Hummingbirds can pick up a variety of odors that tell birds about danger or where to get food.
It turned out that hummingbirds can not only catch the smells of flowers, but also potentially dangerous places that are best avoided.
Previously, scientists did not know that hummingbirds can pick up odors, since the flowers they pollinate usually do not smell strongly. In addition, these birds are very small and it was difficult to find olfactory bulbs in them.
Scientists in a new work showed for the first time how hummingbirds, based on smells, make decisions about where to look for food and where not to fly. To understand this, the researchers observed 100 hummingbirds choosing between two feeders: one containing sugar water and the other containing sugar water mixed with one of several chemicals whose scent signals the insect’s presence. There were no visual differences between the feeders.
For the second feeder, the researchers used formic acid, a protective compound produced by ants, and a substance from European bees.
Hummingbirds avoided both ant chemicals, especially formic acid. However, they did not react in any way to the smell of the honeybee, which discourages other bees from visiting the flowers.
To make sure that the birds were reacting to the chemical itself, and not just afraid of new odors, the researchers conducted an additional test with ethyl butyrate, a common food additive that birds could not encounter anywhere. But the additive did not affect their decision in any way.