A wake at night: Aviation engineering has always been driven by a desire to emulate by the world’s natural fliers. Even the word aviation derives from the latin name for a bird, avis. Supported by research programs into multifunctional materials at AFRL/AFOSR, we are now returning to observations of biology to take crewed and uncrewed aircraft to the next level through a deeper understanding of their architecture, aerodynamics and control systems. Bird wings and tails comprise multifunctional materials to deliver robust, reconfigurable, warping airframes that adapt to mission-specific performance profiles and often dramatic levels of atmospheric turbulence. Gliding birds of prey offer a fabulous opportunity to study these capabilities. During the study that produced this striking image of a Tawny Owl called Hector, we flew a range of raptors through clouds of neutrally-buoyant, helium-filled, soap bubbles, automatically tracking 20,000 of them to quantify the flow fields. This long-exposure photograph reveals downwash in the near wake and trailing vortices behind the slotted wing tips. We discovered that these birds adopt a tail posture that minimizes aerodynamic drag by generating more lift than would be expected if following conventional aircraft design theory. Their enhanced efficiency comes at the cost of passive longitudinal stability. Fortunately, the birds also demonstrate what can be done with rapid sensing, processing and actuation – not only when gliding, but also when hunting prey. Contributors: James R Usherwood, Jorn A Cheney and Richard J Bomphrey