In the female, the ear opening averages 31.7 mm (1.25 in) on the right and 27.4 mm (1.08 in) on the left and, in males, averages 26.8 mm (1.06 in) on the right and 24.4 mm (0.96 in) on the left. , Eagle-owls are distributed somewhat sparsely but can potentially inhabit a wide range of habitats, with a partiality for irregular topography. Grimmett, R., Roberts, T. J., Inskipp, T., & Byers, C. (2008). In some European birds, the iris is a bright reddish, blood-orange colour but then in subspecies found in arid, desert-like habitats, the iris can range into an orange-yellow colour (most closely related species generally have yellowish irises, excluding the Indian eagle-owl).  All Eurasian eagle-owl nests in the largely forested Altai Krai region of Russia were found to be on the ground, usually at the base of pines. Bull, Evelyn L. and James R. Duncan. Females were less likely to be aggressive to mounted specimens and did not seem to vary in their response whether exposed to the specimens with or without the puffed up white patch.  More commonly, the female flies off and abandons her nest temporarily, leaving the eggs or small nestlings exposed, when a human approaches it.  With a total range in Europe and Asia of about 32 million square kilometres (12 million square miles) and a total population estimated to be between 250 thousand and 2.5 million, the IUCN lists the bird's conservation status as being of "least concern".  In a study from Spain, areas primarily consisting of woodlands (52% of study area being forested) were preferred with pine trees predominating the oaks in habitats used, as opposed to truly mixed pine-oak woodland. In a related, slightly disturbing note, an owl fossil named Orinmegalonyx oteroi shows an owl that stood three feet tall. Therefore, Spanish conservationists have recommended to boost education and stewardship programs in order to protect eagle-owls from direct killing by local residents. The feathers of the upper breast generally have brownish-black centres and reddish-brown edges except for the central ones which have white edges.  The Indian eagle-owl (B. bengalensis) was also considered a subspecies of the Eurasian eagle-owl until recently, but its smaller size, distinct voice (more clipped and high-pitched than the Eurasian), and the fact that it is largely allopatric in distribution (filling out the Indian subcontinent) with other Eurasian eagle-owl races has led to it being considered a distinct species.  The snowy owl is obviously distinctive from most eagle-owls, but during winter the palest Eurasian eagle-owl race (B. b. sibiricus) can appear off-white.  Tree holes being used for nesting sites are even more rarely recorded than nests constructed by other birds. Flint, V. E., Boehme, R. L., Kostin, Y. V., Kuznetsov, A.  This is contrary to the indication that ground nests are selected only if rocky areas or other bird nests are unavailable, as many will utilize ground nests even where large bird nests seem to be accessible. The number is expected to increase due to the growth of the European rabbit population in Helsinki.  The Indian species is smaller with a bolder blackish facial disc border, more rounded and relatively smaller wings and partially unfeathered toes.  It will usually select obvious topographic features such as rocky pinnacles, stark ridges and mountain peaks to use as regular song posts. This species is both the largest owl found in Africa and the world's largest owl to occur in the tropics.  Many feel that the eagle-owl would be classified as an "alien" species.  Heimo Mikkola reported the largest specimens of eagle-owl as having the same upper body mass, 4.6 kg (10 lb), as the largest Blakiston’s fish owl and attained a length of around 3 cm (1.2 in) longer. After this point, the female gradually resumes hunting from both herself and the young and thus provides a greater range of food for the young.  The chicks can walk well at five weeks of age and by seven weeks are taking short flights. In elevated nest sites, chicks usually wander out of the nest at 5 to as late as 7 weeks of age, but have been recorded leaving the nest if the nest is on the ground as early as 22 to 25 days old.  They open their eyes at 4 days of age. The chin and throat are white with a brownish central streak.  Nearly as important in territorial behaviour as vocalization is the white throat patch.  On the contrary, the race still found together with the Pharaoh eagle-owl in the wild (B. b. interpositus) in the central Middle East has been found to interbreed in the wild with the Pharaoh eagle-owl, although genetical materials have indicated interpositus may itself be a distinct species from the Eurasian eagle-owl, as it differs from the nominate subspecies of the Eurasian eagle-owl by 2.8% in mitochondrial DNA. they are absent from humid rainforest in Southeast Asia, as well as the high Arctic tundra, both of which they are more or less replaced by other variety of Bubo owls. These are dotted along the outer edges of the eagle-owl's territory and they are visited often but only for a few minutes at a time. During the incubation period, the female is brought food at the nest by her mate. Several potential sites may be presented, with the female selecting one. There are also concerns about a lack of genetic diversity of the species in this part of Germany.  In Asia Minor, they are found broadly in Georgia, Azerbaijan and somewhat so in western and southern Turkey but is quite sporadic in distribution overall in Turkey.  Apparently, the German reintroductions have allowed eagle-owls to repopulate neighbouring parts of Europe, as the breeding populations now occurring in the Low Countries (Netherlands, Belgium and Luxembourg) are believed to be the result of influx from regions further to the east.  Essentially, Eurasian eagle-owls have been found living in almost every climatic and environmental condition on the Eurasian continent, excluding the greatest extremities, i.e. Across from its south German range, this species range is nearly continuous into the Czech Republic, Slovakia, northern and eastern Hungary and very spottily into Poland. Three fish owls appear to overlap in range, the brown (Ketupa zeylonensis) in at least northern Pakistan, probably Kashmir and discontinuously in southern Turkey, the tawny (K. flavipes) through much of eastern China and Blakiston's fish owl in the Russian Far East, northeastern China and Hokkaido.  The discrepancy of aggressiveness at the nest between the Eurasian eagle-owl and its Nearctic counterpart may be correlated to variation in the extent of nest predation that the species endured during the evolutionary process. (1993).  The Cape eagle-owl (B. capensis) appears to represent a return of this genetic line back into the African continent, where it leads a lifestyle similar to Eurasian eagle-owls albeit far to the south. The legs and feet (which are feathered almost to the talons) are likewise marked on a buff ground colour but more faintly. Besides the Kurils, the farthest eastern part of the range for this species is in Magadan in the Russian Far East.  The plumage coloration across at least 13 accepted subspecies can be highly variable. Raucous barks not unlike those of ural owls or long-eared owls have been recorded but are deeper and more powerful than those species’ barks. Due to its predatory abilities, many, especially those in the press, have expressed alarm of their effect on "native" species. Tawny and brown fish owls are both slightly smaller than co-occurring Eurasian eagle-owls and Blakiston’s fish owls are similar or slightly larger than co-occurring large northern eagle-owls.  The male continues to bring prey, leaving in on or around the nest, and the female feeds the nestlings, tearing up the food into suitably-sized pieces.