Foraging behavior of Ural owls (Strix uralensis) in a patchy environment: The importance of acquired information

How the allocation of searching investiment by Ural owls (Strix uralensis) in a patchy and fluctuating environment is affected by prior information was experimentally studied. The owls searched among four patches, two with prey and two without prey. During the five days, the positions of two prey patches were randomly assigned daily (random treatment) and for the other five days, they were fixed (fixed treatment). In experiment I, the sequence of treatments was from random to fixed. In experiment II, the sequence of treatments was reversed. The choice of prey present patch was affected by acquired information which owls acquired during one night (short term), a treatment period (medium term), and throughout the experiment run (long term). They predicted the positions of the prey patches, to some extent, in the first choice in one night in the fixed treatment by the experience of previous days. The searching time per visit was also affected by previous information. Owls searched prey patches longer than empty patches. In the random treatment, the giving up time in prey patches was variable, while in the fixed treatment, it was longer and fixed. Although owls could use information on the environment where they had searched to make a decision of foraging behavior, they were not able to choose prey patches accurately. The information which was acquired during the treatment period and throughout the experiment run affected the gain from prey. The changes in gain were not caused by the encounter rate but by the proportion of attack success.