For a human, a breezy garden is a peaceful scene: dandelion seeds float, leaves creak, and flowers sway on their heads.
But if you are a bee, it is a minefield. For a tiny creature with delicate wings, the seeds in the air, the moving leaves, and the moving flowers are basically projectiles, trap doors, and Godzilla-tipped skyscrapers.
It is a situation that honey bees and other pollinators face on a daily basis while collecting nectar and pollen. But while researchers have looked at how bees navigate on windy days or in tight spaces, “no one has really reconstructed how they move through obstacles in the wind,” said Nicholas Burnett, a postdoctoral researcher at the University of California, Davis.
In a study published this month in the Journal of Experimental Biology, Dr. Burnett and his colleagues addressed this gap and found that when things get tough, bees seem to collapse and hope for the best.
For the study, the researchers built a bee obstacle course. They spaced four rods an inch and a half apart on a rocking platform that could move them from side to side, like swaying stalks. They then put the entire setup into a flight tunnel, with a fan at each end.
Honeybee volunteers were recruited from across the campus. The researchers flew them through the course one at a time, in various conditions: in still air, against the headwind and powered by a tailwind, and with stationary or moving obstacles, and filmed their efforts with a camera high-speed video. . The bees were sent home again, unfortunately without rewards.
When they went to the tape, the researchers discovered that the bees’ flight strategy changed depending on the conditions they faced. When faced with moving rods in still air, they flew more slowly than when they encountered stationary obstacles.
“You could interpret that as if they were more cautious, because something unexpected is happening in front of them,” said Dr. Burnett. (In nature, trembling vegetation on a calm day could indicate the presence of a predator or a lawnmower.)
But when the wind picked up, in either direction, honey bees “really sped up the speed with which they fly” by about 50 percent when the rods were moving compared to when they were still still, he said.
When faced with complex airspace, the bees seemed to act “cautious in the still air and brave in the wind,” he said.
The study underscores that animals, including honey bees, are actually complex decision-makers, “they are not one-trick ponies,” said Glenna Clifton, an assistant professor at the University of Portland who studies insect locomotion and not participated in the study. In addition to wind, “there are many other factors that probably play a role” in your flight choices, including light level, time of day, and abundance of food.
As for what explains these different strategies, Dr. Burnett hypothesizes that it could be the same force that makes us run through rain storms: the need to “overcome obstacles as quickly as possible,” he said. This idea was underlined by further analysis, which focused on how successful bees managed to avoid collisions. In still air, slowing down was helpful. But in the wind, speed didn’t matter, and the destruction-free transit was determined by how well the bees scored while flying through the bars.
The fact that the bees are using a “smile and run” strategy is an intriguing hypothesis, Dr. Clifton said, adding that he would like to see more studies focused on whether there was a time when the bees decided to speed up.
It also reminded him of human competitors on obstacle reality shows.
“If you watch those shows, there are interesting times when someone who is cautious and deliberate in a figurative sense raises his arms, hopes for the best and simply does it,” he said. Sometimes that is the most effective strategy.