Where is WAIR (and other wing-assisted behaviours)? Essentially everywhere: a response to Kuznetsov and Panyutina (2022)

Kuznetsov and Panyutina (2022) offer a reanalysis of the kinematic and force plate data previously published by Bundle and Dial (2003). Their intention is to describe instantaneous wing forces during wing-assisted incline running (WAIR), focusing particularly on the upstroke phase. Based on their interpretation of wing forces and muscle function, the authors conclude that 'WAIR is a very specialized mode of locomotion that is employed by a few specialized birds as an adaptation to a very specific environment and involving highly developed flying features of the locomotor apparatus', and thus not relevant to the evolution of avian flight. Herein, we respond to the authors' interpretations, offering an alternative perspective on WAIR and, more generally, on studies exploring the evolution of avian flight.