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