BIOTROPICA 37(2): 190–201 2005 10.1111/j.1744-7429.2005.00026.x SPECIAL SECTION Catastrophic Population Declines and Extinctions in Neotropical Harlequin Frogs (Bufonidae: Atelopus) 1 Enrique La Marca 2 , Karen R. Lips 3 , Stefan L ¨ otters 4 , Robert Puschendorf 5 , Roberto Ib´ a˜ nez 6 , Jos ´ e Vicente Rueda-Almonacid 7 , Rainer Schulte 8 , Christian Marty 9 , Fernando Castro 10 , Jes ´ us Manzanilla-Puppo 11 , Juan El´ ıas Garc´ ıa-P ´ erez 12 , Federico Bola ˜ nos 13 , Gerardo Chaves 13 , J. Alan Pounds 14 , Eduardo Toral 15 , and Bruce E. Young 16 2 Laboratorio de Biogeograf´ ıa, Escuela de Geograf´ ıa, Facultad de Ciencias Forestales y Ambientales, Universidad de Los Andes, M´ erida, Venezuela, Apartado Postal 116, M´ erida 5101-A, Venezuela 3 Department of Zoology, Southern Illinois University, Carbondale, Illinois 62901-6501, U.S.A. 4 Ecology Department, University of Mainz, Institute of Zoology, Saarstrasse 21, 55099 Mainz, Germany 5 Escuela de Biolog´ ıa, Universidad de Costa Rica, San Pedro, Costa Rica 6 Smithsonian Tropical Research Institute, Apartado 2072, Balboa, Anc´ on, Republica de Panam´ a, and Universidad de Panam´ a, Departamento de Zoolog´ ıa, Panam´ a, Republica de Panam´ a 7 Programa Especies Amenazadas, Conservaci ´ on Internacional, Carrera 13, No.71-41, Bogot ´ a, Colombia 8 Instituto de Investigaci´ on Biol ´ ogica de las Cordilleras Orientales (INIBICO) Jr. Ram´ ırez Hurtado 608, Tarapoto, Per´ u 9 Impasse Jean Galot, 097354 Montjoly, Guyane Franc ¸aise, France 10 Laboratorio de Herpetolog´ ıa, Secci ´ on de Zoolog´ ıa, Facultad de Ciencias, Departamento de Biolog´ ıa, Universidad del Valle, Cali, Colombia 11 Museo del Instituto de Zoolog´ ıa Agr´ ıcola, Universidad Central de Venezuela, Maracay, Venezuela and Museo Nacional de Ciencias Naturales, Madrid, Espa ˜ na 12 Museo de Zoolog´ ıa, Programa de Recursos Naturales Renovables, Vice-Rectorado de Producci´ on Agr´ ıcola, UNELLEZ, Guanare, Estado Portuguesa, Venezuela 13 Escuela de Biolog´ ıa, Universidad de Costa Rica, San Pedro, Costa Rica 12 Golden Toad Laboratory for Conservation, Monteverde Cloud Forest Preserve and Tropical Science Center, Santa Elena, Puntarenas 5655-73, Costa Rica 15 Tarqui 19-26 y E. Espejo, Cuenca, Ecuador 16 NatureServe, Apartado 75, Monteverde, Puntarenas, 5655 Costa Rica ABSTRACT We surveyed the population status of the Neotropical toad genus Atelopus, and document recent catastrophic declines that are more severe than previously reported for any amphibian genus. Of 113 species that have been described or are candidates for description, data indicate that in 42 species, population sizes have been reduced by at least half and only ten species have stable populations. The status of the remaining taxa is unknown. At least 30 species have been missing from all known localities for at least 8 yr and are feared extinct. Most of these species were last seen between 1984 and 1996. All species restricted to elevations of above 1000 m have declined and 75 percent have disappeared, while 58 percent of lowland species have declined and 38 percent have disappeared. Habitat loss was not related to declines once we controlled for the effects of elevation. In fact, 22 species that occur in protected areas have disappeared. The fungal disease Batrachochytrium dendrobatidis has been documented from nine species that have declined, and may explain declines in higher elevation species that occur in undisturbed habitats. Climate change may also play a role, but other potential factors such as environmental contamination, trade, and introduced species are unlikely to have affected more than a handful of species. Widespread declines and extinctions in Atelopus may reflect population changes in other Neotropical amphibians that are more difficult to survey, and the loss of this trophic group may have cascading effects on other species in tropical ecosystems. RESUMEN Examinamos el estado poblacional de las ranas neotropicales del g´ enero Atelopus y documentamos disminuciones catastr´ oficas recientes, las m´ as dr´ asticas se˜ naladas para cualquier g´ enero de anfibios. De las 113 especies que han sido descritas o son candidatas para ser descritas, los datos poblacionales indican que en 42 especies, las poblaciones han sido reducidas por lo menos a la mitad y solamente diez especies tienen poblaciones estables. El estado de los taxa restantes es desconocido. Por lo menos 30 especies no han sido vistas en al menos ocho a ˜ nos de todas las localidades conocidas, y se teme que se hayan extinguido La mayor´ ıa de estas especies desaparecieron entre 1984 y 1996. Todas las especies con 1 Received 13 December 2004; revision accepted 20 December 2004. 190