l kleptoparasites of other birds. The snake and serpent eagles of the genera Circaetus, Terathopius, and Spilornis predominantly prey on the great diversity of snakes found in the tropics of Africa and Asia. The eagles of the genus Aquila are often the top birds of prey in open habitats, taking almost any medium-sized vertebrate they can catch. Where Aquila eagles are absent, other eagles, such as the buteonine black-chested buzzard-eagle of South America, may assume the position of top raptorial predator in open areas. Many other eagles, including the species-rich Spizaetus genus, live predominantly in woodlands and forest. These eagles often target various arboreal or ground-dwelling mammals and birds, which are often unsuspectingly ambushed in such dense, knotty environments. Hunting techniques differ among the species and genera, with some individual eagles having engaged in quite varied techniques based their environment and prey at any given time. Most eagles grab prey without landing and take flight with it so the prey can be carried to a perch and torn apart.
The bald eagle is noted for having flown with the heaviest load verified to be carried by any flying bird, since one eagle flew with a 6.8 kg (15 lb) mule deer fawn. However, a few eagles may target prey considerably heavier than themselves; such prey is too heavy to fly with, thus it is either eaten at the site of the kill or taken in pieces back to a perch or nest. Golden and crowned eagles have killed ungulates weighing up to 30 kg (66 lb) and a martial eagle even killed a 37 kg (82 lb) duiker, 7–8 times heavier than the preying eagle. Authors on birds David Allen Sibley, Pete Dunne, and Clay Sutton described the behavioral difference between hunting eagles and other birds of prey thus (in this case the bald and golden eagles as compared to other North American raptors):
They have at least one singular characteristic. It has been observed that most birds of prey look back over their shoulders before striking prey (or shortly thereafter); predation is after all a two-edged sword. All hawks seem to have this habit, from the smallest kestrel to the largest Ferruginous – but not the Eagles.
Among the eagles are some of the largest birds of prey: only the condors and some of the Old World vultures are markedly larger. It is regularly debated which should be considered the largest species of eagle. They could be measured variously in total length, body mass, or wingspan. Different lifestyle needs among various eagles result in variable measurements from species to species. For example, many forest-dwelling eagles, including the very large harpy and Philippine eagles, have relatively short wingspans, a feature necessary for being able to maneuver in quick, short bursts through dense forested habitats. Eagles in the genus Aquila, though found almost strictly in open country, are superlative soarers, and have relatively long wings for their size.
These lists of the top five eagles are based on weight, length, and wingspan, respectively. Unless otherwise noted by reference, the figures listed are the median reported for each measurement in the guide Raptors of the World in which only measurements that could be personally verified by the authors were listed.
|Rank||Common name||Scientific name||Body mass|
|1||Steller's sea eagle||Haliaeetus pelagicus||6.7 kilograms (15 lb)|
|2||Philippine eagle||Pithecophaga jefferyi||6.35 kg (14.0 lb)|
|3||Harpy eagle||Harpia harpyja||5.95 kg (13.1 lb)|
|4||White-tailed eagle||Haliaeetus albicilla||4.8 kg (11 lb)|
|5||Martial eagle||Polemaetus bellicosus||4.6 kg (10 lb)|
|Rank||Common name||Scientific name||Total length|
|1||Philippine eagle||Pithecophaga jefferyi||100 cm (3 ft 3 in)|
|2||Harpy eagle||Harpia harpyja||98.5 cm (3 ft 3 in)|
|3||Wedge-tailed eagle||Aquila audax||95.5 cm (3 ft 2 in)|
|4||Steller's sea eagle||Haliaeetus pelagicus||95 cm (3 ft 1 in)|
|5||Crowned eagle||Stephanoaetus coronatus||87.5 cm (2 ft 10 in)|
|Rank||Common name||Scientific name||Median wingspan|
|1||Philippine eagle||Pithecophaga jefferyi||220 cm (7