Alytes obstetricans

Geographic Range

Common midwife toads occur in southern Belgium, most of France, western and north-central Germany, Luxembourg, the southeastern Netherlands, northern Portugal and Spain, and northwestern Switzerland; with at least one introduced population in the UK. Populations are reported to be declining and in some areas populations appear to be completely eradicated, such as in coastal Portugal (west of Lisbon). Populations are particularly fragmented in Spain and Portugal but common midwife toads are still common throughout many areas, particularly France.

• Biogeographic Regions
• palearctic palearctic
  • introduced introduced
  • native native

Habitat

Common midwife toads are primarily terrestrial, inhabiting a wide range of habitats such as temperate forests and semi-arid areas. They successfully reside in human-modified habitats, such as agricultural plots and urban areas (ex: Barcelona). This species prefers areas with slopes, walls, or embankments with sparse vegetation and many small stones. They are often found hiding in the crevices of these structures, under logs, or underground in pre-existing burrows of other animals, in order to prevent from drying out. Aquatic habitats are only required for breeding. There is a wide range of appropriate aquatic habitats for breeding from ponds to slow moving rivers, and occasionally gravel or clay pits. Permanent waters are preferred because larvae over-winter in water.

• Habitat Regions
• temperate temperate
• terrestrial terrestrial
• freshwater freshwater

• Terrestrial Biomes
• forest forest

• Aquatic Biomes
• lakes and ponds
• rivers and streams

• Other Habitat Features
• urban urban
• agricultural agricultural

Physical Description

Common midwife toads are not "true toads"; they are frogs with warty skin and stout toad-like bodies. Their fingers are short and un-webbed and they have long toes that are only webbed at the base. Their bodies are covered in reddish warts; the warts are particularly prevalent on the ankles, underarms, and in a line from the eardrum to the groin. Body coloration can be quite varied, ranging from pale to brown. The underside is an off-white color. The spots on the throat and chest can be many colors including black, brown, olive, green or grey. They have vertical slit-shaped pupils in their large eyes. The parotoid glands are small, with a mostly visible tympanum. Common midwife toads have three metacarpal tubercles. Males are smaller than females, growing to 42 mm in length, as opposed to females, which can grow to 50 mm.

• Other Physical Features
• ectothermic ectothermic
• heterothermic heterothermic
• bilateral symmetry bilateral symmetry

• Sexual Dimorphism
• female larger

Development

Eggs are carried on the male’s body until they hatch. Tadpoles are then deposited into small permanent bodies of water. Larvae are originally about 15 mm long and reach surprisingly large sizes. They metamorphose when they reach a length of 5 to 8 cm, which occurs after about a year. Sexual maturity occurs at 2 to 3 years of age for both males and females.

• Development - Life Cycle
• metamorphosis metamorphosis

Reproduction

Common midwife toads get their common name from their unique mating system. Males carry eggs on their bodies until the eggs hatch and then the males release the tadpoles into a body of fresh water (often permanent water because tadpoles must over-winter). Males call mainly at night about every 1 to 3 seconds with a high-pitched “poo…poo…” sound. Once a female locates a male and presents herself, the male will grab the female around her lumbar region and begin stimulating her cloaca with a scratching motion of his toes. The female will then expel an egg mass that is subsequently fertilized by the male’s ejection of a liquid sperm mass. Inseminated eggs are then wound around the male’s ankles.

• Mating System
• polygynandrous (promiscuous) polygynandrous (promiscuous)

Sexual maturity occurs at about 12 to 18 months. Mating seasons vary throughout the toad’s range and egg-carrying males can be found anytime between the end of March and the beginning of August. By carrying the eggs, male toads are able to keep them out of the water, where the eggs are in high danger of getting eaten. Males can carry about 150 eggs around their ankles during one breeding season, which is equivalent to about three clutches. Females can produce up to four clutches per breeding season. Males keep the eggs moist by choosing appropriate microhabitat and occasionally taking freshwater “baths.” After 3 to 6 weeks the eggs hatch and the tadpoles are deposited by the male into a small body of water.

• Key Reproductive Features
• iteroparous iteroparous
• seasonal breeding seasonal breeding
• gonochoric/gonochoristic/dioecious (sexes separate)
• fertilization fertilization
  • external external
• oviparous oviparous

After fertilization, males carry the eggs on their hind-legs until they hatch. After hatching, males carefully deposit the larvae into small, permanent bodies of water.

• Parental Investment
• male parental care male parental care
• pre-fertilization
  • provisioning
  • protecting
    • female
• pre-hatching/birth
  • provisioning
    • female
  • protecting
    • male

Lifespan/Longevity

Common midwife toads live up to eight years in the wild.

Behavior

Common midwife toads are highly terrestrial, only living in the water as tadpoles. They are also nocturnal and often hide in holes or under logs to prevent from drying out. If an individual can not find a pre-existing hole, it uses its forelimbs and head to dig its own burrow, then it uses a "push-up" like motion to pack soil over the head, creating a roof for the hole. Common midwife toads typically exit their burrows at dusk to forage for insects and other arthropods. Adults are able to terrestrially hibernate under frost-protected ground during winter months. During the breeding season, males call every night for several hours. Occasionally, males can be heard calling from their burrows during the day. Females tend to prefer males who call frequently. Females give a response call to the male of her choice, which is uncommon amongst other anurans . Competition between males during the breeding season is strictly vocal, with no aggression between individuals observed.

• Key Behaviors
• terricolous
• fossorial fossorial
• saltatorial saltatorial
• nocturnal nocturnal
• motile motile
• hibernation hibernation

Home Range

These toads typically stay close to bodies of water, but they have been observed up to 500 meters away from these water bodies.

Communication and Perception

• Communication Channels
• acoustic acoustic
• chemical chemical

• Perception Channels
• acoustic acoustic

Food Habits

Common midwife toads eat mostly eats insects and other arthropods. They emerge from their burrows at dusk and begin to feed on beetles, maggots, caterpillars, woodlice, spiders, slugs, snails, millipedes, worms, harvestmen, and others. After foraging, they return to their hiding space before dawn. Common midwife toads have sticky tongues used to capture prey and tiny horny teeth used for chewing. Tadpoles are herbivores and feed on aquatic plants and other plant debris.

• Primary Diet
• carnivore carnivore
  • insectivore insectivore
  • eats non-insect arthropods
  • vermivore

• Animal Foods
• insects
• terrestrial non-insect arthropods
• mollusks
• terrestrial worms

Predation

When common midwife toads are threatened, they excrete a potent smelling toxin from the warts on their back to defend against predators. This toxin is enormously effective and can be deadly; within hours the toxin can kill an adder (venomous snake). Tadpoles cannot yet produce this toxin and are vulnerable to predators during their development. Fish and aquatic insects feed on tadpoles.

• Anti-predator Adaptations
• cryptic cryptic

Ecosystem Roles

Common midwife toads are undoubtedly host to various internal and external parasites, but the most serious threat to date is chytrid fungus.

Economic Importance for Humans: Positive

Common midwife toads may benefit humans by consuming arthropod pests. This species has also been used to research Lamarckian inheritance or epigenetics.

• Positive Impacts
• research and education
• controls pest population

Economic Importance for Humans: Negative

This species is harmless to human interest and values, unless ingested.

• Negative Impacts
• injures humans
  • poisonous poisonous

Conservation Status

Although common midwife toads are considered "least concern" (IUCN) and are still common and widespread in some areas, they are experiencing population declines as well as some localized extinctions. They are listed on Annex IV of the EU Habitats Directive as well as on Appendix II of the Bern Convention. Common midwife toads are protected by national legislation throughout much of their range and are considered "near threatened" on the Spanish national Red List. Central Spain has begun employing captive breeding programs as well as reintroductions. Potential reasoning for population declines could be general habitat loss, especially habitat lost to farming and degradation of breeding sites. Many habitats are fragmented which can cause population decline and loss of gene flow. Chytridiomycosis infection, caused by a fungal parasite, is becoming more common, causing some populations to severely decline or even disappear. Iridovirus and "red-leg disease" has also been reported in declining populations in recent years. Introductions of predatory fish, such as salmonids , into breeding pools has also become a considerable threat, particularly to hatchlings and tadpoles.

Additional Links

AmphibiaWeb

Encyclopedia of Life

Contributors

Jacquelyn Albert (author), Michigan State University, James Harding (editor), Michigan State University, Tanya Dewey (editor), University of Michigan-Ann Arbor.

References

Bosch, J., R. Marquez. 1996. Discriminant functions for sex determination in two midwife toads (Alytes obstetricans and A. cisternasii). Herpetological Journal , 6: 105-109.

Bosch, J., T. Beebee, B. Schmidt, M. Tejedo, I. Martinez-Solano, A. Salvador, M. Garcia-Paris, E. Recuero Gil, J. Willem Arntzen, C. Diaz Paniagua, R. Marquez. 2009. "Alytes obstetricans (Common Midwife Toad)" (On-line). IUCN Red List. Accessed December 02, 2014 at http://www.iucnredlist.org/details/55268/0 .

Marquez, R., J. Bosch, X. Eekhout. 2010. Intensity of female preference for call source level in midwife toads Alytes cisternasii and A. obstetricans. Behavior , 147(9): 1185-1199.

Van der Meijden, A. 2010. "Alytes obstetricans" (On-line). AmphibiaWeb. Accessed December 02, 2014 at http://amphibiaweb.org/cgi/amphib_query?where-genus=Alytes&where-species=obstetricans .

2014. "Common midwife toad (Alytes obstetricans)" (On-line). Evolutionarily Distinct and Globally Endangered. Accessed December 02, 2014 at http://www.edgeofexistence.org/amphibians/species_info.php?id=1374 .

2012. "Midwife Toad Conservation" (On-line). World Association of Zoos and Aquariums. Accessed December 02, 2014 at http://www.waza.org/en/site/conservation/waza-conservation-projects/midwife-toad-conservation .

2012. "Midwife Toad" (On-line). LadyWildLife. Accessed December 02, 2014 at http://ladywildlife.com/viewmainpageinfo.php?pid=midwifetoad .

2014. "Midwife toad Facts" (On-line). Soft School. Accessed December 02, 2014 at http://www.softschools.com/facts/animals/midwife_toad_facts/1062/ .