Apochrypha
22.02.2021 Filed in: science, swifts
One of the persistent factoids told about swifts is their alleged ability to flap their wings independently. However, as long ago as 1950 this was pretty much debunked as an illusion by D B O Savile in their paper "The Flight Mechanisms of Swifts and Hummingbirds" in the 4th issue of the 67th volume of The Auk journal. It is an interesting read for a number of reasons. For the sake of this discussion, we can assume that the wing structure and flight patterns attributed to the chimney swift will apply to the common swift apus apus.
https://academic.oup.com/auk/article/67/4/499/5223257?login=true