Landfill Use by Andean Condors in Central Chile

We here describe Andean Condors' (Vultur gryphus) use of the biggest landfill in Chile as a food source. We monitored the landfill between 2005 and 2022. Until 2013, there was an increase in the number of condors present in the landfill. Then the number decreased until 2016, coincident with an abundant food supply on a large spatial scale, due to high mortality of cattle that were affected by extreme drought and plentiful rabbit carcasses due to outbreaks of myxomatosis. The same temporal and numerical trends were observed in both sexes and all ages. Compared to published population parameters, in the landfill the proportion of immatures was higher and that of adult males was lower; therefore, the landfill could function as a subsidy mainly for the lower strata of the dominance hierarchy of this species. There was a strong seasonality, with a low presence of condors in the warm season and maximum numbers in the cold season, likely coinciding with seasonal movements of livestock between summer and winter range lands in the high mountains, resulting in lower food abundance for condors during the cold season. This is the first characterization of the use of a landfill by a high number of Andean Condors, use that could have implications for the species' population in central Chile. Despite the apparent positive effect as a subsidy, waste disposals can have detrimental effects due to condors' consumption of potentially dangerous compounds. This study underscores the opportunistic nature of the Andean Condor, a species that can take advantage of rubbish dumps. Long-term Andean Condor monitoring at landfills may serve as an indicator food supply over a large spatial scale, which should be considered in conservation strategies.