In order to look for their prey, owls

The given blank can be filled with that the owls turn their head.

Explanation:

In spite of offering the impression of exhibiting a thick neck due to the plumage, the owls possess a very thin and articulated neck. They possess much more mobile vertebrae in comparison to the general vertebrae witnessed in mammals.  

In supplementation to the cervical spine being produced by exceptionally flexible vertebrae, these birds still possess about thirteen vertebrae in the neck, while the mammals like humans have only seven. All this leads to a tremendous tendency of the species to be attentive to the movements taking place around it.  

This tendency in combination with improved hearing and excelled vision makes the owl an excellent hunter.