in both but would seem to learn which patches were more likely to have food and subsequently forage more extensively around them. When the same biologists observed the foraging patterns on field mice and also voles, they similarly learned and showed a preference for the patches that held larger species over smaller ones. On evidence, though prey selection is largely opportunistic, rodents at risk of starvation in the Japanese studies were more likely to risk foraging in relatively open spots of the ground, so therefore would be preferentially selected by the Ural owls. Based on the Japanese studies, Ural owls seem to be able to improve their resource utilization patterns as they accumulate experience within their environment.Nishimura, K. (1991). Utilization of different prey type patches in the Ural owl (Strix uralensis): a sit-and-wait predator. Behavioral Ecology, 2(2), 99-105. Different studies in Japan showed that the Ural owls are capable of hunting prey that is hiding in shallow snow or near the snow’s surface during winter but voles hiding in the subnivean zone, ephemeral tunnels made under deep snow by the voles, are largely inaccessible to these owls. Surplus food may be stored at the nest or at nearby depots. The first verified record of scavenging on carrion was recorded when a Ural owl fed on the carcass of a roe deer (Capreolus capreolus), although an earlier record exists of a Ural owl visiting a wolf's kill (though it was not clear that the owl fed in that case).Krofel, M. (2011). Monitoring of facultative avian scavengers on large mammal carcasses in Dinaric forest of Slovenia. Acrocephalus, 32(148-149), 45-51. Mammals Voles, small-to-medium-sized rodents with characteristically short tails, are often considered the most significant portion of the diet in almost every part of the distribution. Generally, in several parts to the west of their range, the Ural owl is associated with two vole prey species in particular, field voles (Microtus agrestis) and bank voles (Myodes glareolus). These voles tend to be solitary and fairly widely dispersed but habituate to favorable habitats for the Ural owls, such as the opener margins of extensive forested areas, and can quite numerous when vole populations peak.Koskela, E., & YlÖnen, H. (1995). Suppressed breeding in the field vole (Microtus agrestis): an adaptation to cyclically fluctuating predation risk. Behavioral Ecology, 6(3), 311-315.Ylönen, H., Viitala, J., & Mappes, T. (1991). How much do avian predators influence cyclic bank vole populations?