Risks to Colombian Amphibian Fauna from Cultivation of Coca (Erythroxylum coca): A Geographical Analysis

Abstract

The Colombian amphibian fauna is among the richest known in the world, with about 20 species of salamanders (order Caudata), 35 of the limbless caecilians (order Gymnophiona), and more than 700 species of frogs and toads (order Anura) recorded from localities within the country. The potential effects of exposure to glyphosate on amphibians arising from production of illegal crops (coca) were examined. The analysis was based on (1) behavior and ecology of species and (2) proximities of actual museum records to localities in which illegal crops are being grown and the subset of those that have been sprayed with glyphosate. Based on data on the location of amphibians collected in Colombia, records were obtained for 193 species (28% of the national diversity) of frogs and toads found in localities within 10 km of areas where coca is grown. Further analyses with ARC MAP software allowed for measurement of the direct distance separating collection locations for frogs, known coca fields, and areas where aerial spraying was being conducted. Records in or near coca fields included data for 11 of 13 families of frogs and toads known to be present in Colombia. Only Ceratophryidae and Pipidae were not reported from these locations and appear not to be at risk. For eight species (Dendrobates truncatus, Craugastor raniformis, Pristimantis gaigeae, Smilisca phaeota, Elachistocleis ovale, Hypsiboas crepitans, Trachycephalus venulosus, and Pseudis paradoxa) selected to represent several habitat preferences and life-cycle strategies, large areas of their distributions lie outside coca production regions and their populations as a whole are at low risk. For a limited number of species that barely enter Colombian territory, the consequences of coca production may be more serious and may have placed several species of frogs at risk. These include Ameerega bilingua, Dendropsophus bifurcus, Pristimantis colomai, P. degener, P. diadematus, P. quaquaversus, P. variabilis, and Trachycephalus jordani. Other species may also be at risk but exact numbers are unknown since few investigations were undertaken in these areas during the past 30 yr. The main ranges for these species were assumed to be in Ecuador.

The authors gratefully acknowledge the contributions of Policia Antinarcótica de Colombia, which provided mapping data on the location of coca production and aerial eradication spraying.

Notes

∗The classification of amphibians is subject to much debate and instability at this time and the authors acknowledge that nomenclature will change in the near future. The nomenclature used in this paper is current at this time except that Hedges et al. (2008a) is not followed in their partition of the family Brachycephalidae into four families because that study was a phenetic one masquerading as a phylogenetic study (furthermore, all new names proposed therein are not available because the paper did not meet Article 13.1.1; ICZN, 1999), and Wiens et al. (2005, 2007) rather than Frost et al. (2006) as concerns the Hemiphractidae were followed.