Image of the Day: Flight Styles

The evolution of different ways of flying in birds affected wing range of motion, but not wing shape.

Oct 25, 2019
Emily Makowski
Clockwise from top left: gyrfalcon (Falco rusticolis), American kestrel (Falco sparverius), belted kingfisher (Megaceryle alcyon), red-crested turaco (Tauraco erythrolophus), bar-headed goose (Anser indicus), and red-tailed hawk (Buteo jamaicensis). Wings are from the Cowan Tetrapod Collection at the Beaty Biodiversity Museum in Vancouver, British Columbia, Canada.
Vikram B. Baliga

Different ways of flying, such as soaring, gliding, and flapping, have evolved in birds over time. The evolution of these diverse flight styles has changed the range of motion of different species’ wings, but not their wing shape, suggests a study published in Science Advances Wednesday (October 23). Doug Altshuler, comparative physiologist at the University of British Columbia, and colleagues determined the range of motion of wings from 124 bird cadavers representing 61 species. They also observed live birds in flight. The researchers then developed a model to determine how bird flight behavior and body mass could explain variations in wing shape or range of motion in the wings. 

Birds that use flapping, bounding (short bursts of flapping alternated with wings folded against the body), or gliding tended to have a lower body mass and greater range of motion in the wings compared with birds that use air currents to soar. They had a higher body mass and more limited range of motion. However, different wing shapes only loosely correlated with flight behaviors and body mass. The results suggest that the plethora of wing shapes that has evolved in birds has little to do with the way they fly. Instead, changes in a species’ flight style affects how their range of motion changes.  

Composite image of a glaucous-winged gull (Larus glaucescens) gliding through the air
Vikram B. Baliga

V.B. Baliga et al., “Range of motion in the avian wing is strongly associated with flight behavior and body mass,” Sci Adv, doi:10.1126/sciadv.aaw6670, 2019.

Emily Makowski is an intern at The Scientist. Email her at emakowski@the-scientist.com