Environment

Scientists find how hummingbirds avoid high-speed collisions

Researchers have discovered hummingbirds process visual information differently from other animals. This difference helps them in their extreme aerial acrobatics. They can travel faster than 50 kilometres per hour and stop on a dime while flying through dense vegetation. “Birds fly faster than insects and it’s more dangerous if they collide with things,” said Roslyn Dakin, a postdoctoral fellow in the UBC’s department of zoology who led the study. In order to figure out how hummingbirds avoid collision, scientists at UBC placed the birds in a specially designed tunnel while projecting patterns on the walls. Observations were then made to see how the birds navigate to avoid collisions. “We took advantage of hummingbirds’ attraction to sugar water to set up a perch on one side of the tunnel and a feeder on the other, and they flew back and forth all day,” said Douglas Altshuler, associate professor in the department of zoology. “This allowed us to test many different visual stimuli.” When scientists simulated this information on the tunnel walls, the hummingbirds showed no reaction. On the other hand, Dakin and her colleagues found the hummingbirds depended on the size of an object to determine their distance. As something grew bigger, it was a signal that the object is getting closer and vice-versa. This is in contrary to the humans and the bees where speed of an object indicates its distance as the object goes passed their field of vision. “When objects grow in size, it can indicate how much time there is until they collide even without knowing the actual size of the object,” said Dakin. “Perhaps this strategy allows birds to more precisely avoid collisions over the very wide range of flight speeds they use.”