Can Birds Smell? Yes, Many Species Have Functional Olfaction

Birds can smell, but their sense of smell varies significantly across species. While early ornithological studies assumed birds had a poor olfactory system, modern research confirms that many bird species possess a functional and sometimes highly developed sense of smell. This ability plays a crucial role in navigation, foraging, and social behaviors. The question can birds smell is best answered with nuance: yes, many birds can smell, and in some cases, they rely on it more than previously thought.

The Evolution of Understanding Avian Olfaction

For much of the 20th century, scientists operated under the assumption that birds were anosmic—lacking the ability to smell. This belief stemmed from limited anatomical evidence and a focus on vision and hearing as primary avian senses. Early dissections showed relatively small olfactory bulbs in many common bird species like pigeons and songbirds, reinforcing the idea that smell was negligible in bird behavior.

However, discoveries in the late 1900s began to challenge this view. In particular, studies on seabirds such as albatrosses and petrels revealed enlarged olfactory bulbs and complex nasal passages. These birds were found to detect dimethyl sulfide (DMS), a chemical released by phytoplankton when consumed by krill—a key food source. By following DMS plumes over vast ocean expanses, these birds can locate productive feeding grounds thousands of feet below the surface.

Species That Rely Heavily on Smell

Not all birds use smell equally. Some species have evolved a highly refined olfactory system adapted to their ecological niche:

• Procellariiformes (tubenoses): Albatrosses, shearwaters, and petrels have some of the most developed olfactory systems among birds. Their tubular nostrils enhance odor detection and are essential for long-distance foraging at sea.
• Vultures: Turkey vultures (Cathartes aura) are well-known for using scent to locate carrion. They can detect ethyl mercaptan, a gas produced during early decomposition, even beneath forest canopies.
• Kiwis: These flightless birds from New Zealand have nostrils located at the tip of their long beaks, allowing them to probe soil and sniff out invertebrates. Their olfactory bulbs are proportionally larger than those of most birds.
• Starlings and other passerines: Recent experiments show that European starlings use odor cues to assess prey quality and select nesting materials free of parasites.

How Bird Smell Works: Anatomy and Physiology

The avian olfactory system includes the nostrils (nares), nasal cavity, olfactory epithelium, and olfactory bulbs in the brain. When air enters the nares, odor molecules bind to receptor cells in the epithelium. Signals are then transmitted via the olfactory nerve to the brain for processing.

Research comparing hundreds of bird species has shown a strong correlation between the size of the olfactory bulb and reliance on smell. For example, nocturnal birds or those foraging in dark or complex environments tend to have larger olfactory bulbs. MRI scans of kiwi brains reveal that their olfactory regions occupy up to 50% more space relative to brain size compared to diurnal birds.

Myths and Misconceptions About Bird Senses

One widespread myth is that birds cannot smell human scent on their young, so people should never touch baby birds. In reality, most birds have limited olfactory capabilities and primarily recognize offspring through sight and sound. Touching a fledgling does not cause parental abandonment—this is a misconception rooted in folklore rather than biology.

Another common misunderstanding is that all birds navigate solely by sight and magnetic fields. While visual landmarks and magnetoreception are important, some migratory species may also use environmental odors as navigational cues, especially over familiar terrain.

Practical Implications for Birdwatchers and Researchers

Understanding that birds can smell enhances both scientific study and recreational birding. For instance:

• When placing feeders, avoid strong-smelling contaminants like insect repellents or perfumes, which might deter sensitive species.
• In field research, minimizing personal scent (e.g., wearing unscented clothing) may improve observation accuracy, particularly for shy or nocturnal birds.
• Educators should update curricula to reflect current knowledge about avian olfaction, moving beyond outdated assumptions.

Comparative Table: Olfactory Ability Across Bird Species

Species	Olfactory Bulb Size (Relative)	Primary Use of Smell	Scientific Evidence Level
Common Raven	Moderate	Locating carrion, social cues	High
Turkey Vulture	Very Large	Detecting decaying meat	Very High
Kiwi	Exceptionally Large	Foraging in soil	Very High
House Sparrow	Small	Limited; possible mate selection	Moderate
Rock Pigeon	Small	Minimal; navigation unlikely	Low
Sooty Shearwater	Large	Finding prey over open ocean	High

Ecological and Behavioral Roles of Smell in Birds

Smell contributes to several critical behaviors:

• Foraging Efficiency: Seabirds exploit chemical signatures of marine productivity. This allows them to optimize energy expenditure during long flights.
• Nest Defense and Mate Selection: Some birds may use scent to identify kin or assess genetic compatibility. Studies suggest that female zebra finches prefer males whose odor indicates immune system diversity.
• Navigation: Homing pigeons were once thought to rely only on sun compass and magnetic cues, but recent work suggests olfactory maps—learned associations between wind-borne odors and location—may play a role, especially near home.

Regional and Seasonal Variations in Olfactory Use

The importance of smell can vary by region and season. In tropical rainforests, where dense vegetation limits visibility, certain bird species may depend more on olfactory cues. Similarly, during breeding seasons, pheromone-like compounds in preen oil could influence mate attraction.

In urban areas, air pollution may interfere with avian olfaction. Nitrogen dioxide and particulate matter can mask natural scents, potentially disrupting foraging and communication in smell-sensitive species.

How to Observe Smell-Related Behaviors in Birds

Birdwatchers can look for signs that a species may be using its sense of smell:

• Observe head movements near the ground or in leaf litter (e.g., kiwis probing with nostrils forward).
• Note circling flight patterns downwind of potential food sources—common in vultures.
• Watch for selective picking of aromatic plants during nest building, suggesting antimicrobial benefits.

To increase chances of witnessing such behaviors, visit habitats where olfaction is likely critical: coastal zones for seabirds, forests with high decomposition activity for vultures, or nocturnal hotspots for kiwis (with proper permits).

Future Research and Technological Advances

Advances in neuroimaging, genomics, and chemical ecology are deepening our understanding of avian olfaction. Scientists are now identifying specific olfactory receptor genes in birds and mapping their expression across species. Portable gas analyzers allow researchers to correlate airborne chemical concentrations with bird presence and behavior.

Long-term monitoring projects may soon reveal how climate change affects odor landscapes—altering wind patterns, ocean productivity, and plant emissions—which in turn could impact birds reliant on olfactory cues.

Conclusion: Reassessing the Role of Smell in Birds

The answer to can birds smell is no longer a simple 'no'—it's a scientifically supported 'yes,' with important qualifications. While not all birds rely on smell, many do, and for some, it is a vital sensory tool. Recognizing this expands our appreciation of avian intelligence and adaptability. As bird enthusiasts, conservationists, and scientists, we must integrate this knowledge into education, policy, and observational practices.

Frequently Asked Questions

Can birds smell humans?

Most birds cannot distinguish individual humans by scent alone, though some large-brained species like crows may associate smells with danger or food sources.

Do birds use smell to find their nests?

Some evidence suggests homing pigeons may use olfactory cues as part of a navigational toolkit, but this remains debated. Most birds rely more on visual landmarks.

Is it true that touching a baby bird will make its parents reject it?

No. Most birds have poor smell and recognize chicks by sight and sound. Parental abandonment after human contact is extremely rare.

Which bird has the best sense of smell?

The turkey vulture and various tubenose seabirds like albatrosses are considered to have the most acute olfactory abilities among birds.

Can pet birds smell?

Yes, though domesticated species like budgerigars have reduced olfactory bulbs compared to wild relatives. They may still respond to strong odors related to food or smoke.