A new study has shown that, contrary to what ornithologists believe, hummingbirds are able to recognize odors. In particular, they use their sense of smell to watch out for dangerous insects, according to an article in the scientific journal Behavioral Ecology and Sociobiology.
“This is the first clear evidence that hummingbirds use their sense of smell to navigate and avoid contact with potentially dangerous insects near flowers or other sources of nectar,” said Evin Rankin, one of the study authors and an assistant professor at the University of California, Riverside.
Only a handful of feathered birds – such as vultures and other scavengers – can recognize odors and use their sense of smell to find food, relatives or other targets. Rankin and her colleagues found that hummingbirds have such abilities. Previously, scientists believed that these birds looked for flowers, whose nectar they feed on, solely with the help of vision.
Recently, amateur naturalists have noticed that members of many hummingbird species consciously avoid contact with flowers near or inside which certain types of insects are present. This led Rankin and her colleagues to the idea that birds can smell these invertebrates and avoid contact with them.
To test this hypothesis, the scientists tracked how hummingbirds behaved in the vicinity of two drinkers. One contained simple sugar syrup and the other contained a mixture of sugar syrup with small amounts of substances produced and secreted by bees, ants, and other insects that are dangerous to hummingbirds.
Observations of three hummingbird species that grew up in the wild and in nurseries showed that these birds reacted differently to odors, that is, they were actually able to distinguish them. In particular, they avoided those drinkers that had syrup with corrosive formic acid and other substances that ants produce. At the same time, they ignored the smell of bees, which attack hummingbirds very rarely, and they also did not respond to various artificial scent additives.
According to Rankin and her colleagues, the results of their study suggest that many hummingbird species use their sense of smell to recognize signs of danger and search for safe food sources. This may indicate that other birds may use this ability much more frequently than is traditionally thought, the ornithologists concluded.