For years, scientists believed that hummingbirds lacked a sense of smell due to their tiny olfactory bulbs.
But a recent study by researchers at the University of California, Riverside, has shattered this long-held belief1. The study, titled “What is that smell? Hummingbirds avoid foraging on resources with defensive insect compounds,” has revealed that these tiny birds can indeed smell, and their sense of smell plays a crucial role in their foraging behavior.
Here are five of the key findings that shed light on the surprising olfactory capabilities of hummingbirds:
1. Hummingbirds Steer Clear of Insect Chemicals
One of the key findings of the study is that hummingbirds actively avoid feeders treated with insect-derived chemicals, such as those produced by ants and other insects as a defense mechanism. This behavior suggests that hummingbirds can detect and recognize potentially harmful substances, allowing them to steer clear of danger while foraging for nectar.
In the study, researchers conducted experiments where they allowed more than 100 hummingbirds to choose between two feeders: one containing plain sugar water and the other containing sugar water mixed with various insect-derived chemicals.
The results were striking – the hummingbirds consistently avoided the feeders treated with chemicals like formic acid (produced by some Formica ants) and an attraction chemical secreted by Argentine ants.
2. Honeybee Scent Doesn’t Deter Hummingbirds
Interestingly, the study revealed that hummingbirds did not show any aversion to the scent left behind by honeybees on flowers.
This selective avoidance indicates that hummingbirds can differentiate between harmless and potentially harmful scents, fine-tuning their foraging strategies accordingly.
3. Hummingbirds Are Completely Unfazed by Unfamiliar Scents
To ensure that the hummingbirds were reacting specifically to the insect-derived chemicals and not just any new scent, the researchers introduced an unfamiliar scent (ethyl butyrate, which smells like Juicy Fruit gum).
The hummingbirds showed no aversion to this novel scent, suggesting that their avoidance behavior is specifically targeted towards potential threats.
4. Research Was Done as Accurately as Possible
To ensure the accuracy of the findings, the researchers:
- Conducted trials over short periods to minimize the chance of the same bird visiting multiple times
- Alternated feeder positions to prevent positional bias
- Recorded the number and duration of feeding visits to each feeder
- Analyzed data using advanced statistical methods, including linear mixed models and effect size calculations
These steps allowed the researchers to quantify the strength of the hummingbirds’ responses to the chemical cues.
5. Implications of the Study: Challenging Previous Beliefs
This study challenges the long-held belief that hummingbirds have a poor sense of smell. The findings suggest that these tiny birds possess a keen ability to detect and react to chemical cues in their environment.
This discovery has important implications for understanding the ecological interactions between hummingbirds and their food sources, as well as their potential adaptations to avoid predation risk or suboptimal foraging conditions.
Hummingbirds Can Smell Better Than We Thought
So the next time you see a hummingbird zipping around your garden, remember that there’s more to these tiny birds than meets the eye. They’ve got hidden talents and abilities that we’re just starting to discover, and that’s what makes them so amazing to watch and learn about.
Source
- https://link.springer.com/content/pdf/10.1007/s00265-021-03067-4.pdf
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Davin is a jack-of-all-trades but has professional training and experience in various home and garden subjects. He leans on other experts when needed and edits and fact-checks all articles.