Dietary biology of the golden eagle
Owls, which may have dissimilar periods of activity, are not entirely exempt from golden eagle predation either. Several species have been recorded as prey, especially in Northern Europe, Slovakia (where owls make up 2.4% of prey remains) and some parts of the Western United States. Species hunted have ranged in size from tiny Eurasian pygmy owl ("Glaucidium passerinum") and little owl ("Athene noctua") to the formidable, large great horned, Eurasian eagle and great gray owls ("Strix nebulosa"). Barn owls ("Tyto alba") have been predated by golden eagles in both North America and Eurasia. On Santa Rosa and Santa Cruz Islands, barn owls made up 4.5% of the diet, the largest known occurrence of that species in the eagles' diet. However, the great horned owl is the owl species that occurs most regularly in the diet of North American golden eagles. In Europe, golden eagles are relatively minor predators of owls compared to Eurasian eagle-owls and northern goshawks. The primary owls hunted by European eagles are Ural owls ("Strix uralensis") and short-eared owls ("Asio flammeus"). Few eye-witness accounts are known of owl predation, but one violent mid-day confrontation between a golden eagle and an adult great horned owl was witnessed in Jefferson County, Colorado. Although this owl was about a third of the eagle's weight, it was able to land some damaging blows on the larger bird. In the end, despite its wounds, the eagle was victorious over the dead owl. A case of kleptoparasitism by a golden eagle on a great horned owl has been recorded. Although the Eurasian eagle-owl is preyed upon by golden eagles (4 confirmed cases of golden eagles killing eagle-owls in Europe), in one case a golden eagle (age unspecified) was found amongst the prey in an eagle-owl nest.
Spot-bellied eagle-owl
This is a very powerful and bold predatory owl, which is assuredly at the top of the avian food chain in its forested range. However, no extensive study of its dietary habits is known. Even in larger eagle-owls such as the Eurasian eagle-owl, although they can and do prey on a wide range of prey including impressively large prey, most of the diet consists of small mammals, often small rodents such as voles and rats. There is no reason to assume that the spot-bellied eagle-owl does not also take a very large quantity of relatively small prey such as rodents until complete dietary studies are known. However, almost all of the prey thus far reported for this species is very large and impressive, much of it being presumably as heavy or heavier than the eagle-owls themselves. Due to being most widely reported as being chased and eaten by spot-bellied eagle-owls has led some authors to list their primary prey as pheasants. Among these, junglefowl ("Gallus" sp.) and kalij pheasants ("Lophura leucomelanos"), both weighing from , are commonly eaten, as well as Indian peafowl ("Pavo cristatus"), which can weigh anything from . The spot-bellied eagle-owl pounces on gamebirds while they're asleep on their perches in trees or bamboo clumps, often killing them in seconds with their powerful talons. Cases, where they've followed peafowl to their roosts and then pulled them out at sundown, have been reported. It also consumes an array of mammals, from small rodents to large prey such as apparent adults of golden jackals ("Canis aureus"), hares ("Lepus" ssp.), large Indian civets ("Viverra zibetha"), Indian spotted chevrotains ("Moschiola indica"), and even young muntjacs ("Muntiacus" sp.). These larger mammals are likely as much as or even more. While most reported prey appear to be largely terrestrial, they are known to capture arboreal prey including Indian giant squirrel ("Ratufa indica") and juvenile purple-faced langur ("Trachypithecus vetulus"). Additionally, they are considered a potential threat to toque monkeys ("Macaca sinica"), and one apparently caught an Indian flying fox ("Pteropus giganteus") from its tree roost. Due to the capture of diurnal prey such as giant squirrel, partial daytime foraging habits have been inferred for the spot-bellied eagle owl. They will also opportunistically prey upon snakes, lizards (including large monitor lizards) and fish. Like several of the eagle-owls and fish owls but unlike most owls, the spot-bellied eagle-owl has been recorded as feeding on carrion. Thus far, they've been seen feeding on the carcases of goats ("Capra aegagrus hircus") and tigers ("Panthera tigris").