Puerto Rican Crested Toad
Puerto Rican Crested Toad
|Listed||August 4, 1987|
|Description||Medium-sized toad; yellow-olive to dark brown in color; distinctive long, upturned snout.|
|Habitat||Coastal plain on exposed limestone or porous soil.|
|Reproduction||Egg masses laid in freshwater ponds.|
|Threats||Loss of habitat.|
The Puerto Rican crested toad is a medium-sized toad, 2.5-4.5 in (6.3-11.4 cm) in snout-vent length, yellowish-olive to blackish-brown in color, with prominent supraorbital crests and a distinctive long, upturned snout. Males are considerably smaller than females, and exhibit less prominent crests. No studies have been conducted on the Puerto Rican crested toad's feeding habits, but as a general rule toads are opportunistic feeders that primarily consume insects and other invertebrates.
Although not completely understood, breeding appears to be sporadic and highly dependent upon occasional heavy rains. When rainfall and surface water are adequate, more than one breeding event may occur in a single season. Breeding is concentrated in a very short period, and within a few weeks the toadlets metamorphose and quickly disperse. There is a high fidelity in breeding sites that offer the right combination of elevation, topography, and ponded fresh water.
The Puerto Rican crested toad occurs at low elevations (below 660 ft or 200 m) where there is exposed limestone or porous, well-drained soil offering an abundance of fissures and cavities. Adult toads are semifossorial and widely dispersed when not breeding. Because of this cryptic behavior, the location or even presence of adult toads when not breeding is difficult to detect.
This toad is presently known to exist only on the main island of Puerto Rico. A single large population is known from the southwest coast in the Guánica Commonwealth Forest, and a small population is believed to survive on the north coast. It has also been collected on the southern coastal plain near Coamo. Northern coastal plain collections have been made near Isabela, Quebradillas, Arecibo, Barceloneta, Vega Baja, and Bayamón. The species has also been propagated in captivity and approximately 850 toadlets were released in Cambalache Commonwealth Forest on the north coast in 1984 and 1985. To date, more than 4,000 toadlets have been produced in captivity at the Metro Toronto Zoo and returned to Puerto Rico.
Historically, the Puerto Rican crested toad has been collected on the island of Virgin Gorda in the British Virgin Islands. The known historic distribution on Virgin Gorda is very limited and the species has not been observed there for at least two decades. It is assumed to have been extirpated from that island. Exact numbers are unknown. The Guánica Commonwealth Forest population is relatively stable and consists of approximately 1,500-2,000 individuals. The northern population consists of approximately 25 individuals. Nothing is known about population numbers in other localities, especially since the species is very difficult to encounter on a periodic basis.
Loss of habitat from filling and drainage of breeding sites, and direct loss of adults and their habitat during land development are considered the primary factors for the toad's present status. Although the Puerto Rican crested toad has historically been rare, the species has undoubtedly declined further as its coastal lowland habitat has been destroyed by agricultural and urban development. In particular, known breeding sites have been filled or drained for construction, cultivation, and mosquito control. Construction projects are currently proposed which could affect the toad's status in the Guánica Commonwealth Forest area; however, discussions are continuing in an effort to find alternatives that will avoid destruction of toad breeding habitat.
Secondary factors may also be affecting the species' status. Predation on dispersing toadlets may be heavy, particularly from wading birds, and could become a significant factor if populations are greatly reduced by other problems. Additionally, reproduction in this species appears to rely on climatic events, sometimes one or more years apart, that occur at irregular intervals. Such reliance may create natural fluctuations in population sizes that could, when compounded by a reduced availability of breeding sites, increase the likelihood of whole subpopulations being eliminated. Extremes in sex ratios have also been reported; a low incidence of males in one area, and a low incidence of females at another locality However, the significance of these observations is difficult to assess without more information about the reproductive biology of this species.
Conservation and Recovery
Protection of habitat is considered the highest priority need. Limited numbers of breeding sites are apparently used by toads from a large surrounding area. In one case, a marked and recaptured female traveled 2.4 mi (3.8 km). The conservation of whole subpopulations may be dependent on the identification and protection of these sites. Additional surveys are needed to better determine the species' distributions and abundance. Should reintroduction be necessary, captive breeding has been successfully accomplished in the past and could be used again to provide individuals for this purpose.
U.S. Fish and Wildlife Service
Regional Office, Division of Endangered Species
1875 Century Blvd., Suite 200
Atlanta, Georgia 30345
Boquerón Ecological Services Field Office
U. S. Fish and Wildlife Service
P.O. Box 491
Boquerón, Puerto Rico 00622-0491
Telephone: (787) 851-7297
Fax: (787) 851-7440
Garcia Diaz, J. 1987. "Rediscovery of Bufo lemur Cope and Additional Records of Reptiles from Puerto Rico." Stahlia 10: 1-6.
Paine, F.L. 1985. "International Studbook of the Puerto Rican Crested Toad (Peltophryne lemur )." Buffalo Zoological Gardens, New York. 33 pp.
Pregill, G. 1981. "Cranial Morphology and the Evolution of West Indian toads (Salientia: Bufonidae): Resurrection of the Genus Peltophryne Fitzinger." Copeia 1981: 273-285.
Rivero, J.A., H. Mayorga, E. Estremera, and I.Izquierdo. 1980. "Sobre el Bufo lemur Cope (Amphibia, Bufonidae)." Caribbean Journal of Science 15: 33-40.
U.S. Fish and Wildlife Service. 4 August 1987. "Determination of Threatened Status for the Puerto Rican Crested Toad." Federal Register 52 (149): 28828-28831.