Owls are birds belonging to the class Aves and the order Strigiformes.
What Is a Bird?
In biology, all living things are classified on a rank-based system of nomenclature in which related classes are grouped together based on shared descent from their nearest common ancestor. The common taxonomic rank is kingdom, phylum, class, order, family, genus, and species. Using this taxonomy, birds are ranked as thus:
Kingdom: Animalia (animals)
Phylum: Chordata (animals with a spinal cord)
Class: Aves (living and extinct birds)
How Are Owls Classified in the Animal Kingdom?
The class Aves is further divided into order, family, genus, and species. Using this taxonomy, owls are ranked as thus:
Order: Strigiformes (owl)
Family: Strigidae; Tytonidae (owls are divided into two families Strigidae, which are typical owls and Tytonidae, which are barn owls)
There are more than 250 species of owls located across the globe. [Konig]
Characteristics of the Class Aves
There are 9,600 living species in the class Aves. Animals in this class are characterized as warm-blooded, egg-laying vertebrates with feathers, a four-chamber heart, and forelimbs modified into wings. [Britannica]
What Makes an Owl a Bird?
Looking at the characteristics of a bird, we can further understand how an owl easily fits into this category.
Warm Blooded: Owls are warm-blooded, which means they have the ability to maintain a constant body temperature through metabolic means. Owls, in fact all birds, maintain a higher body temperature than mammals do at 1.87°C higher during rest and 2.43°C higher during the active phase. Owls have a normal body temperature of 39-40°C. When exposed to hot environments this body temperature can increase 3-4°C. It also rises during flight. [Taylor]
INTERESTING FACT: A bird keeps its brain cooler than the rest of its body maintaining it at 1°C below the temperature of its body.
Vertebrates: Owls are vertebrates, which means they have a backbone. Unlike the highly flexible, moving thoracic vertebrae of the human, the bird’s thoracic vertebrae is fused to help keep the body stiff during flight. The vertebrae in the neck are highly flexible, the owl being a perfect example. [HSU]
The flexible vertebrae in the neck of the owl gives it a great range of motion including the ability to turn the head nearly 270° in either direction. [John Hopkins]
Egg-Laying: All birds lay eggs including owls. The number of eggs laid will vary from species to species, but they usually lay more eggs than most diurnal raptors with the snowy owl laying between 3-11 eggs in a season depending on food supply. Owl eggs are also more spherical than any other bird group. [UM]
Feathers: Like all birds, owls have feathers. Owl feathers are generally larger than other species and have several unique characteristics that make them inaudible to prey. The noiseless flight of the owl can be credited to three physical attributes of its unique wing structure: the soft serrated edges of its leading wing, the flexible fringe on the trailing edge of the wing, and the soft downy feathers at the top of the wing. [Jaworski]
Unlike many birds with showy plumage, owl feathers are usually mottled shades to blend in with their surroundings to help them avoid predators and to make them less visible to their prey.
Benoit Dayrat; University of California Merced
Celebrating 250 Dynamic Years of Nomenclatural Debates
König C, Weick F (2008)
Owls: a guide to the owls of the world.
Second Edition. Robertsbridge: Pica Press.
Britannica Academic Edition
Taylor, C. Richard, Kjell Johansen, Liana Bolis, and Knut Nielsen. A companion to Animal physiology: papers from the Fifth International Conference on Comparative Physiology held at Sandbjerg, Denmark, July 22-26, 1980. Cambridge: Cambridge University Press, 1982. Print.
Henderson State University
Skeletal Adaptations of Birds in Flight
John Hopkins Medicine
OWL MYSTERY UNRAVELED: SCIENTISTS EXPLAIN HOW BIRD CAN ROTATE ITS HEAD WITHOUT CUTTING OFF BLOOD SUPPLY TO BRAIN
University of Michigan Bio Kids
Jaworski, J; American Physical Society
Vortex Noise Reductions from a Flexible Fiber Model of Owl Down