Eagle Owl

Bubo bubo

The Eagle Owl belongs to the order of Strigiformes. It is the largest owl species in the world and is only slightly smaller than the Golden Eagle.

Description
Main colour below is brownish-black, upperparts darker. At present there are 14 known subspecies, but likely even more (as genetic analyses from Asia are lacking). Subspecies differ from native Central European species in terms of size and colouring. Main characteristics include the red eyes and long ear tufts. Females are significantly larger than males. There is a marked increase in size and weight from southwest to northeast (Carl Bergmann, anatomist and physiologist, first described in 1847 the characteristic increase in weight and size among individuals in a species going from warmer to cooler areas, the so-called Bergmann Rule). Size ranges from 60 to 75cm with a wingspan of 160 to 188cm. In Norway, females with a weight of up to 4200g have been documented, while the heaviest recorded female specimen in Central Europe reached 3200g. Beak is dark brown to black. The call of the male Eagle Owl is a muted "oo-hoo" (the German name for Bubo bubo is in fact onomatopoeic: "Uhu") and a lengthy barking "rhäev"; February, beginning of March and October are the most likely times to hear the call. Females sing at a higher pitch and less frequently.

Distribution
Bubo bubo is native to all of Asia, Africa, parts of North America and Europe; only the British Isles lack this species. The Eagle Owl prefers open plains alternating with forest environments as hunting grounds. Nests are build in alcoves on cliffs, mountain crags, but also occasionally in buildings. In the Donau-Auen National Park, the Eagle Owl may be found on the south banks of the Danube.

Endangerment and Conservation Status
In Austria, the Eagle Owl is categorized as potentially endangered to endangered; in Lower Austria, it is classified as potentially endangered.

Behaviour
Eagle Owls lay their eggs from March to July; eggs are hatched after 30 days. Fledgling young are fed a diet of small mammals – in particular mice, rats, rabbits and hedgehogs – and birds (up to hare size) for five months. Eagle Owls may nest again from April to September – up to three generations per year are possible.

Special Characteristics
Under ideal conditions, some healthy eagle owls may reach a very old age. In the wild, the oldest known tagged Eagle Owl was 27 years old. Unfortunately, the mortality rate for fledglings is very high at around 70%. Natural predators of Eagle Owls include martens and foxes, which often disturb and plunder the owl's nesting sites. The Bubo bubo can fly with loads of up to two-thirds of its own body weight, carrying prey such as ducks, cats and even fawns.