Dietary biology of the Eurasian eagle-owl
In the Iberian peninsula, the Eurasian eagle-owl is part of a complex guild of predators that have evolved to survive mostly on European rabbits. Among this guild, golden eagles ("Aquila chrysaetos") were recorded per one study to rely on rabbits for 40% of the diet, the eagle-owl for 49% of the diet, the Spanish imperial eagle ("Aquila adalberti") for 50% of the diet, the Bonelli's eagle ("Aquila fasciata") for 61% of the diet and the Iberian lynx ("Lynx pardinus") for 79% of the diet. Elsewhere, the Spanish imperial eagle and eagle-owl are considered to outflank the golden and even the Bonelli's eagle as the most specialized avian predator of rabbits in the Iberian region. Other predators, such as common buzzard ("Buteo buteo"), northern goshawk ("Accipiter gentilis") black kite ("Milvus migrans") Iberian wildcat ("Felis silvestris tartessia"), red fox, stone marten ("Martes foina") and introduced Egyptian mongoose also prey heavily on rabbits in Spain, but are more generalized and less reliant than the above predators. All these powerful predators do not generally compete directly for food but conflicts may ensue over the rights to territories and nesting sites amongst the birds. Being nocturnal in activity, however, the Eurasian eagle-owl does not tend to compete as directly as do the three eagle species and even these are discreetly segregated by habitat preferences, the goldens preferring open, steep cliffs, the Bonelli's favoring densely vegetated areas mixed with rocky spots and the imperial favoring relatively flat open woodlands. Among these eagles, the golden eagle tends to have the most similar habitat preferences to the Eurasian eagle-owl and across a broad band of overlapping distribution, the two are considered nearly ecological equivalents by day and night. However, good-sized female golden eagles are up to twice as heavy as an average eagle-owl, so seem to have a considerable advantage in size and power. Conversely, to support their large size and large territory needs, the golden eagle cannot survive on small and diverse prey nearly as successfully as the eagle-owl. Among the Iberian peninsula rabbit-eating guild, the species with wider ranges, the eagle-owl and the golden and Bonelli's eagles, have had some degree of success living off of alternate prey following the devastation of the rabbit population due to rabbit haemorrhagic disease. The two rabbit predators endemic to Iberia, the Iberian lynx and Spanish imperial eagle, have been devastated by the reduction and other causes and both are threatened species today.
Verreaux's eagle-owl
Among mammalian carnivores the bulk of predatory incidents have reportedly involved mongooses. Common, social species from savanna-edge such as the yellow mongoose ("Cynictis penicillata") and the meerkats ("Suricata suricatta") have been attacked, as well as larger, shy forest dwellers such as the Jackson's mongoose ("Bdeogale jacksoni"). An adult Meller's mongoose ("Rhynchogale melleri") weighing about which was taken by a Verreaux's eagle-owl on the wing represents the second heaviest known object successfully flown with this species after the aforementioned half-grown vervet monkey. Other smallish carnivores known to fall prey to Verreaux's eagle-owls include the African striped weasel ("Poecilogale albinucha") and its larger cousin, the striped polecat ("Ictonyx striatus"), which in one nest from the border of the Kalahari represented the sole prey species for a pair of eagle-owls. In southern Africa, both the cape genet ("Genetta tigrina"), averaging , and the black-footed cat ("Felis nigripes"), the smallest felid in Africa, have been included amongst their prey. The Verreaux's eagle-owl is thought to be a threat to even larger carnivores, including the bat-eared fox ("Otocyon megalotis") and the aardwolf ("Proteles cristata"), although whether healthy adults of the latter are in danger is doubtful. An scientifically-observed attack on an adult African wildcat ("Felis silvestris cafra"), which averages about , was aborted after the eagle-owl apparently deemed that the felid was too heavy to take flight with. However, domesticated cats of any size may fall prey to Verreaux's eagle-owl. At Lake Baringo Country Club in Kenya, this eagle-owl has apparently taken to habitually hunting outdoor cats, reportedly making the cats on the grounds highly skittish.