Wing assisted incline running

Wing Assisted Incline Running (WAIR) is a hypothesis for the evolution of flight in birds, proposed by Ken Dial in 2003. the idea is that flapping the forelimb/wing increases traction between the feet and the ground and therefore allows birds to climb a steeper slope than without forelimb movement. this theory is backed up by the fact that it solves the previous hypothesis' problems in that it gives reason for the utility of 'half a wing', it makes sense in terms of ecological use for predator escape and also the observation that extant primative birds tend to run rather than fly

with thanks to: Hutchinson J., 2008. The Evolution of Birds, Lecture notes. RVC UK.