Mallorcan midwife toad (Alytes muletensis)
|Also known as:||Ferreret|
|Size||Male length: up to 34.7 mm (2)|
Female length: up to 38 mm (2)
Classified as Vulnerable (VU D2) on the IUCN Red List 2004 (1).
This unusual toad gains its name from the fact that males care for the developing eggs (2). Adults have a large head and long legs in relation to the body, the eyes are large and golden with a narrow vertical pupil (2). The skin is usually golden-brown in colour with a number of darker brown, green or black blotches, whilst the underparts are off-white (6). There is often a black triangle between the eyes. Males and females are difficult to distinguish from their appearance (2).
Endemic to Mallorca, an island off the east coast of Spain (2), this toad is currently found in gorges (4) in the Sierra de Tramuntana Mountains (2). The distribution was once considerably larger than at present; recent surveys estimate there may now be as few as 500 breeding pairs remaining (4).
This toad inhabits inaccessible brooks in limestone gorges and hides under stones and in crevices (2).
The Mallorcan midwife toad has an unusual breeding system. Intense competition for males occurs amongst females, who grapple with each other over mates (3). In common with other members of this unusual genus, males carry the developing eggs until the tadpoles hatch (3). Males carrying eggs are seen in May and June, with between 7 and 12 eggs wrapped around their ankles in strings (3). The first tadpoles hatch in May, measuring around 18 mm in length. Tadpoles metamorphose any time from late June to September and some may even over-winter as tadpoles and metamorphose the following summer (6). Males produce a high-pitched 'pi...pi...pi' call, which attracts females and may help to stimulate the maturation of eggs by the female (2); females also vocalise to advertise when they are receptive (3). Adults are generally active at night and they do not hibernate (3).
This species was identified from fossils in the 1970s and was believed to have become extinct 2000 years ago, incredibly however, surviving populations were discovered in 1980 (3). Since then this toad has decreased markedly in abundance and range. The decline in the Mallorcan midwife toad was the result of the introduction to the island of competitors and predators such as the viperine snake (Natrix maura), which predates on both adult toads and tadpoles, and the green frog (Rana perezi) (4) that competes for food (2). Increased demands for water due to the large number of tourists visiting the island places pressure on mountain water resources, and a number of schemes have proposed to dam the rivers in which this toad lives. A further threat arises from the small size of the remaining population, which places the species at risk of extinction from chance catastrophic events (2).
A conservation project is underway, with cooperation between the Mallorcan Consellaria de Medi Ambient, Durrell Wildlife Conservation Trust, the Durrell Institute of Conservation and Ecology at Kent University and the Barcelona Zoo (5) (6). The species breeds well in captivity and reintroductions have been taking place since 1988, with several breeding populations already successfully established as a result (4). Annual surveys are taking place and a reserve has been proposed to help protect the species (4). The number of suitable sites for reintroduction is limited, so work is currently focusing on the creation of new pools (4). With such concerted conservation efforts, the future of this fascinating species may well be secured, at least for the present.
For more information on the Mallorcan midwife toad see:
Durrell Wildlife Conservation Trust
The Declining Amphibian Populations Task Force
EDGE of Existence:
Information authenticated (12/6/03) by Richard Gibson, Curator of Herpetology, Zoological Society of London.
- Endemic: a species or taxonomic group that is only found in one particular country or geographic area.
- Genus: a category used in taxonomy, which is below ‘family’ and above ‘species’. A genus tends to contain species that have characteristics in common. The genus forms the first part of a ‘binomial’ Latin species name; the second part is the specific name.
- Hibernate/ Hibernation: a winter survival strategy characteristic of some mammals in which an animal’s metabolic rate slows down and a state of deep sleep is attained. Whilst hibernating, animals survive on stored reserves of fat that they have accumulated in summer. In insects, the correct term for hibernation is ‘diapause’, a temporary pause in development and growth. Any stage of the lifecycle (eggs, larvae, pupae or adults) may enter diapause, which is typically associated with winter.
- Metamorphosis: an abrupt physical change from the larval to the adult form.
IUCN Red List (November 2004)
Amphibia Web (February, 2002)
- Gibson, R. (June, 2003) Pers. comm.
Froglog IUCN/SSC Declining Amphibian Populations Task Force. August 1994 No. 10
Open University (February, 2002)
Durrell Wildlife Conservation Trust (Previously the Jersey Wildlife Preservation Trust) (September, 2002)