How much do birds coast?

Answer 1

It depends on the type of bird and a characteristic called "wing loading," a ratio between weight and wing area. Small, heavy birds such as a grouse have high wing loading and therefore flap their wings quickly to achieve flight. Hummingbirds, despite their small size, must flap at incredible speeds of many dozens of times a second in order to hover and maneuver the way they do. Birds with a relatively large wingspan relative to their weight, such as the magnificent frigatebird (the bird with the largest wing area to weight ratio) can fly long distances with minimal flapping.

Small birds such as finches have a unique flight pattern called "undulating" where they flap their wings a few times to achieve an upward angle of flight, then coast in a parabolic arc until they are pointed downward, then flap again and so on. Other birds have a method of flight called "direct" that means they beat their wings constantly and fly straight. Others, such as vultures and buteo hawks, soar in circles to ride rising air currents and then coast for long distances; this behavior saves energy.