According to a new study, flexible soaring style keeps the vultures aloft longer.
Vultures are poor flappers and need to soar in order to fly, relying on updrafts to gain altitude. They wobble at low altitudes as well as circle high in the air.
The West Virginia University research shows how vultures use small-scale turbulence to stay aloft even when weather conditions don’t favor the formation of thermals.
Researcher Julie Mallon and her colleagues observed vulture behavior at thirteen sites in southeastern Virginia in 2013 and 2014. They found that both Turkey Vultures and Black Vultures used contorted soaring primarily when the weather was cool and cloudy, conditions not optimal for the development of thermals, and when flying less than fifty meters above the ground.
The researchers believe that the vultures were making use of small-scale turbulence that forms when horizontal air currents hit the edge of a forest or a similar barrier, producing a small area of uplift at the tree line.
Using this sort of small-scale turbulence in addition to other sources of updrafts appears to increase the amount of time vultures can spend on the wing, searching for food. Turkey Vultures may especially benefit from low-altitude contorted soaring, they use their sense of smell to find carrion in forests, and by flying along the edge of the trees they have a better chance of finding food while avoiding the notice of higher-flying Black Vultures that might otherwise compete with them for carcasses.
Mallon said that soaring flight is more complex than previously thought and merits more study.
The study appears in The Auk: Ornithological Advances.