Size doesn’t matter – power and shape do
Muscle capacity and wing shape determine how well hummingbirds can maneuver in flight.
The ability of an animal to maneuver can determine its success at avoiding predators, catching prey, and outperforming its competitors. However, little is known about the characteristics that determine maneuverability. Why are some individuals more maneuverable than others?
To investigate this question, Paolo Segre and co-workers used an automated video tracking system to track male Anna’s hummingbirds as they flew around a large chamber. These tracks were then compared with the physical characteristics of the birds to see which, if any, affect the birds’ maneuverability. This revealed that body size did not affect how well the birds could maneuver. Instead, the muscle capacity of the birds — their ability to generate force rapidly — determined how well the birds performed most types of movement. Birds with higher muscle capacity flew faster, had faster accelerations and decelerations, could rotate their bodies more quickly, and performed more demanding and complex turns.
Segre and colleagues also found that wing shape is important for a type of maneuver called an arcing turn. Hummingbirds with a more slender wing shape were able to execute more demanding arcing turns involving higher accelerations, and they used arcing turns more often than birds with wider wings. Future research will aim to determine whether these relationships are also found in other species of birds.
To find out more
Doug Altshuler talks about the importance of burst muscle capacity in episode 27 of the eLife podcast.
Read the eLife research paper on which this eLife digest is based: “Burst muscle performance predicts the speed, acceleration, and turning performance of Anna’s hummingbirds” (November 19, 2015).
