Owls are actually able to see the color blue just fine and in fact some birds can see ultraviolet colors which even humans cannot see. The keen color vision of birds like owls is useful when trying to choose a mate or even looking for food.

Although it is true that owls can see the color blue, they tend to have worse color vision than other birds like hawks and eagles. There are many different kinds of birds which have feathers that are prominently colored with blue and other birds need to be able to see it for mating purposes.