Too often it is mistaken for the whippoorwill. The night hawk does not have the weird and woful cry of that more dismal bird, but gives instead a harsh, whistling note while on the wing, followed by a vibrating, booming, whirring sound that Nuttall likens to "the rapid turning of a spinning wheel, or a strong blowing into the bung-hole of an empty hogshead." This peculiar sound is responsible for the name nightjar, frequently given to this curious bird. It is said to be made as the bird drops suddenly through the air, creating a sort of stringed instrument of its outstretched wings and tail. When these wings are spread, their large white spots running through the feathers to the under side should be noted to further distinguish the nighthawk from the whippoorwill, which has none, but which it otherwise closely resembles. This booming sound, coming from such a height that the bird itself is often unseen, was said by the Indians to be made by the shad spirits to warn the scholes of shad about to ascend the rivers to spawn in the spring, of their impending fate.