Diet of the Southern Caracara in a near-shore insular system in southern Patagonia, Argentina

Abstract

The Southern Caracara (Caracara plancus) diet is little known in continental areas, but nothing is known about its diet in insular areas. We reported the food habits of Southern Caracaras in four near-shore islands located in Chubut province, southern Argentina. Between March 2013 and February 2017 we collected pellets (N = 306) on three islands (Leones, Tova and Galfrascoli) and disaggregated food remains (N = 146) on one island (Tovita). We measured the importance level of each food item by calculating the percentage of total food item (%TP) and percentage of occurrences (%OC). Southern caracaras consumed a variety of animal food including vertebrates and invertebrates. The most frequent food items in the pellets were the Magellanic penguin (Spheniscus magellanicus) and insects, whose importance level showed some variation among islands (penguins: %TP = 26.1–38.5%, OC = 83.7–95.3; insects: TP = 1.3–25.9, OC = 2.9–76.1). In the pellets collected in Tova island, we also found a great proportion of South American sea lion (Otaria flavescens; %TP = 22.9, %OC = 50.7). In the food remains, the most frequent animal food items were the Magellanic penguin (%TP = 28.8) and European rabbit (Oryctolagus cuniculus) (%TP = 44.7). Apparently, the large-sized animals (penguins, sea lions and adult rabbits) were taken as carrion. Because all these animal species are common on islands, we think that caracaras taken them opportunistically. In agreement with previous studies, our results show that the Southern Caracara on islands is also an opportunistic, scavenger and insect-eating species.