Small stocky frog with relatively large head. Adults of both sexes obtain a
snout-vent length of about 55 mm. The eyes are large and have a vertical
slit-shaped pupil. Parotid glands are small, and the tympanum is mostly
visible. The skin is warty, and a row of large, often reddish warts
extends from the tympanum to the loin area. Other large gland complexes
are present on the underarms and the ankles. There are three metacarpal
tubercles. The coloration can vary from small black dots, brown dots to
olive or green spots. The underside is a dirty white, and the throat and
the chest are often spotted with gray (Noellert and Noellert 1992).
Males are somewhat smaller than females. Other features that distinguish males
and females are: distance between nostrils, distance between the anterior
end of the middle metacarpal tubercle and the tip of the third finger, and
the distance from the elbow to the third finger tip. These variables should
be corrected for the size of the animal (Bosch and Marquez 1996).
Distribution and Habitat
Country distribution from AmphibiaWeb's database: Belgium, France, Germany, Italy, Luxembourg, Netherlands, Portugal, Spain, Switzerland. Introduced: United Kingdom.
This animal occurs in eight European countries: Portugal, Spain, France, Belgium, The
Netherlands, Luxembourg, Germany and Switzerland. There are three European
subspecies. A. o. obstetricans occurs north of the Pyrenees,
A. o. almogavarii between the Pyrenees and the Ebro river and A. o. boscai south of the Ebro river. Another subspecies, A. o. maurus Pasteur & Bons, 1962, is endemic in the Rif mountains in Morocco. The species is present practically throughout France, with the exception of the higher part of the Alps. A. obstetricans shows a very clearly marked distribution limit between the mountainous and hilly regions of Central Europe which are inhabited, and the large plain to the North Sea, where the species is absent. For this reason, it cannot be found along the coast of Belgium, and in most part of the Netherlands (only in the hilly South Limburg). The northernmost population is found south of Hannover, in lower Saxony, the easternmost population in Northern and Central Germany (hilly regions of Thüringen and Harz). In Southern Germany the species only occurs in Baden-Württemberg in the region of the Black Forest. Switzerland is inhabited mainly in the Jura, in the central plain up to the Rhine, and in some parts of the northern slope of the Alps, though here only
The water habitat varies greatly: not only all types of pools and ponds are
used, but also not too fast running creeks (mainly in Iberia) and rivers.
A. obstetricans prefers permanent waters, because larvae often over
winter in water. The land habitat is just as important as the breeding
sites: slopes, walls, embankments with many small stones, stone slabs or
sand, normally with sparse vegetation are preferred. Larger colonies are
observed in gravel or clay pits. Often the exposition is south, southwest
or southeast and well exposed to the sun. The microclimate in the hiding
places must be warm and humid.
In the Iberian Peninsula A. obstetricans occurs from the sea shore
(e.g. in Asturias and Basque Country) up to 1960 m (in Portugal) and 2400 m
in the Pyrenees. In the Alps, populations can be found up to 1670 m in the
Bernese Oberland. In Central Europe, most populations live t altitudes between
200 and 700 m, rarely below 200 m (Gasc 1997).
Life History, Abundance, Activity, and Special Behaviors
These frogs are well known for their male parental care behavior. The males attach the egg masses to their body and carry them until the eggs hatch, at this point the males release the tadpoles into bodies of water. The females can
produce up to four clutches of eggs per breeding season. Mating season varies
throughout the range. In Westfalen, Germany one can find males carrying eggs
between the end of March, and the beginning of August. Around the city of
La Coruña, males with clutches of eggs were observed from mid-February
until August. In mountain populations most males carry eggs well into
August. Although males call mainly by night, they are known to call from
their hiding places during the daytime. The call is a high-pitched, explosive,
musical "poo...poo…poo…", about one call every 1-3 sec, usually higher
and shorter than Bombina.
The female seeks out the male and presents herself to him. The male grabs
the female in the lumbar region. The male stimulates the females cloacal
region by scratching it with its toes. After about 35 minutes, the male
suddenly constricts the female's flanks. She extends her hind legs and
ejects an egg mass. The male then
releases his lumbar grip, takes an axillar hold and inseminates the eggs
with a quantity of liquid sperm mass. After 10-15 minutes, the male distends
the egg mass with his hind legs , plies them alternatingly to his body and
extends them again until the strings of eggs are wound around his ankles.
A male can copulate anew and carry up to three clutches around his legs
with a total of 150 eggs or more (Schleich 1996). Males keep the
egg mass moist by microhabitat choice, or by taking short baths. Larvae
hatch after 3 to 6 weeks. The males seek out small water bodies to discard
the egg strings with the hatching larvae. Upon hatching, the larvae are
about 15 mm and metamorphose the next year, when they have reached a maximum
length of 5 to 8 cm (Engelmann 1985).
Trends and Threats
Populations of this species are threatened, especially on the northern border
of its distribution. These populations suffer from the disturbance caused by the release of fish in their breeding waters (Noellert and Noellert 1992).
Populations along the northern border, e.g., in Limburg, eastern Germany,
in the Black Forest and western and central parts of the Swiss range, have
disappeared for no obvious reason. The disappearance is likely to be disease-related, as this species is susceptible to chytridiomycosis (Bosch et al. 2001). In 1997, 1998, and 1999, mass die-offs of post-metamorphic A. obstetricans occurred in Spain, and dead frogs were found to have chytrid infections (Bosch et al. 2001). Habitat loss is also a factor in the decline of this species; in addition to outright habitat destruction, changes affecting the microclimatic conditions (e.g., drainage) have had a negative impact on A. obstetricans (Gasc 1997).
Possible reasons for amphibian decline
General habitat alteration and loss
Drainage of habitat
Predators (natural or introduced)
Bosch, J. and Marquez, R. (1996). ''Discriminant functions for the sex identification in two midwife toads (Alytes obstetricans and A. cisternasii).'' Herpetological Journal, 6, 105-109.
Bosch, J., Martinez-Solano, I., and García-París, M. (2001). ''Evidence of a chytrid fungus infection involved in the decline of the common midwife toad (Alytes obstetricans) in protected areas of central Spain.'' Biological Conservation, 97(3), 331-337.
Engelmann, W.-E., Guenter, R., and Obst, F. J. (1985). Lurche und Kriechtiere Europas. Neumann Verlag, Leipzig.
Gasc, J.-P. (1997). Atlas of Amphibians and Reptiles in Europe. Societas Europaea Herpetologica, Bonn, Germany.
Nöllert, A. and Nöllert, C. (1992). Die Amphibien Europas. Franckh-Kosmos Verlags-GmbH and Company, Stuttgart.
Pennisi, E. (2009). ''The case of the midwife toad: fraud or epigenetics?'' Science, 325(5945), 1194-1195.
Schleich, H. H., Kastle, W., and Kabisch, K. (1996). Amphibians and Reptiles of North Africa. Koeltz Scientific Publishers, Koenigstein.
Stumpel-Rieks, S. E. (1992). Nomina Herpetofaunae Europaeae. AULA-Verlag, Wiesbaden.
Vargas, A. O. (2009). ''Did Paul Kammerer discover epigenetic inheritance? a modern look at the controversial midwife toad experiments.'' Journal of Experimental Zoology Part B (Molecular Development and Evolution), 312B, 667-678.
Wagner, G. P. (2009). ''Paul Kammerer’s midwife toads: about the reliability of experiments and our ability to make sense of them.'' Journal of Experimental Zoology Part B (Molecular Development and Evolution), 312B, 665-666.
Written by Arie van der Meijden (amphibia AT arievandermeijden.nl), Museum of Vertebrate Zoology, UC Berkeley
First submitted 1999-09-22
Edited by Vance Vredenburg, Kellie Whittaker (2010-01-18)
Species Account Citation: AmphibiaWeb 2010 Alytes obstetricans: Midwife toad <http://amphibiaweb.org/species/1522> University of California, Berkeley, CA, USA. Accessed Jan 23, 2020.
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Citation: AmphibiaWeb. 2020. <http://amphibiaweb.org> University of California, Berkeley, CA, USA. Accessed 23 Jan 2020.
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