This is the bird European nobles would use for hunting: the merlin, Falco columbarius. It's still used by some in the United States, a practice called falconry.
Merlins are members of Falconidae, the falcon family. They're commonly found over most of North America, and parts of Europe and Asia. They're winter visitors to Florida and points south. They're fierce, powerful hunters — they'll overtake their prey, mostly birds but also bats and large insects like dragonflies — in mid-flight at speeds of 30 mph or more. They'll also grab small mammals off the ground. Falconers harness the merlin's abilities to pick off game birds and other animals. The practice is highly regulated and not without its critics on various fronts. It's also not limited to falcons.
Merlins are on the small side as far as falcons go, with a body length of a foot or less but a wingspan that can exceed two feet. They vary in looks, depending on the region, but generally have a gray back that extends into the top of the head, a striped breast and belly, and a face that's dark and has a "handlebar moustache" look that extends downward from the eyes. The eyes are dark. They're similar to both peregrines and American kestrels, two other falcon species, but both those birds lack the merlin's prominent brown streaking. Kestrels also have more color about the head, while merlins are bulkier.
In the western hemisphere, the merlin's range extends from the northern reaches of Canada and Alaska, where they spend summer, southward to Ecuador, where they winter over. There's also year-round populations in the northern Rockies and along the northwest Pacific coast.
There are three races, or subspecies, of the merlin, each divided to an extent by geography and each with a somewhat different look. There's the black, the darkest of the three, from the northwest; the prairie; and the taiga, which has the widest distribution of the three. The taiga is the only merlin seen in the eastern United States.
Merlins are birds of the forest and fields but have demonstrated an ability to adapt to urban settings as their natural habitats are lost. Merlins are known to specialize, or prey on a single type of bird, usually what's most plentiful in a particular area. In some cases, it's song birds, in others, shore birds. In cities, it's the house sparrow.
Merlins don't build nests, but rather reuse those abandoned by other species, particularly crows and hawks. Clutches average four or five eggs, which take a month, give or take, of incubation before hatching. Both parents split the duty, but females will do most of the sitting. The hatchlings will be able to take their first flight in a month. In the meantime, mom stays with the kids while dad brings home the figurative bacon. They are monogamous through the season but most pick new partners the following year.
Other names for the merlin include lady hawk, because it was the bird of choice for European noblewomen who engaged in falconry, and pigeon hawk, because merlins in flight resemble the shape of a pigeon. As noted, they are members of Falconidae, the falcon family.