even when prey populations decrease. Apart from the great grey species, like the Ural, most species in the Strix genus of owls are both highly territorial and non-migratory.Lundberg, A. (1979). Residency, migration and a compromise: adaptations to nest-site scarcity and food specialization in three Fennoscandian owl species. Oecologia, 41(3), 273-281. Territories are generally maintained with songs, most often uttered by the male of the resident pair. This is quite the norm for owls in almost every part of the world. Due probably to its natural scarcity, very few firsthand accounts are known of territorial fights between adults but they presumably occur as Ural owls can be quite aggressive owls (or are at least in the context of protecting their nests). However, according to a study in southern Poland, Ural owls are generally less aggressive in the non-breeding seasons than are tawny owls to other owls and may be slightly tolerant of smaller owl species on their home range while the tawny is less so. That the Ural is slightly less aggressively territorial than the tawny owl is also supported in a study from Slovenia when tawnys had more spirited calls to recorded calls and launched more aggressive attacks to the taxidermied specimens of Ural, boreal and owls of their own species than did the Ural owls to any of the same stated stimuli. As for movements, as opposed to the sedentary adults, immatures may wander distances of up to about . An occasional individual may wander straggle even further and remain for some time in a wintering area. A small number of straggling young Ural owls may occur irregularly down in southeastern Europe outside of the typical range of the species. Some circumstantial evidence was reported of Ural owls moving downhill in mountains in Japan when snowfall was heavy. Siberian population shows somewhat southward movements in severe winters, as the number of prey animals plummets and the owls themselves face risk of freezing. Dietary biology This is a fairly powerful species of owl. However, like owls of nearly all sizes, mostly it prefers to take small prey relative to itself, especially small mammals. In a great majority of dietary studies, somewhere between 50 and 95% of the food is mammalian. Prey consists mostly of various species of rodent, though shrews and, locally, moles can be a regular food source as well. In additional, any variety of small mammal, to the