Owls do have noses, but they are structured differently than those of mammals. Like all other bird species, owls possess a pair of external openings called nares, which serve the function of a nose. These openings are the entry point for air into the respiratory system. The unique appearance of the owl’s face often makes these structures difficult to see, leading to the misconception that they do not exist.
The Anatomy of Owl Nostrils
The external openings that serve as an owl’s nostrils, the nares, are located on the upper part of the beak, known as the maxillary rhamphotheca. They are positioned at the base of the bill, sometimes within a fleshy area called the cere. The nares appear as small, slit-like openings rather than the large, forward-facing structures seen in many mammals.
In many owls, these openings are partially or entirely obscured by specialized feathers known as narial bristles. These stiff, hair-like feathers grow around the edges of the nares, helping to filter out dust and debris from the air before it enters the respiratory tract.
Research suggests these narial bristles may also have a sensory function. They contain specialized vibration-sensitive mechanoreceptors called Herbst corpuscles around their follicles. This indicates the bristles are vibrotactile, meaning they can sense movement or vibrations in the air immediately surrounding the beak.
How Owls Breathe
The nares are the initial point of entry for air, which then travels through the nasal cavity to the trachea. The mechanics of breathing in owls, and birds generally, differ significantly from those of mammals. Owls lack a muscular diaphragm, the sheet of muscle that mammals use to draw air into the lungs.
Instead of expanding and contracting lungs, owls utilize a system of air sacs connected to the lungs, which fill the chest and abdominal cavity. These air sacs act as bellows, creating pressure changes that move air through the respiratory system. This unique system ensures a continuous, unidirectional flow of oxygen-rich air across the respiratory surfaces.
This highly efficient flow allows for greater oxygen extraction from each breath compared to the two-way flow in mammalian lungs. The air sacs also hold a reserve of air, beneficial for high-energy activities like flight. While the nares are the standard entry point, an owl under stress or exertion may open its mouth to supplement its air intake.
The Sense of Smell in Owls
Since owls have nares, the question is whether they use them for olfaction (smell). All birds possess the necessary neuroanatomical structure for smell, the olfactory bulb. However, the size of this bulb relative to the rest of the brain is small in owls. This anatomical feature suggests that olfaction is not a primary sensory modality for these birds.
Owls rely overwhelmingly on their exceptional vision and highly developed auditory system for hunting and navigation. Their large eyes and asymmetrically placed ears are far more important in locating prey than any sense of smell. For a species that hunts primarily by sound and sight, a strong sense of smell is less necessary.
A small olfactory bulb does not mean a complete absence of the sense of smell. Studies have shown that some nocturnal bird species have relatively larger olfactory bulbs than their diurnal counterparts. The Great Horned Owl, for example, successfully hunts skunks, suggesting a high tolerance or limited perception of the skunk’s defensive spray. This behavior is cited as evidence of their poor sense of smell compared to most mammals.