GC–MS Reveals Sex-Linked Scents in Macaws' Feathers

Birds were long thought to have a poor sense of smell. But evidence has been compiled which shows that some birds, including parrots, can detect scents in the air. These scents may carry messages about who a bird is, whether it is ready to breed, and how good a partner it would make.

In a recent study, researchers looked at the variety of scent compounds found in the feathers of scarlet macaws. They wanted to know whether a bird's scent differs depending on whether it is male or female, young or old, or paired with a mate, and whether its feather odor is linked to how strong its immune system is. To find out, they collected the scent compounds using solid-phase microextraction (SPME) and analyzed them with gas chromatography–mass spectrometry (GC–MS). A paper based on this research was published in the journal Integrative Zoology.¹

How Much Do We Know About Parrots' Sense of Smell?

Although parrots have drawn a lot of attention and conservation work, scientists still know relatively little about how they live and behave in the wild. In particular, the role that smell plays in their lives remains largely a mystery.^2,3In fact, a recent review pointed out that research on how birds use scent and chemical signals has focused heavily on certain groups. Songbirds and their relatives make up more than 60% of the species studied so far, while many other kinds of birds have barely been looked at.⁴

It was only a few years ago that scientists first found signs that scarlet macaws have a working sense of smell, one that lets them pick up the scent of the fruits they usually eat.⁵However, it is still not clear how they use their sense of smell in other parts of their everyday lives.

What Does a Macaw's Scent Reveal About It?

The researchers collected five feathers from the back of the neck of 18 scarlet macaws (nine males and nine females) living at the Loro Parque Fundación in Tenerife, Spain. To gauge the strength of each bird's built-in immune defenses, they tested how well its blood could kill bacteria, using flow cytometry.¹

Males had noticeably more scent compounds, and a wider variety of them, than females. Their feathers also carried larger shares of certain types of compounds, some of which are known for fruity or grassy smells. Meanwhile, birds with a mate had larger shares of other types of compounds than single birds did. These patterns suggest that the scent of a macaw's feathers is linked to whether it's male or female and whether it has a partner. This means scent may play a role in courtship and communication, perhaps helping birds tell males from females and get along with one another. However, the researchers found no link between a bird's feather scent and either its age or the strength of its immune system.¹

“Overall,” write the authors of the paper,¹ “this study expands current knowledge of avian chemical communication in an understudied taxon and highlights the potential relevance of olfactory cues for understanding macaw social biology and welfare.”

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References

1. Espartosa, E.; Barja, I.; Martin, J. et al. Volatile Compounds in Feathers of the Scarlet Macaw (Ara macao) Reflect Sex and Pair-Bond Status. Integr Zool. 2026.DOI: 10.1111/1749-4877.70197
2. Nevitt, G. A. Olfactory Foraging by Antarctic Procellariiform Seabirds: Life at High Reynolds Numbers. Biol Bull. 2000, 198 (2), 245-253. DOI: 10.2307/1542527
3. Potier, S. Olfaction in Raptors. Zool. J. Linn. Soc. 2020, 189, 713–721. DOI: 10.1093/zoolinnean/zlz121
4. Alves Soares, T.; Caspers, B. A.; Loos, H. M. Volatile Organic Compounds in Preen Oil and Feathers - A Review. Biol Rev Camb Philos Soc. 2024, 99 (3), 1085-1099. DOI: 10.1111/brv.13059
5. Hernández, M. C.; Villada, A. M.; Barja, I. Onto the Sense of Smell in Macaws, Amazons and Toucans: Can They Use Volatile Cues of Fruits to Make Foraging Decisions? Integr Zool. 2023, 18 (4), 762-771. DOI: 10.1111/1749-4877.12694
6. Hagelin, J. C.Observations on the Olfactory Ability of the Kakapo Strigops habroptilus, the Critically Endangered Parrot of New Zealand. Ibis 2004,146, 161–164. DOI: 10.1111/j.1474-919X.2004.00212.x