Flight Through Narrow Spaces

Based on the impressive maneuvering performance observed from our artificial forest cluttered flight trials, work by post-doc C. David Williams has asked how pigeons traverse narrow vertical spaces. This work shows that pigeons adopt one of two strategies, wing pause or wing-fold, to negotiate narrow spaces. Interestingly, pigeons shift toward a wing-fold strategy as spacing becomes more narrow. Using a mass-distribution model of the pigeon (Ros et al. PNAS 2011), we found that wing-folding reduces collisional rotational instabilities of the bird by about 18-29%. Wing-pausing used for wider spacing, on the other hand, may enable pigeons to cope with subsequent maneuvering requirements as the wings can more rapidly produce downstroke aerodynamic forces. (Williams & Biewener, PNAS 2015)

Wing Pause Strategy (increased preference for wider openings)

Wing Fold Strategy (increased preference for narrow openings)