"Owls are one of the only birds that can see the color blue."
The Strigiformes (Owls) are an order of birds of prey, comprising 200 extant species. Most are solitary, and nocturnal, with some exceptions (e.g. the Burrowing Owl). Owls mostly hunt small mammals, insects, and other birds, though a few species specialize in hunting fish. They are found in all regions of the Earth except Antarctica, most of Greenland, and some remote islands. Though owls are typically solitary, the literary collective noun for a group of owls is a parliament. The living owls are divided into two families, the typical owls, Strigidae, and the barn-owls, Tytonidae.
The smallest owl is the Elf Owl (Micrathene whitneyi), at as little as 31 g (1.1 oz) and 13.5 cm (5.3 inches). Some of the pygmy owls are scarcely larger. The largest owls are two of the eagle owls, the Eurasian Eagle Owl (Bubo bubo) and Blakiston's Fish Owl (Bubo blakistoni), which may reach a size of 60-71 cm (28.4 in) long, have a wingspan of almost 2 m (6.6 ft), and weight of nearly 4.5 kg (10 lb).