This is the largest of the two owl families that make up the order Strigiformes. The second family is Tytonidae (the barn owls).

The family Strigidae consists of three subfamilies: Striginae, Asioninae, and Surniinae.

Within those three subfamilies are 25 genera with approximately 220 different species.

These birds are found worldwide (with the exception of Antarctica and some islands) and in a variety of habitats. Those habitats range from the tundra to the desert, to the forests (boreal to rainforest) and cosmopolitan areas.

As previously mentioned, their diets can vary from insects to amphibians, snakes, lizards, and small rodents. Unlike other raptors that will pluck the feathers from their meals before eating, owls will eat everything and what isn’t digestible can usually be found within an owl pellet (such as bone, fur/feathers, and so forth–including banding tags of medium size mammals).

Within North America (US/Canada/Mexico) the following members of the family can be spotted:

Long-eared owl

Short-eared owl

Great horned owl

Snowy owl

Spotted owl

Barred owl

Great Gray owl

Boreal owl

Northern Saw-whet owl

Burrowing owl

Flammulated owl

Whiskered screech owl

Western screech owl

Eastern screech owl

Elf owl

Northern pygmy-owl

Ferruginous pygmy-owl

Northern Hawk owl

The main photography goal is to get a picture of every owl found within North America.

Reference: https://en.wikipedia.org/wiki/true_owl