In the British Isles, the tawny owl is the largest and most powerful year-around native owl, ahead slightly of the long-eared and barn owls. Therefore, the tawny owl may be considered an apex predator here (despite still being vulnerable occasionally to diurnal raptors and ground predators). However, since the tawny owl never colonized Ireland, here the long-eared owl is the largest year-around owl (in these island much larger owls are very rare winter visitors, in the case of the snowy owl (Bubo scandiacus) or are probably accidentally introduced by humans, as is likely the Eurasian eagle-owl). However, in much of mainland Europe and elsewhere, tawny owls potentially overlap with larger owls and, depending on habitat composition and prey accessibilities, may be considered more correctly a mesopredator. Mainly in parts of northern and eastern Europe, tawny owls sometimes co-exist with their larger cousins, Ural owls. The Ural owl has generally similar nesting and feeding habits but tends to occur in slightly different habitats. Generally, the Ural is more broadly adaptive to taiga and similarly conifer based forests than are tawny owls and is also somewhat more likely to be active during daylight. In eastern Europe, the Ural species tends to occur more so at higher elevation in montane forest such as the Carpathian Mountains, especially those with extensive old growth of beech trees, while the tawny owls tend to occur at lower elevations and more mixed forest with fewer glades in these areas. A relatively low territory overlap of 13.3% was detected in Slovakia between tawny and Ural owl territories due to their differing habitats. Depending on range, the prey sizes taken by tawny owls tend to be considerably smaller than those selected by the more powerful Ural owl, with the latter's mean prey sizes averaging from 31 to 50% larger. However, the food niche breadth is up to two and a half times greater in the tawny than in the Ural owl. The Ural owl tends to dominate interspecific conflicts with tawny owls. On the contrary, in at least one case a tawny owl was observed to fiercely attack and drive off a Ural owl (although it may not be ruled out that this was a case of mobbing). A third and much larger still Strix species, the great grey owl, differs considerably in almost all respects of its life history from tawny owls. The great grey is adapted to taiga and other conifer based forests, both open and enclosed, and relies almost exclusively on voles for food. Almost cathemeral in activity, the great grey species may nest in a broad variety of situations in the boreal habitat but never utilizes tree cavities as does the tawny. Due to the latter species' specialization, the tawny owl is spared from any known ecological interactions with the great grey owl.