#  Flight Through Narrow Spaces 

 



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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)



 

   ![williamspnas2015_wingfoldvswingpause.jpg](/sites/g/files/omnuum6301/files/styles/hwp_1_1__720x720_scale/public/biewener/files/williamspnas2015_wingfoldvswingpause.jpg?itok=S_U0QSUH)