Introduction to Owls
Owls are a world-wide order of birds known as Strigiformes and the 216 species range in size from the tiny, sparrow size, Elf Owl to the Eurasian Eagle Owl which has a wing span of nearly 2 metres and can weigh almost 5kg. They are a group of predatory birds, characterised by large forward facing eyes surrounded by a facial disk of short stiff feathers and an upright posture. A large proportion of owls are nocturnal. They occupy an equivalent niche to the diurnal birds of prey such as hawks, falcons, eagles and buzzards but they are not actually related. The resemblance to the day time birds of prey is an example of convergent evolution, where both groups have independently evolved several features such as the hooked beak and talons. Owls are all very closely related to each other, much more so than, for instance, the diurnal raptors which include birds as dissimilar as vultures, secretary birds, falcons etc. Even so, owls are separated into two fairly distinct families.
The first family is the Tytonidae which is made up of 17 species of barn and grass owl, and one species of Bay Owl. Members of this family are quite distinct from other owls and possess several differences. The most obvious external ones being the heart-shaped rather than round facial disk, the longer skull and beak, longer legs, longer and more pointed wings and a forked tail. Grass Owls come from Africa, South East Asia and Australia and are very similar to Barn Owls but have longer legs.
All of the other 198 owls are in the family Strigidae.
The collective noun for owls is a “Parliament”.