The easiest way to identify a Kestrel is to see if it hovers in one spot, as no other British bird of prey does this. In addition, look for pointed wings and a long tail. Typically the brown coloring is redder than other birds of prey and contrasts with black outer wings.
Mature white-tailed eagles are easily identifiable by their short, white tail feathers. However, if you come across an immature white-tailed eagle, look at the bird's shape, with the expansive wings, and outer primary feathers that seem to extend further out, as well as the big head and a beak that protrudes forward.
Peregrines seen from above have a dark appearance, while underneath they are pale colored. They beat their wings in a quick, shallow motion. The white chest is quite distinctive, wings are pointed and the short tail feathers taper to form an anchor shape.
Like a Kestrel, the Merlin has pointed wings but it is smaller, with a short tail and the plumage is darker. The Merlin beats its wings in a quick, shallow motion like the Peregrine and males have a black tip on the tail.
The tawny owl has a distinctive silhouette with a large and rounded head and completely dark eyes, unlike other British brown owls.