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Regions > Conservation Efforts > Puerto Rican Crested toad
Puerto Rican Crested toad
Location at the Zoo: Conservation Efforts
Scientific Name: Bufo lemur
Puerto Rican crested toads have prominent bony ridges above the eyes (which are more pronounced in females), enclosing a deep hollow between the eyes. They have a distinctive, long, upturned snout and the upper lip is expanded horizontally forming a projecting bony rim around the mouth. They are densely covered with warts and numerous blackish spines. They are a medium-sized toad, measuring 64 - 120 mm from snout to vent, with females being larger than males. They range in colour from brown to yellow brown and have black or brown patches, which are more distinctive in females. The back and the ventral surface is a cream colour. Adult males are more yellowish in colour (especially during breeding season) and have a smoother skin.
Puerto Rico (Guanica Forest) on the south coast; considered by the Puerto Rican Department of Natural and Environmental Resources to be extirpated in the northern part of their range. This is the only native species of toad found in Puerto Rico. Captive bred toads have been introduced to the south in Coamo, and near Arecibo in the north.
In the south, dry sub-tropical forest with low elevation, arid or semi-arid rocky areas with an abundance of limestone fissures (karst) and cavities in well-drained soil. Northern Puerto Rico toads are found in limestone (karst) forests.
Unknown, although thought to be nocturnal invertebrates and those which share stone and cavity toad refuges; most likely beetles, snails, or sow bugs observed under limestone during field research.
Reproduction and Development:
Puerto Rican crested toads breed in seasonal pools formed during the rainy season. There may be over two years between breeding events, depending on the frequency of storms. An accumulation of more than 10 cm of water in 24 hours is followed by the emergence of males into the breeding areas. This is followed by the females gathering at the pond, in which they breed. They mate, deposit their egg strands on submerged vegetation, and leave the pond, usually within 24 hours. The toads breed in one pond on the southwestern coast and formerly in no more than four man-made cattle troughs in the northwest. They show a high fidelity to breeding sites. Eggs hatch in approximately 24 hours. There is an 18 day (range 15 - 25) larval period before metamorphosis.
Very fast development so that toadlets can leave the ponds before they dry up. Newly metamorphosed toads seek refuge as soon as they leave the water. This has an adaptive advantage in the wild, as ground temperatures exceed 45 degrees Celsius around the drying breeding ponds in Puerto Rico. A single mass of toadlets in one clump reduces the ratio of surface area to body mass with a corresponding reduction in evaporative water loss. Typically, 15 - 30 toadlets will clump in one mass under any available object and will conform to the shape of the space under the shelter. The bony head has been observed closing off the entrance to holes that toads back into, and may assist in protecting the toads from moisture loss or predation.
Threats to Survival:
The most immediate threat is loss of habitat. There is only one remaining natural breeding pond left in the Guanica Forest. There are an estimate of only 3000 toads in the southern population, and no more than 25 in the northern population. The Puerto Rican DNR considers the northern population to be extirpated because none have been seen since 1989, despite suitable breeding conditions. In the south, the toads breed in the Tamarindo section of the Guanica Forest. The breeding pond is located within 100 m of the sea, and could be breached or inundated by heavy seas during severe storms or hurricanes. The site serves as a parking lot for users of a nearby beach during the dry season. Proposed hotel development may result in further loss of habitat and/or water supply.
Introduced fauna also poses a threat to the survival of the Puerto Rican crested toad. The much larger and far more numerous marine toad (Bufo marinus) that was introduced from Jamaica to control sugar pests may compete with and displace the Puerto Rican toad. The introduced Indian mongoose (Herpestes auropunctatus) preys on the toad. Agro chemical contamination of temporary ponds may also occur due to the use of pesticides in land surrounding breeding ponds. Cooperating agencies have constructed ponds in suitable habitat (outside migratory range of existing natural breeding ponds). Constructed ponds are used for release of captive bred tadpoles.
IUCN: Critically Endangered