started to evolve independently about 10 million years before the common ancestor of these two mammal groups. There are just 5 species of midwife toad surviving today, all in Europe.
The Mallorcan midwife toad (Alytes muletensis) was first identified from fossils that formed during the Pleistocene (a period extending from 5.3 to 1.6 million years ago) in mainland Europe. This species was originally assigned to a new genus of extinct amphibians called Baleaphryne, and was believed to have gone extinct over 2,000 years ago. Itwas assumed have been wiped out following the colonisation of Mallorca by man in about 4000BC. However, the Mallorcan midwife toad was discovered to be inhabiting the inaccessible limestone gorges of Mallorca’s Sierra de Tramuntana in 1977, and was transferred from the now defunct genus Baleaphryne and placed with the other midwife toads in the Alytes genus. The Mallorcan midwife toad is therefore a “living fossil”.
The Mallorcan midwife toad is a small frog with relatively large head. Smaller than their mainland relatives, adult females (measuring 38 mm in length) are slightly larger than adult males, which reach a length of up to 34.7 mm. The eyes are large and have a vertical slit-shaped pupil. The limbs are relatively long, as are the fingers and toes, which are unwebbed. The skin is fairly smooth and shiny, although some larger warts are present along the sides of the back. The coloration of this species is very variable. Usually the background colour is greenish-gold, with dark green to black spots of variable size and shape across the back. There is often a black triangle present on the head between the eyes. The underside is white and smoother than the back. Apart from a slight difference in size, males and females are difficult to distinguish from their appearance.
Midwife toads are nocturnal (or night active) ground dwellers, and are often found in groups under rocks, fallen logs or in the ground. The Mallorcan midwife toad was only known from fossils until 1977, and escaped earlier detection because of it lives in small colonies within the narrow, deep crevices of limestone cliffs in a small area of northern Mallorca. This species is adapted to life in harsh, dry conditions and have evolved a highly flattened body, which enables these toads to hide within the narrowest crevices in its rocky habitat. They have been described as secretive toads that live mainly beneath rocks and in borrows, from which the males call in a high-pitched peep. Mating and egg laying occurs on land, principally between the months May and June. Exact details of the Mallorcan midwife toad’s life history in the wild remain unknown, but much information can be inferred from studies of its close relatives in mainland Europe. However, it is understood that this species does not hibernate, and that intense competition for males occurs amongst females, who grapple with each other over mates. Reproductive success in this species seems to increase with elevation, as the number of potential predators deceases.
Midwife toads display remarkable and very unusual breeding behaviour, which is common to all member of the genus Alytes. Male midwife toads usually live in a hole in the ground that is reasonably damp and within a short distance of a water source. They make short, peeping calls to alert females to their presence. When a gravid (egg-bearing) female come to visit, the males embraces her firmly until she starts to produce her eggs. Female Mallorcan midwife toads produce clutches of 7 to 12 eggs, which occur in a long string like all species of midwife toad. The eggs in this species are larger than those of other midwife toads, but also fewer in number. The eggs measure 5.4 to 7mm in diameter and, as they emerge, the male releases his grip of the female and crouches over the eggs releasing his sperm to fertilise them. After about a quarter of an hour, the male then slides forward on top of the female, reaches around her throat and, through a complicated set of movements, wraps the egg strings around his hind legs. When the male succeeds in wrapping the egg string securely around his hind legs, the female departs, leaving the male to care for the eggs until they hatch.
Male Mallorcan midwife toads may add eggs strings from other females to their collection as the breeding season continues. They may keep the eggs wrapped around their hind legs for a month or more, protecting them from predation and preventing their desiccation. Although the males shelter in damp refuges which keep the eggs moist, they will also occasionally make trips to pools of water to moisten the eggs further. The male then hides in a dark, damp burrow until the tadpoles are ready to hatch. The eggs and tadpoles are light sensitive. Increasing movement of the tadpoles inside the eggs stimulates the male to briefly move into water. The only water available in this species’ limestone cliff habitat is found in small, rain-filled puddles on ledges, or in small streams that persist as pools in summer. A few populations also occur by man-made water sources, such as cattle troughs and rain tanks, in open mountainous country within the river basins of nearby limestone canyon living populations. Depositing the eggs in water causes their spontaneous hatching, and the tadpoles continue the remainder of their development in water.
The first tadpoles hatch in May, measuring around 18 mm in length. Tadpoles undergo metamorphosis any time from late June to September, and some may even over-winter as tadpoles and metamorphose the following summer, remaining in the tadpole phase for as long as a year. Mallorcan midwife toad tadpoles grow very large (up to 76 mm in length in a few weeks) and little further growth occurs after metamorphosis into the adult form. The tadpoles spend much oft heir time hanging tail down from the surface of the water, but dive down immediately if disturbed.
Both male and female Mallorcan midwife toads call to locate each other. Studies have indicated that this species does not only use calls during the mating season, but also throoughout the years to serve other purposes. This species is not especially territorial, so when one adult is heard calling there are usually numerous others close by. It is therefore possible that calling acts as a grouping mechanism to encourage aggregation in an area where the availbility of suitable refuges is scarece. Grouping together with other individuals may create a damper environment, or may reflect a “selfish herd” strategy, whereby the danger of predation to each individual is reduced in a crowd. Also, newly metamorphosed toadlets have been observed moving towards the calls of adults, as they move from the pools in which they lived their lives as tadpoles, to the rocky crevices where they will mature. Groups of Mallorcan midwife toads are highly dispersed within their habitat, and as such the vocalisations of calling toads probably serve as a major cue to toadlets searching for new habitat and other members of their species. Calling therefore seems to have an important social cohesion function that is not necessarily related to breeding.
Male Mallorcan midwife toads may add eggs strings from other females to their collection as the breeding season continues. They may keep the eggs wrapped around their hind legs for a month or more, protecting them from predation and preventing their desiccation. Although the males shelter in damp refuges which keep the eggs moist, they will also occasionally make trips to pools of water to moisten the eggs further. The male then hides in a dark, damp burrow until the tadpoles are ready to hatch. The eggs and tadpoles are light sensitive. Increasing movement of the tadpoles inside the eggs stimulates the male to briefly move into water. The only water available in this species’ limestone cliff habitat is found in small, rain-filled puddles on ledges, or in small streams that persist as pools in summer. A few populations also occur by man-made water sources, such as cattle troughs and rain tanks, in open mountainous country within the river basins of nearby limestone canyon living populations. Depositing the eggs in water causes their spontaneous hatching, and the tadpoles continue the remainder of their development in water.
The first tadpoles hatch in May, measuring around 18 mm in length. Tadpoles undergo metamorphosis any time from late June to September, and some may even over-winter as tadpoles and metamorphose the following summer, remaining in the tadpole phase for as long as a year. Mallorcan midwife toad tadpoles grow very large (up to 76 mm in length in a few weeks) and little further growth occurs after metamorphosis into the adult form. The tadpoles spend much oft heir time hanging tail down from the surface of the water, but dive down immediately if disturbed.
Both male and female Mallorcan midwife toads call to locate each other. Studies have indicated that this species does not only use calls during the mating season, but also throoughout the years to serve other purposes. This species is not especially territorial, so when one adult is heard calling there are usually numerous others close by. It is therefore possible that calling acts as a grouping mechanism to encourage aggregation in an area where the availbility of suitable refuges is scarece. Grouping together with other individuals may create a damper environment, or may reflect a “selfish herd” strategy, whereby the danger of predation to each individual is reduced in a crowd. Also, newly metamorphosed toadlets have been observed moving towards the calls of adults, as they move from the pools in which they lived their lives as tadpoles, to the rocky crevices where they will mature. Groups of Mallorcan midwife toads are highly dispersed within their habitat, and as such the vocalisations of calling toads probably serve as a major cue to toadlets searching for new habitat and other members of their species. Calling therefore seems to have an important social cohesion function that is not necessarily related to breeding.
The Mallorcan midwife toad is endemic to the island of Mallorca off the eastern coast of Spain. This species inhabits inaccessible brooks in limestone gorges or canyons in the northern Mallorca, and hides under stones and in crevices in groups of up to 5 individuals. Its preferred streams are small and deeply carved into the limestone mountains. It is present at greater densities on steep slopes and higher elevations of its altitudinal range, where predators may be less common. The species is found in only ten brooks (torrentes) in the Sierra de Tramuntana. The area receives an annual rainfall of 1000 to 2000 mm and water temperatures range from 9ºC-22ºC. This species does not tolerate serious habitat degradation, although a few populations occur by man-made water sources, such as cattle troughs, containers and rain tanks, in open mountainous country within the river basins of nearby canyon living populations.
This species is restricted to the Sierra de Tramuntana of northern Mallorca in the Balearic Islands, Spain. The present altitudinal range is from 10–850 metres above sea level. The area of occurrence is 180 km sq., although the area of occupancy is less than 10 km sq.. However, this is slowly increasing as a result of intensive conservation action.
The population is approximately 500 to 1,500 adult pairs divided between about 25 (mostly isolated) populations. The total population is slowly increasing following co-ordinated recovery efforts involving a captive breeding programme at Jersey Zoo. Prior to these conservation actions, a long period of decline had almost rendered this species extinct. The current increase, which probably started around the time that the first re-introductions were made in 1989, has been made maintained even during years of drought, notably in 1999-2000. The population trends are monitored through annual tadpole counts, with the counts for 2004 (over 30,000 tadpoles) being the highest on record. The increase in numbers in established populations is not dependent upon continued re-introductions. However, it is unlikely that new populations would become established without re-introductions. It is estimated that a quarter of the animals now present on the island came from captive toads. It is possible that the range of the Mallorcan midwife toad may have doubled across the Sierra de Tramuntana, and plans are afoot to create protected regions where more toads can be reintroduced.
The overall wild population of this species is thought to be increasing by the IUCN Red List of Threatened Species.
The Mallorcan midwife toad is listed as Vulnerable in the IUCN Red List of Threatened Species because it is known from fewer than five locations, and its area of occupancy is less than 20 km sq..
The major threats to this species is predation of both adults and tadpoles by the non-native viperine watersnake (Natrix maura), which was introduced by the Romans. Additionally, the introduction of Perez's green frog (Rana perezi) has created competition for food and space in habitats occupied, or formerly occupied, by the Mallorcan midwife toad. Today, the Mallorcan midwife toad lives only in places that these non-native species cannot reach. Factors such as the development of tourism and human settlements have led to increased demand for water resources, and have resulted in the damming and canalisation of streams, placing pressure on northern mountain water resources. These threats are not likely to decrease, and so the current recovery programme needs to be continued more or less indefinitely. One isolated re-introduced population was impacted by an unidentified non-fungal disease in 2002 which killed some tadpoles. This disease did not recur in 2003 and 2004. A further threat arises from the small size of the remaining population, which places the species at risk of extinction from chance catastrophic events, such as virulent disease and extreme weather events. The fungal disease chytridiomycosis may also be a sinister threat to the future of these frogs, since it is affecting amphibian populations globally and has been found in closely related midwife toads in mainland Europe.
The Mallorcan midwife toad is protected by sub-national and national legislation, and its habitat was suggested as a Biogenetic Reserve to the council of Europe. State and regional laws have forbidden the capture, keeping or killing of this species since 1980. It is listed on Appendix II of the Berne Convention, and on Annexes II and IV of the EU Natural Habitats Directive. It is also registered in the national and sub-national Red Data Books. This species is present in the protected areas of the Tramuntana mountains. A conservation project is underway for the Mallorcan midwife in cooperation between the Balearic Government, Mallorcan Consellaria de Medi Ambient, Durrell Wildlife Conservation Trust, the Durrell Institute of Conservation and Ecology at Kent University, and Barcelona Zoo. This species breeds well in captivity and reintroductions have been taking place since 1988, with several breeding populations already successfully established as a result. At least 10 populations have been successfully reintroduced. Re-introductions of animals from the Jersey Wildlife Preservation Trust stopped in 2002, but a new captive-breeding facility now exists on Mallorca, and re-introductions are expected to resume. However, as a result of the recent discovery of diseases, a recommendation was been made in 2004 to the Balearic Government to halt re-introduction programme. Annual surveys are taking place and a reserve has been proposed to help protect the species. The number of suitable sites for reintroduction is limited, so work is currently focusing on the creation of new pools. A new recovery programme for the species is being developed. A systematic programme is in place to remove the non-native viperine watersnake from the range of this species.
There are many conservation actions already underway for this species, and it is vital that these continue to ensure a long-term further for the Mallorcan midwife toad. Population and disease monitoring should be prioritised to ensure that any declines are swiftly detected, and that action be taken to mitigate the significant threat of disease to wild populations should further pathogens be discovered in these toads.
Trent is a specialist in amphibian disease and ecology
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Seigel, R.A. and Dodd, C.K. 2002. Translocations of Amphibians: Proven Management Method or Experimental Technique? Conservation Biology 16(2): 552-554.
Roca, V., García, G., Carbonell, E., Sánchez-Acedo, C. and Del Cacho, E. 1998. Parasites and conservation of Alytes muletensis (Sanchiz et Adrover, 1977) (Anura: Discoglossidae). Revista Española de Herpetología 12: 91-95.
Roelants, K., Gower, D. J., Wilkinson, M., Loader, S. P., Biju, S. D., Guillaume, K., Moiau, L. and Bossuyt, F. 2007. Global patterns of diversification in the history of modern amphibians. Proceedings of the National Academy of Sciences 104: 887-892.
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Schley, L., Griffiths, R.A. and Román, A. 1998. Activity patterns and microhabitat selection of Mallorcan midwife toad (Alytes muletensis) tadpoles in natural torrent pools. Amphibia-Reptilia 19(2): 143-151.
Serra, J.M., Griffiths, R., Bosch, J., Beebee, T., Schmidt, B., Tejedo, M., Lizana, M., Martínez-Solano, I., Salvador, A., García-París, M., Gil, E.R. & Arntzen, J.W. 2004. Alytes muletensis. In: IUCN 2006. 2006 IUCN Red List of Threatened Species.. Downloaded on 06 July 2007.
AmphibiaWeb: Information on amphibian biology and conservation [web application]. 2006. Berkeley, California: AmphibiaWeb. Available:
Arnold, E.N. 2003. Reptiles and amphibians of Europe. Princeton University Press, Princeton and Oxford.
Arntzen, J.W. and García-París, M. 1995. Morphological and allozyme studies of midwife toads (Genus Alytes), including the description of two new taxa from Spain. Contributions to Zoology 65(1): 5-34.
Behler, J.L. and Behler, D.A. 2005. Frogs: A Chorus of Colors. Sterling Publishing, NY, U.S.A.
Buley, K.R. and Garcia, G. 1997. The recovery programme for the Mallorcan midwife toad Alytes muletensis: An update. Dodo. J. Wildl. Preserv. Trusts 33: 80-90.
Bush, S. 1996. The reproductive behaviour of the Ferreret Alytes muletensis. Boletín de la Asociación Herpetológica Española 7: 35-37.
Duellman, W. E. and Trueb, L. 1986. Biology of Amphibians. McGraw-Hill, New York.
Fromhage, L., Vences, M. and Veith, M. 2004. Testing alternative vicariance scenarios in Western Mediterranean discoglossid frogs. Molecular Phylogenetics and Evolution 31(1): 308-322.
Frost, D. R., Grant, T., Faivovich, J., Bain, R.H., Haas, A., Haddad, C. F. B., De Sá, R.O., Channing, A., Wilkinson, M., Donnellan, S.C., Raxworthy, C.J., Campbell, J.A., Blotto, B.L., Moler, P., Drewes, R.C., Nussbaum, R.A., Lynch, J.D., Green, D.M., and Wheeler, W.C. 2006. The Amphibian Tree of Life. Bulletin of the American Museum of Natural History 297: 1-370.
Frost, Darrel R. 2006. Amphibian Species of the World: an Online Reference. Version 4 (17 August 2006). Electronic Database accessible at:
Gasc, J.-P. (ed.) 1997. Atlas of Amphibians and Reptiles in Europe. Societas Europea Herpetologica & Museum National d'Histoire Naturelle, Paris.
Groombridge, B. (ed.) 1994. 1994 IUCN Red List of Threatened Animals. IUCN, Gland, Switzerland.
Halliday, T. 1992. United Kingdom Aids Recovery. FrogLog 2: 3.
IUCN Conservation Monitoring Centre. 1988. 1988 IUCN Red List of Threatened Animals. IUCN, Gland, Switzerland and Cambridge, UK.
IUCN, Conservation International and NatureServe. 2006. Global Amphibian Assessment.
IUCN. 1990. 1990 IUCN Red List of Threatened Animals. IUCN, Gland, Switzerland and Cambridge, UK.
Lea, J., Dyson, M. and Halliday, T. 2002. Phonotaxis to advertisement calls by midwife toads (Alytes muletensis) is not necessarily related to mating. Amphibia-Reptilia 23: 151-159.
Lea, J., Dyson, M. and Halliday, T. 2002. The effects of cohort structure and density on larval growth and development in Alytes muletensis: Implications for conservation. Herpetological Journal 12(4): 155-161.
Martínez-Solano, I., Gonçalves, H.A., Arntzen, J.W. and García-París, M. 2004. Phylogenetic relationships and biogeography of midwife toads (Discoglossidae: Alytes). Journal of Biogeography 31(4): 603-618.
Mattison, C. 1987. Frogs and toads of the world. Blandford Press, U.K.
Mejias, R. and Amengual, J. 2000. Libro rojo de los vertebrados de las Baleares (2ª ed.). Govern de les Illes Balears, Conselleria de Medi Ambient, Palma de Mallorca.
Moore, R.D., Griffiths, R.A. and Román, A. 2004. Distribution of the Mallorcan midwife toad (Alytes muletensis) in relation to landscape topography and introduced predators. Biological Conservation 116: 327-332.
Obst, F.J., Richter, K. and Jacob, U. 1984. The Completely Illustrated Atlas of Reptiles and Amphibians for the Terrarium. T.F.H. Publication Inc., N.J., U.S.A.
Pleguezuelos, J.M. 1997. Distribucion y Biogeografia de los Anfibios y Reptiles en España y Portugal. Asociacion Herpetologica Española, Las Palmas de Gran Canarias.
Pleguezuelos, J.M., Márquez, R. and Lizana, M. 2002. Atlas y Libro Rojo de los Anfibios y Reptiles de España. Dirección General de la Conservación de la naturaleza-Associación Herpetológica Española, Madrid.
Seigel, R.A. and Dodd, C.K. 2002. Translocations of Amphibians: Proven Management Method or Experimental Technique? Conservation Biology 16(2): 552-554.
Roca, V., García, G., Carbonell, E., Sánchez-Acedo, C. and Del Cacho, E. 1998. Parasites and conservation of Alytes muletensis (Sanchiz et Adrover, 1977) (Anura: Discoglossidae). Revista Española de Herpetología 12: 91-95.
Roelants, K., Gower, D. J., Wilkinson, M., Loader, S. P., Biju, S. D., Guillaume, K., Moiau, L. and Bossuyt, F. 2007. Global patterns of diversification in the history of modern amphibians. Proceedings of the National Academy of Sciences 104: 887-892.
Román, A. and Mayol, J. 1997. La recuperación del ferreret, Alytes muletensis. In: Documents Tècnics de Conservació, II(1). Consellería de Medi Ambient, Ordenació del Territori i Litoral, 80 pp. Govern Balear, Palma de Mallorca.
Schley, L., Griffiths, R.A. and Román, A. 1998. Activity patterns and microhabitat selection of Mallorcan midwife toad (Alytes muletensis) tadpoles in natural torrent pools. Amphibia-Reptilia 19(2): 143-151.
Serra, J.M., Griffiths, R., Bosch, J., Beebee, T., Schmidt, B., Tejedo, M., Lizana, M., Martínez-Solano, I., Salvador, A., García-París, M., Gil, E.R. & Arntzen, J.W. 2004. Alytes muletensis. In: IUCN 2006. 2006 IUCN Red List of Threatened Species.
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