Impacts of the 1982-1983 El Nino on Population Dynamics of Andean Condors in Peru

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Abstract
We studied how the environmental perturbations associated with the 1982-1983 El Nino phenomenon affected the population dynamics of Andean condors (Vultur gryphus) in three areas of Peru. For at least four years prior to the 1982-1983 El Nino, nearly all adult condors in a coastal population and an Andean foothill population refrained from breeding; whereas condors in a high-elevation population appeared to be breeding once every other year. The severe environmental disruptions of the 1982-1983 El Nino caused the food supply for the coastal population of condors to decrease, while the food supply for the foothill population increased 17 fold. The food supply for the high-elevation population was little affected by El Nino because climatic changes in the area were inconsequential. In response to the increase in food, almost all condors in the foothill population bred in the months following El Nino. No condors in the coastal population bred after El Nino, and breeding of condors in the high-elevation population was presumably unaffected. If they can reproduce only during the unpredictable El Nino years, coastal and foothill condor populations may barely be able to maintain their numbers without ingress from more regularly breeding populations. The rate of breeding in these desert-dwelling condors seems to be the lowest recorded among birds.