The name kestrel, is given to several different members of the falcon

Falcon

A falcon is any species of raptor in the genus Falco. The genus contains 37 species, widely distributed throughout Europe, Asia, and North America....

 genus, Falco. Kestrels are most easily distinguished by their typical hunting behaviour which is to hover at a height of around 10 – over open country and swoop down on prey, usually small mammals, lizards or large insects. Other falcons are more adapted to active hunting on the wing. In addition, kestrels are notable for usually having much brown in their plumage.

Kestrels require a slight headwind in order to hover, hence a local name of Windhover for Common Kestrel

Common Kestrel

The Common Kestrel is a bird of prey species belonging to the kestrel group of the falcon family Falconidae. It is also known as the European Kestrel, Eurasian Kestrel, or Old World Kestrel. In Britain, where no other brown falcon occurs, it is generally just called "the kestrel".This species...

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Plumage often—but unusually for falcons—differs between male and female, and (as is usual with monogamous raptor

Bird of prey

Birds of prey are birds that hunt for food primarily on the wing, using their keen senses, especially vision. They are defined as birds that primarily hunt vertebrates, including other birds. Their talons and beaks tend to be relatively large, powerful and adapted for tearing and/or piercing flesh....

s) the female is slightly larger than the male.