I am currently down in Cumbria staying with family and last week we were treated to a sighting of this Barn Owl out hunting an hour before sunset. After the encounter I was curious to why the species behave differently on Mull to the Barn Owls in Cumbria.
In my experience the Barn Owls on Mull are almost entirely nocturnal, with records of crepuscular hunting in the summer when there is little darkness. One theory to this is that there are more diurnal hunting raptors on Mull, from the small Kestrels to the huge White-tailed Eagles, and they are all a threat to Barn Owls through predation and competition when they choose to be active in good light.
There will be other theories and many more questions, which helps keeps us curious to the dynamic wonders of nature.