Diet and Foraging

Great Black Hawks are dietary generalists (Ferguson-Lees and Christie 2001, Gerhardt et al. 2012, Clark and Schmitt 2017). A nest study in southeastern Brazil in which two nests were followed (one across five breeding seasons and one during a single breeding season) identified 31 prey items brought to the nest: 10 amphibians (32.3%); 10 mammals (32.3%); 6 reptiles (all snakes; 19.4%); 4 birds (12.9%); and 1 insect (3.2%) (Carvalho Filho et al. 2006). Seavy and Gerhardt (1997) documented a similar variety in diet for Great Black Hawks at Tikal, Guatemala, where they identified 126 prey items at least to class. Prey delivered to nestlings included 41 lizards (32.5%); 34 snakes (27.0%); 24 mammals (19.1%); 16 birds (12.7%); 8 anurans (6.4%) and 3 insects (2.4%). More than 70% of the lizards in the Guatemalan study referred to basilisk lizards (Basiliscus vittatus). Great Black Hawk has been observed to feed on carrion, such as a dead cayman in a rice field (Haverschmidt 1962), dead snakes killed by traffic (Haverschmidt 1968), and washed-up shellfish and crabs on the beach in Colombia (Todd and Carriker 1922). In southwestern Brazil, it has been observed to chase Plumbeous Ibis Theristicus caerulescens off the nest to eat the eggs (Olmos 1990), while in Costa Rica, an adult Great Black Hawk was observed predating a nest of Bare-throated Tiger-Heron Tigrisoma mexicanum by eating a nestling as the adult tiger-heron stood nearby (Lewis and Timm 1991). Nest attacks also are described at colonies of Yellow-rumped Caciques Cacicus cela (Robinson 1985) and of Russet-backed Oropendolas Psarocolius angustifrons (Robinson 1994) in Manu National Park, Madre de Dios, Peru. Groom (1992) describes Great Black Hawk as the second-most frequent avian predator, after Black Caracara Daptrius ater, of mixed species beach-nesting colonies consisting of Sand-colored Nighthawks Chordeiles rupestris, Black Skimmer Rynchops niger, Large-billed Tern Phaetusa simplex, and Yellow-billed Tern Sternula superciliaris. Stomach contents of two specimens from Brazil included a lizard, a snake, frogs, and a bird the size of a thrush (Schubart et al. 1965). Insects also are included in the diet, including Hemiptera Heteroptera (Belostomatidae) and Orthoptera (Locustidae, Acrididae) (Haverschmidt 1968).

Great Black Hawk utilizes a diverse array of foraging techniques includes still-hunting, especially from low perch at waterside, and wading in shallow water, to short flights from perch to perch, and transect-flights over open areas (Stiles and Skutch 1989, Clark and Schmitt 2017).