Question:
I know that Hummingbirds can do some pretty amazing things, but is it true that they also have the ability to smell?
Response:
We have always known that Hummingbirds use visual cues to locate flowers and collect their nectar. And they can even use their amazing spatial memories to remember what flowers they have visited. But who would have thought that they also use smell? Ashley Kim and her co-investigators at the University of California at Riverside decided to put this to the test by offering over 100 Hummingbirds a choice between two feeders, one with just sugar water and another with added scents indicating the presence of certain insects. You see, bees, wasps and ants not only drain the nectar in flowers they visit, they can also repel Hummingbirds from flowers they occupy. Wasps physically chase them off, whereas ants deposit irritating formic acid. Because these creatures sometimes deposit chemical cues during foraging and agonistic interactions, the researchers wanted to find out if bees use smell as part of their procedure to avoid wasting time on flowers already visited by other nectar-seekers or worse, being physically repelled by competitors. The results were interesting. Kim and her team found that their Hummingbirds did indeed avoid flowers with the scent of two kinds of ants, but not less harmful honeybees. But would that mean that Hummingbirds would also avoid sugar water feeders if wasps and/or ants had left chemical cues on them? While the scientists did not test that hypothesis, I am guessing that the hummers will not avoid them for several reasons. First, I am not sure that wasps and ants can leave chemical cues on a smooth plastic feeders. Second, unlike flowers, feeders are only limited in the nectar they supply by how often we fill them. Third, I do not believe that Hummingbirds use the same foraging strategies with our feeders. If the wasps and ants are not present on a given feeder, that should mean open season for any Hummingbird.
David M. Bird, Ph.D., Emeritus Professor of Wildlife Biology, McGill University www.askprofessorbird.com
David M. Bird is Emeritus Professor of Wildlife Biology and the former Director of the Avian Science and Conservation Centre at McGill University. As a past-president of the Society of Canadian Ornithologists, a former board member with Birds Canada, a Fellow of both the American Ornithological Society and the International Ornithological Union, he has received several awards for his conservation and public education efforts. Dr. Bird is a regular columnist on birds for Bird Watcher’s Digest and Canadian Wildlife magazines and is the author of several books and over 200 peer-reviewed scientific publications. He is the consultant editor for multiple editions of DK Canada’s Birds of Canada, Birds of Eastern Canada, Birds of Western Canada, and Pocket Birds of Canada. To know more about him, visit www.askprofessorbird.com or email david.bird@mcgill.ca.
