Hydration‐Induced Shape and Strength Recovery of the Feather

As necessary appendages to the bird wing for flight, feathers have evolved to address the requirements of aerial locomotion. One of the recently discovered, fascinating aspects of this is their ability to recover shape and strength with hydration. This feature significantly enhances the effectiveness of a bird's flying capability as it allows for the natural restoration of feathers damaged by predators or other external forces. Herein, this capability is analyzed and it is demonstrated that the feather shaft can regain approximately 80% of its strength in the calamus, and 70% in the rachis when subject to a hydration step after being bent to failure. The matrix of the nano‐composite structure within the feather shaft is thought to swell and soften when hydrated, reorienting the stiffer buckled fibers back to their original position. Upon drying, the strength is recovered. Experimental results are found to support this hypothesis, and a finite element calculation of hydration‐induced recovery demonstrates the effect. Smart, self‐healing composites based on approaches learned from the feather have the potential to allow for the creation of a new class of resilient materials. Feathers are found to recover their shape and strength with hydration, a feature which significantly enhances the flying capability of birds by allowing for the natural restoration of damaged feathers. The matrix of the nanocomposite structure within the feather shaft is thought to swell and soften when hydrated, reorienting the stiffer buckled fibers back to their original position.