What is the fastest bird when diving?

A peregrine falcon in a stoop exceeds 380 kilometres an hour, which makes it the fastest animal of any kind. It is not flying so much as falling on purpose - wings tucked, body shaped into a teardrop, aiming to strike prey in mid-air with a closed foot hard enough to kill on impact.

Going that fast through air creates a problem breathing: the pressure would damage the lungs of most animals. The peregrine has bony tubercles in its nostrils that break up the airflow, an arrangement often said to have inspired the design of jet engine inlet cones. It also has a third eyelid that sweeps across the eye continuously to clear it without blinking.

The species nearly disappeared in the twentieth century and its recovery is one of the better conservation stories. DDT accumulated up the food chain and interfered with calcium metabolism, so peregrine eggshells became too thin to survive incubation; the population collapsed across Europe and North America, and was extinct east of the Mississippi. Banning DDT and releasing captive-bred birds brought them back so successfully that peregrines now nest on cathedrals and office towers, hunting the pigeons of city centres from ledges that work exactly like cliffs.