Do Birds Have a Sense of Smell? Yes, and It Varies by Species

Yes, birds do have a sense of smell, though it varies widely across species. For decades, the myth persisted that birds were anosmic—unable to detect odors—but modern research into avian olfaction has thoroughly debunked this notion. Today, scientists recognize that many bird species rely on their sense of smell for critical survival tasks such as navigation, foraging, and social communication. The question do birds have sense of smell is not only scientifically valid but increasingly central to understanding avian behavior and ecology. In fact, certain groups like tubenosed seabirds (Procellariiformes) possess exceptionally well-developed olfactory systems, allowing them to detect food sources over vast oceanic distances.

Historical Misconceptions About Bird Olfaction

For much of the 20th century, ornithologists largely dismissed the idea that birds could smell. This belief stemmed from early neuroanatomical studies showing that the olfactory bulbs—the brain regions responsible for processing smells—were small in most birds compared to mammals. Pioneering anatomist John E. King, in the 1960s, reinforced this view by categorizing birds as microsmatic (having a weak sense of smell). As a result, generations of researchers focused almost exclusively on vision and hearing when studying bird behavior.

However, anecdotal evidence from field biologists suggested otherwise. Observations of turkey vultures (Cathartes aura) locating carrion hidden beneath forest canopies hinted at an underappreciated olfactory ability. It wasn’t until controlled experiments in the 1970s and 1980s that these suspicions were confirmed. Researchers like Dr. Kenneth C. Stager demonstrated that turkey vultures could reliably find decaying meat even when visual cues were blocked, proving they used olfaction as a primary detection method.

Biological Basis of Avian Smell

Birds possess functional olfactory receptors encoded by olfactory receptor (OR) genes. Genomic studies show that different bird lineages have varying numbers of OR genes, which correlates with their ecological needs. For example, kiwis (Apteryx mantelli), nocturnal ground-dwelling birds native to New Zealand, have some of the largest olfactory bulbs relative to brain size among birds. They use their keen sense of smell to probe soil for invertebrates, often detecting prey before seeing or hearing it.

In contrast, songbirds like sparrows and finches have smaller olfactory bulbs and fewer OR genes, suggesting a reduced reliance on smell. Yet even in these groups, recent studies indicate olfaction plays a role in nest recognition and predator avoidance. A 2021 study published in Proceedings of the Royal Society B found that dark-eyed juncos altered their nesting behavior in response to chemical cues from predators, indicating a functional olfactory threat detection system.

Bird Group	Olfactory Bulb Size	Key Olfactory Behaviors	Number of OR Genes (approx.)
Tubenosed Seabirds (e.g., albatrosses, petrels)	Very large	Locating food over oceans, homing	~600
Kiwis	Large	Foraging in soil, mate selection	~500
Vultures	Moderate to large	Carrion detection	~400
Songbirds (Passerines)	Small	Nest recognition, predator cues	~200–300
Pigeons	Small to moderate	Homing navigation	~250

Ecological Roles of Smell in Birds

The function of smell in birds extends beyond mere food detection. Among seabirds, olfaction supports long-distance navigation. Species like the Antarctic prion (Pachyptila desolata) are attracted to dimethyl sulfide (DMS), a compound released by phytoplankton when consumed by krill. By following DMS gradients, these birds efficiently locate productive feeding zones across thousands of square kilometers of open ocean.

In addition, smell contributes to social interactions. Some petrel species use individual-specific scent profiles to identify mates and offspring in crowded breeding colonies. This is particularly important in burrow-nesting species where visual identification is limited. Similarly, crested auklets (Aethia cristatella) emit a tangerine-like odor during courtship, which appears to influence mate choice—an unusual example of pheromone-like signaling in birds.

Smell and Migration: Do Birds Use Odors to Navigate?

One of the most compelling applications of avian olfaction is in navigation. The “olfactory navigation hypothesis” suggests that homing pigeons (Columba livia) use environmental odor cues carried by winds to build mental maps of their surroundings. Experiments dating back to the 1970s showed that pigeons with impaired olfaction were significantly worse at returning home from unfamiliar locations.

While geomagnetic and solar cues also play roles in orientation, olfactory information may provide fine-scale spatial detail. For instance, pigeons might associate specific scent combinations—such as pine resin, seawater, or agricultural volatiles—with particular directions or landmarks. However, this mechanism remains debated, and its effectiveness likely depends on wind patterns, landscape complexity, and prior experience.

Practical Implications for Birdwatchers and Conservationists

Understanding that birds can smell has real-world implications for both recreational birding and wildlife management. For example, using scented sunscreen or perfumes near sensitive species could inadvertently alter their behavior. In conservation settings, olfactory cues are being explored as tools to attract endangered birds to safe habitats or deter them from dangerous areas.

Birdwatchers should consider minimizing strong odors when observing species known to rely on smell, especially in enclosed environments like blind boxes or coastal cliffs where seabirds breed. Additionally, researchers deploying camera traps or nest monitors now take care to de-scent equipment with odor-neutral cleaners to avoid influencing animal behavior.

Debunking Common Myths About Bird Senses

• Myth: Birds rely only on sight and sound.
  Reality: While vision and hearing are dominant in many species, smell plays a significant role in others, particularly those active at night or in low-visibility environments.
• Myth: All birds have poor olfactory abilities.
  Reality: Olfactory capacity varies dramatically; tubenosed seabirds and kiwis rival some mammals in sensitivity.
• Myth: Smell isn't important for bird migration.
  Reality: Evidence supports olfactory input in homing mechanisms, especially in pigeons and possibly other long-distance travelers.

How to Observe Olfactory Behavior in Birds

While you can’t directly observe a bird smelling, there are behavioral clues that suggest olfactory engagement:

1. Head movements during foraging: Kiwis and woodcocks bob their heads while probing soil, possibly sampling air currents near the ground.
2. Approaching from downwind: Vultures circling and descending toward a carcass often approach from the direction opposite the wind, indicating they’ve detected odor plumes.
3. Sniffing motions: Some petrels and shearwaters lower their bills close to the water surface while flying, a behavior linked to detecting DMS.
4. Delayed reactions to hidden bait: In experimental setups, birds may ignore visible food but later return to concealed, odorous items, suggesting memory of scent trails.

To test this in your own backyard, try placing two identical feeders—one with unscented seed and one laced with a mild, natural attractant like crushed anise or orange peel (avoid artificial fragrances). Monitor visitation rates over several days to see if certain species show preference, keeping in mind ethical guidelines against altering natural diets.

Future Research and Technological Advances

Advances in genomics, neuroimaging, and chemical ecology are transforming our understanding of avian olfaction. Portable gas chromatography devices now allow scientists to map volatile organic compounds in bird habitats, linking scent profiles to foraging success. Functional MRI studies on conscious birds remain rare but hold promise for revealing how odor information is processed in real time.

Additionally, citizen science projects are beginning to incorporate olfactory observations. Platforms like eBird could eventually include fields for noting wind direction, scent presence, or unusual behaviors potentially tied to smell, enriching datasets for future analysis.

Frequently Asked Questions

Do all birds have a sense of smell?

No, not all birds have equally developed olfactory systems. While every bird has some degree of olfactory capability, species like kiwis, vultures, and albatrosses have highly refined senses of smell, whereas many passerines rely less on olfaction.

Can birds smell humans?

Yes, birds can detect human scent, especially species with strong olfactory abilities. Strong perfumes, lotions, or food residues on clothing may influence how close birds approach, particularly in nesting or feeding contexts.

Why did people think birds couldn’t smell?

This misconception arose from early anatomical studies that emphasized brain structure without considering behavior. Since many birds have small olfactory bulbs, scientists assumed smell was unimportant, overlooking ecological and behavioral evidence.

Do birds use smell to find their nests?

Some species do. Burrow-nesting seabirds like petrels use individual scent signatures to locate their nests in dense colonies. Even pigeons may use environmental odors as part of their homing strategy.

How can I minimize my scent while birdwatching?

Avoid using scented products before heading out. Wear clean, odor-free clothing stored away from smoke or detergents with strong fragrances. When approaching sensitive areas, stay downwind of birds whenever possible.