Perching is a highly motivated behaviour in hens with roots in predator avoidance during ancestral evolution. Access to appropriate perches contributes to bone strength and reduces the keel bone fracture epidemic in commercial flocks.
The keel bone fracture epidemic in commercial laying hens is one of the most significant unresolved welfare problems in the egg industry. The keel bone (sternum) is a large prominent bone that is vulnerable to fracture through collision with housing structures, other hens, and falls from elevated surfaces. Once fractured, the bone heals but often misaligns, causing ongoing pain that is detectable through pain sensitivity testing and palpation. The welfare impact of chronic keel fractures is compounded by the fact that hens continue to attempt normal behaviour including perching, often re-injuring already compromised bone. Access to appropriate perches during the rearing phase significantly improves bone mineralisation and muscle coordination, reducing collision and fall frequency. Breed selection also influences keel fracture risk - lighter breeds with better flying ability generally have lower rates.