Smallest and Largest: The smallest owl in the world is the Elf Owl (Micrathene whitneyi), which is about 6.1 inches (16 cm) long, has a wingspan of 15 inches (38 cm), and weighs about 1.5 ounces (4g). The largest owls are the Great Gray Owls (Strix nebulosa) [which are about 33 inches (84 cm) long, have a wingspan of about 5 feet (152 cm), and weigh about 3 pounds (1450 g)], the Eurasian Eagle Owls (Bubo bubo) [which are about 28 inches (71 cm) long, have a wingspan of about 5.2 feet (160 cm), and weigh up to 9.8 pounds (4200 g)], and the Great Horned Owls (Bubo virginianus) [which are about 25 inches (63 cm) long, have a wingspan of about 5 feet (152 cm), and weigh about 4 pounds (1800 g)].

Eyes: Owls have a large head and large eyes that face forwards (unlike other birds, whose eyes are on the sides of their head). This eye placement gives them binocular vision and very precise depth perception. Also, there are circles of radiating feathers surrounding each eye, giving them a wide-eyed, alert look.

Owls cannot move their eyes within their sockets like we can. In order to look around, they have to move their entire head, which has a range of movement of about 270°.

Diet: Owls are carnivores (meat-eaters). Most are nocturnal and hunt at night. They use a keen sense of sight to find prey in the dark (owls see mostly in black and white). They have an acute sense of hearing which also helps in finding meals. Owls are stealth hunters; they can easily sneak up on their prey since their fluffy feathers give them almost silent flight. Owls hunt and eat rodents, insects, frogs, and birds. Owls eat smaller prey whole and larger prey in chunks. They regurgitate the inedible parts (including hair, teeth, bone, feathers, and insect exoskeletons) in oval-shaped pellets. The owl is at the top of the food web; it has no major predators.