Do Birds Have a Sense of Smell?

Yes, birds do have a sense of smell—contrary to long-standing scientific belief that most birds rely almost exclusively on sight and hearing. While it was once widely assumed that birds were anosmic (lacking the ability to smell), modern research has clearly demonstrated that many bird species possess a functional olfactory system and use their sense of smell in meaningful ways. This revelation has reshaped our understanding of avian biology and behavior, particularly in species such as seabirds, vultures, and certain songbirds. The question do birds have a sense of smell is now answered with growing evidence from neurobiology, ecology, and field observation showing that olfaction contributes to survival strategies including finding food, recognizing kin, and navigating vast distances.

The Historical Misconception About Bird Olfaction

For much of the 20th century, ornithologists largely dismissed the idea that birds could smell. This assumption stemmed from early anatomical studies that noted relatively small olfactory bulbs in the brains of many common bird species, especially passerines like sparrows and finches. Because these brain regions are associated with processing smell in mammals, scientists extrapolated that birds must have limited or no olfactory capabilities.

This bias was reinforced by the observable dominance of vision and hearing in bird behavior—e.g., intricate visual courtship displays and complex vocalizations used in mating and territory defense. As a result, the notion that birds cannot smell became entrenched in textbooks and popular science writing.

However, this view began to shift in the late 20th century as researchers started investigating species that lived in environments where vision was less effective—such as dark burrows or open oceans. These studies revealed that some birds not only had larger-than-expected olfactory bulbs but also exhibited behaviors clearly guided by scent.

Bird Species Known to Use Smell

Not all birds use smell equally. Olfactory ability varies significantly across avian lineages, often correlating with ecological niche and evolutionary pressures. Below are key groups of birds known to rely on their sense of smell:

• Procellariiformes (Tubenoses): Albatrosses, petrels, and shearwaters have highly developed olfactory systems. These seabirds can detect dimethyl sulfide (DMS), a chemical released by phytoplankton when consumed by krill—a sign that food sources like fish and squid are nearby. They use this ability to locate prey over thousands of square miles of open ocean.
• New World Vultures: Turkey vultures (Cathartes aura) are famous for their ability to locate carrion by smell. Unlike most raptors, which rely on sharp vision, turkey vultures can detect ethyl mercaptan, a gas produced during decay, from great distances—even beneath forest canopies.
• Kiwis: These flightless birds from New Zealand have nostrils at the tip of their long beaks, an unusual trait among birds. Kiwis probe soil for invertebrates and appear to rely heavily on olfaction to find food in dark, dense forests.
• Pigeons and Doves: Some studies suggest that homing pigeons may use environmental odors as part of their navigational toolkit, especially when combined with magnetic fields and visual landmarks.
• Some Songbirds: Recent research indicates that certain passerines, such as European starlings and dark-eyed juncos, can distinguish between scents, possibly using them in mate selection or nest recognition.

How Bird Smell Works: Anatomy and Neurology

The avian olfactory system shares fundamental similarities with that of mammals. Airborne odor molecules enter through the nares (nostrils), bind to olfactory receptors in the nasal cavity, and send signals via the olfactory nerve to the olfactory bulb in the brain. From there, information is processed in higher brain centers.

What differs among bird species is the size and complexity of the olfactory bulb relative to overall brain volume. In tubenoses and vultures, the olfactory bulb is proportionally large. Genomic studies have further shown that these birds possess hundreds of functional olfactory receptor genes—some species have over 600, comparable to mammals known for keen smell like mice.

In contrast, birds like eagles and hawks, which rely primarily on vision, tend to have smaller olfactory bulbs and fewer olfactory receptor genes. This variation supports the idea that olfaction evolved in birds based on ecological needs rather than being uniformly absent.

Functions of Smell in Bird Behavior

Smell serves several critical functions in birds that utilize it:

1. Foraging and Food Detection

Seabirds exemplify how smell aids in locating food. A study published in Science showed that storm-petrels were attracted to experimental releases of DMS, confirming its role as a foraging cue. Similarly, turkey vultures outperform other scavengers in finding hidden carcasses when visibility is low, thanks to their olfactory sensitivity.

2. Navigation and Homing

The “olfactory navigation hypothesis” suggests that some birds, particularly pigeons, learn wind-borne odor maps during development and use them to determine direction. Experiments have shown that pigeons with impaired smell (via olfactory nerve lesions) exhibit reduced homing accuracy, especially under overcast skies when celestial cues are unavailable.

3. Social Recognition and Mate Choice

Emerging evidence shows that birds may use individual or colony-specific scents to recognize kin or assess potential mates. For example, crested auklets produce a citrus-like plumage odor during breeding season, which appears to play a role in pair bonding. In zebra finches, odor cues may help parents identify their chicks in crowded colonies.

4. Nest and Territory Identification

Birds nesting in burrows or dense vegetation—such as kiwis or some penguins—may use scent to locate their nests in darkness or low visibility. Antarctic prions, a type of petrel, return to their burrows at night and likely depend on smell to avoid entering the wrong nest.

Debunking Common Myths About Bird Senses

Several misconceptions persist about bird senses, particularly regarding smell:

• Myth: All birds have a poor sense of smell.
  Reality: While many birds do not rely heavily on olfaction, numerous species have excellent smell capabilities adapted to their environment.
• Myth: Birds navigate solely by the sun and stars.
  Reality: Navigation is multimodal. Smell, magnetic fields, landmarks, and even infrasound contribute to orientation in migratory species.
• Myth: Only scavengers and seabirds can smell.
  Reality: Even common backyard birds may have underappreciated olfactory abilities. Research continues to uncover subtle uses of scent in diverse taxa.

Implications for Conservation and Human Interaction

Understanding avian olfaction has practical implications:

• Conservation Efforts: Seabirds attracted to DMS may also be lured by pollutants or fishing bait scents, increasing bycatch risk. Conservationists are exploring scent-based deterrents or attractants to guide birds away from danger zones.
• Wildlife Rehabilitation: Rehabilitators working with kiwis or tubenoses should minimize human scent contamination, as strong foreign odors might deter parental care or cause stress.
• Birdwatching and Ethical Observation: Birders should be aware that perfumes, lotions, or food odors might influence bird behavior, especially in sensitive habitats like seabird colonies or nocturnal nesting areas.

How to Observe Olfactory Behavior in Birds

While you can’t directly observe a bird smelling, you can look for behavioral clues that suggest olfactory involvement:

• Watch turkey vultures flying low over forests—they’re likely sniffing for carrion.
• Observe seabirds like shearwaters circling over ocean patches with high biological activity; they may be following scent plumes.
• Note if kiwis or rails pause and move their beaks side-to-side near the ground—a possible indication of scent probing.
• Use caution when visiting nesting colonies: avoid strong scents and respect buffer zones to prevent olfactory disturbance.

Regional and Seasonal Variations in Olfactory Use

Olfactory reliance can vary by region and season. For instance:

• In polar regions, where visual cues are limited during long winters, birds like snow petrels may depend more on smell for navigation and foraging.
• During breeding seasons, scent-related behaviors (e.g., mate attraction via plumage odor) become more pronounced in certain species.
• Urban environments may alter natural scent landscapes, potentially interfering with birds’ ability to detect food or navigate using odor cues.

Bird Group	Olfactory Ability	Primary Use of Smell	Example Species
Tubenoses	Very High	Locating marine prey	Albatross, Storm-petrel
New World Vultures	High	Finding carrion	Turkey Vulture
Kiwis	High	Foraging in soil	North Island Brown Kiwi
Pigeons	Moderate	Navigation	Homing Pigeon
Most Passerines	Low to Moderate	Social recognition	Zebra Finch

Future Research and Technological Advances

Advances in genomics, neuroimaging, and chemical ecology are expanding our knowledge of avian olfaction. Scientists are now able to sequence olfactory receptor genes across bird species, map brain activity in response to odors, and model how scent disperses in different environments.

One promising area is the development of bio-inspired sensors based on tubenose olfaction, which could improve detection of underwater resources or environmental changes. Additionally, tracking devices equipped with environmental sensors are helping researchers correlate bird movements with real-time atmospheric chemistry.

FAQs About Bird Smell

Can parrots smell?

Parrots have relatively small olfactory bulbs and are not known to rely on smell. Their primary senses are vision and hearing, though they may detect strong odors.

Do birds smell predators?

There is limited evidence, but some birds may detect predator scents. For example, certain rodents emit odors that could alert ground-nesting birds.

Why do vultures have a good sense of smell but eagles don’t?

Vultures evolved to find hidden carrion, favoring olfaction, while eagles hunt live prey visually from the air, reducing selective pressure for smell.

Can birds smell humans?

Yes, especially species with strong olfaction. Human scents may affect nesting behavior or cause avoidance in sensitive species like seabirds.

Is smell important for bird migration?

It may be one of several tools. Pigeons and some seabirds likely use odor maps alongside magnetic and visual cues for orientation.

In conclusion, the answer to do birds have a sense of smell is a definitive yes—for many species, at least. Far from being irrelevant, olfaction plays a vital role in the lives of numerous birds, influencing how they feed, navigate, and interact socially. As research progresses, we continue to uncover the hidden dimensions of avian perception, reminding us that nature’s solutions are often more nuanced than they first appear.