One of the most fascinating mysteries of nature is that of migration, be it of birds or butterflies. What is it that brings birds back to the same location over and over? Is it a combination of cues? What would happen if those cues changed?
A recent discovery about homing pigeons, made by a group of Ornithologists has given some insight into this question. In a research article published in Scientific Reports by Nora Zannoni and her team, the chemicals that are responsible for providing odor cues have now been identified. For 40 years, scientists have been aware that the sense of smell is key to bird navigation but now the specifics are much clearer.
This group conducted experiments in 2017 and 2018 as part of the HOMING project (Hunting Organic Molecules in NaviGation). The project involved identifying chemicals and deriving olfactory or smell maps that would be the guiding mechanism for birds. A total of 174 pigeons were tagged with GPS loggers in these experiments.
The birds were housed at an aviary in rural Tuscany, which was designated as the “home.” Three different sites were chosen for releasing the birds for the navigational studies. The air was sampled by airplane flights from all three ecosystems that traveled at a height (180m) similar to that of the birds. The air was assessed all along the flying zone of these pigeons from the three sites of release to their “home.”
Calculations were made based on the wind and direction to determine the mixing of the volatile (airborne) chemicals that were in the air. The “home” was in a coastal area, so the types of chemicals would be different, as would the wind speeds. The birds were born in the aviary, and that air was the first air they had ever breathed and smelled. They would have a natural tendency to move in the direction of these smells. This multi-year study was completed and published recently, adding to the understanding of the role of volatile organic chemicals in the air in guiding homing pigeons back to their home.
Bibliography
Knight , Kathryn. “Disappearing Homing Pigeon Mystery Solved.” ScienceDaily, ScienceDaily, 30 Jan. 2013, www.sciencedaily.com/releases/2013/01/130130184147.htm.
Zannoni, Nora, et al. “Identifying Volatile Organic Compounds Used for Olfactory Navigation by Homing Pigeons.” Nature News, Nature Publishing Group, 28 Sept. 2020, www.nature.com/articles/s41598-020-72525-2.
