How barn owls balance instability for efficient flight

Small drones are impressively fast, but they still can’t maneuver as well as similar-sized birds of prey in the air. One reason is that stability is affected by morphological geometry. Drones are typically stable in the longitudinal direction: They can naturally return to their original flight path after small disruptions. However, some birds are not stable, allowing them to change direction quickly. Ye et al. studied the gliding barn owls to understand how to improve flight performance in drones.

The authors found that gliding owl models can stabilize themselves in the air by changing their tail angle to compensate for their virtually moving center of gravity. Interestingly, the owls studied glided most efficiently when they were moderately unstable and pitched their tail slightly down. This indicates that this bird of prey can achieve both high efficiency and high maneuverability at the same time — a phenomenon that also reveals the evolutionary pressure on birds of prey.

“The ultimate goal is to build a unified theoretical framework connecting body geometry, static stability, wing-tail coordination and aerodynamic efficiency,” author Jialei Song said.

For their study, the authors created high-fidelity 3D models from high-speed camera images of real barn owls taken while they were gliding. Next, the authors ran 75 advanced simulations on owls flying at different tail postures and angles of attack to determine the aerodynamic forces. Using these results, the team then built a theoretical model that explains how the owl’s center of gravity, tail position, and flight efficiency are connected.

To expand their framework, the team plans to test other bird species and the effects of wing movements on flight performance.

Source: “Instability and tail pitching-down benefit the aerodynamic efficiency of barn owl in equilibrium gliding,” by Zisheng Ye, Haotian Gu, Viet Dung Duong, Hongmin Wang, Ling Yin, and Jialei Song, Physics of Fluids (2026). The article can be accessed at https://doi.org/10.1063/5.0342734 .