Can a Eurasian eagle-owl kill a rabbit?
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.
Northern goshawk
Outside of the accipitrid group, heavy predation on different varieties of raptorial birds by northern goshawks can continue unabated. Many types of owl are taken and in Europe, the northern goshawk is the second most prolific predator of owls behind the Eurasian eagle owl ("Bubo bubo"). In Bavaria, Germany, the long-eared owl ("Asio otus") was the second most common prey species for nesting goshawks. In the Białowieża Forest of Poland, fairly high numbers of the tawny owl ("Strix alucco") were taken. In all, some 18 species of owl have been recorded in the diet, ranging in size from the Eurasian ("Glaucidium passerinum") and northern pygmy owls ("Glaucidium gnoma") at and , respectively, to all the large northern "Strix" owls including adults and even the great horned owl. Whether adults have ever been killed as prey though is unknown but goshawks have been known to kill great horned owls that they've found near their nests. In addition, about eight species of falcon have been identified in the foods of goshawks. Adult falcons of small species such as kestrels and merlins ("Falco columbarius") can be overpowered quite easily if they can manage to surprise the prey. Larger falcons have turned up in the diet as well, including the prairie falcon ("Falco mexicanus") and the saker falcon ("Falco cherrug"), although possible only nestlings of these species. Brief aerial skirmishes between goshawks and peregrine falcons ("Falco peregrinus") have been described but neither species is known to have killed one another in the wild. In Schleswig-Holstein, Germany, at least four small passerines species were recorded as nesting close to active goshawk nest, due to the incidental shelter that the fierce goshawks inadvertently provides from smaller raptors which are their main predators. Such raptors, including Eurasian kestrels, Eurasian sparrowhawks and long-eared owls, not only avoid goshawk activity where possible but also were found to have lower nest productivity any time they nested relatively close to goshawks per the study. A similar phenomenon, with goshawks inadvertently providing shelter to small passerines, has been recorded in North America as well.
Competition for northern goshawks can also come from mammalian carnivores. Martens, and to a lesser extent other weasels, are presumably one of their more major competitors as their diet often consists of similar prey primarily during spring and summer, tree squirrels and woodland birds, but little has been studied in terms of how the two types of predator effect each other. Most recorded interactions have been predatory, as the goshawk has been recorded preying on a dozen species, from the least weasel ("Mustela nivalis") to the stone marten ("Martes foina"). Northern goshawks have also been recorded as feeding on much bigger predators such as the red fox ("Vulpes vulpes"), the raccoon dog ("Nyctereutes procyonoides") and the striped skunk ("Mephitis mephitis"), but it is not clear whether these were actual kills, as many may be encountered as already dead carrion. Domestic carnivores are sometimes eaten, including dogs and cats, the latter of which has reportedly been taken alive by goshawks. The red fox is a surprisingly considerable competitor for resources with northern goshawks. It was found in Norway that goshawk numbers were higher when voles were at peak numbers, not due to voles as a food source but because foxes were more likely to eat the rodents and ignore grouse, whereas during low vole numbers the foxes are more likely to compete with goshawks over grouse as prey. A decrease of the fox population of Norway due to sarcoptic mange was found result in an increase of grouse numbers and, in turn, northern goshawks. In some areas, red foxes have been found to steal up to half of the goshawks’ kills.