Evaluating the importance of native prey species to the diet of Andean condors in the high Andes of northwestern Argentina
P. L. Perrig
The Andean Condor (Vultur gryphus), the largest flying bird in the New World and an emblematic animal of South America, is declining in abundance range-wide and critically endangered at the northern half of its distribution. Different human activities affect the species, but the most widespread and insidious threat faced by Andean condors involves decreasing availability and abundance of important native food resources. To date, Andean Condor diets and foraging ecology have not been studied in areas with abundant native prey; thus, the relative importance of native and non-native food items to Andean Condors across their range remains unclear. Furthermore, the mechanisms that provide condors with food have not been previously studied. The objectives of this project were to (1) evaluate the importance of native wild camelids (vicuñas Vicugna vicugna and guanacos Lama guanicoe) as food sources to condors in an undisturbed protected area of the Andes, comparing our findings with results from condor habitats dominated by livestock and non-native game species; and (2) evaluate mortality causes of carcasses used by condors to understand the mechanisms that make carrion available to these scavengers.
Andean condor diets were analyzed under varying abundances of native and exotic prey in three protected areas in Central Argentina. Pellet content analysis indicated a positive relationship between prey consumption and its density across sites. Native camelids dominated the diet of Andean condors at two protected areas and represented half of the biomass consumed in a third reserve. While in northwestern Patagonia condors depend heavily on exotic prey, some protected areas in central Argentina are still conserving a safe food resource for Andean Condors. During January-July, 2013 field necropsies were conducted and 45 fresh camelid carcasses were monitored at San Guillermo National Park, considered one of the most functionally intact ecosystems in the region. Eighty-nine percent of the carcasses found showed signs of puma predation and 98% were scavenged, of which 45% were foraged by condors. These results suggest that functional linkages between condors, pumas and camelids are strong where trophic interactions are preserved, and can serve as a baseline for setting conservation goals in other areas of South America. The identification and protection of areas with adequate and safe food resources is paramount for the conservation of condor populations. Our results indicate that the most stable and productive condor populations might persist where pumas and camelids exist in abundance, and protected areas are key for the successful conservation and recovery of these species. ($7,460)