Serious birders have keen eyes, but it's likely that not many have enjoyed a detailed glimpse of geese flying with their bodies turned upside down. The accompanying video captures this peculiar event, referred to as whiffling, in slow-motion.
(Watch the goose at the top, and in the middle of the screen at the 15-second mark.) Though the birds twist their bodies upside down, their heads remain upright.
According to New Science, geese perform this maneuver as a means of braking. Paul Stancliffe of the British Trust for Ornithology explains that the maneuver helps the large birds quickly lose height as they approach landing areas.
Stancliffe also said this event is very difficult to detect in real-time.
The video, believed to provide the first slow-motion footage of this phenomenon, was shot by Hans de Koning and Lodewijk van Eekhout, and earned them first prize in a competition organized by the Flight Artists group at Wageningen University and Research Center in the Netherlands.