"Hummingbirds have a unique collision avoidance system built into their brains that allows them to perform high-speed aerobatics in safety. The super-agile birds, whose wings beat up to 70 times a second, can hover, fly backwards, and whizz through dense vegetation at more than 50 kilometres per hour. How they manage to avoid potentially fatal crashes has remained a mystery until now. Researchers in Canada conducted a series of experiments which showed that the birds process visual information differently from other animals. As they dart and dive at speed, they judge distance from the way looming objects appear to get bigger, and vice versa."