A long-term study into the usage of Chile's largest landfill site by Andean Condors has produced some fascinating data.
The 17-year-long research period revealed that Loma Los Colorados, north of the capital city of Santiago, hosts the largest known gatherings of Andean Condors at a single site anywhere in the world.
The paper, published in the Journal of Raptor Research, also explains how condor numbers at the landfill are directly linked to the presence of available food in the surrounding landscape, namely the carcasses of cattle and rabbit.
The researchers also found that condor numbers at the site fluctuate depending on the movements of grazing livestock across the region, and that the age and sex ratios of condors at the landfill suggest those at the bottom of the social ladder (juveniles and females) visit the landfill more often than adult males.
Andean Condors gather in large numbers at Chile's largest landfill site, Loma Los Colorados (Colin Drake).
Surviving on landfill
In central Chile, human livestock practices strongly influence the distribution of carrion available to Andean Condors. Landfills are predictable, and predictable food sources often alter the movement patterns of wildlife species. Understandably, most animals will avoid working hard to find food if they can.
Although the presence of landfills can aid in condor survival by offering a reliable food source, they can also harm condors at the individual and population levels. Over the course of the study, the team observed four poisoning events affecting 14 condors, eight of which died as a result. Most of the afflicted were males, likely because adult males are dominant over other condors at desirable food items. When those choice items are toxic, the males experience the worst of it. These poisonings were due to organophosphorus intoxication; however, the exact sources were never revealed.
Notably, condor numbers at the landfill decreased between 2013 and 2016, correlating with widespread cattle mortality due to drought, and rabbit mortality due to myxomatosis disease, both of which increased the availability of food sources (carcasses) in the regional landscape. Both mortality events subsided after 2019 and condor numbers at the landfill increased again.
The authors recommend that landfill management companies work to reduce the presence of garbage available to the condors, and implement feeding stations during times of food hardship, primarily during the austral winter.
Reference
Pavez, E F, Pascual, P, & González, B A. 2023. Landfill Use by Andean Condors in Central Chile. Journal of Raptor Research. DOI: https://doi.org/10.3356/JRR-22-00051
