The dorhawk or nightjar.
nightjar definition by Webster's New World
Webster\'s New World College Dictionary Copyright © 2010 by Wiley Publishing, Inc., Cleveland, Ohio. Used by arrangement with John Wiley & Sons, Inc.
any of a family (Caprimulgidae) of goatsuckers; esp., the common European nightjar (Caprimulgus europaeus)
Origin of nightjarnight + jar: from the whirring noise made by the male
nightjar definition by American Heritage Dictionary
The American Heritage® Dictionary of the English Language, 4th edition Copyright © 2010 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
Any of various chiefly nocturnal, insectivorous birds of the family Caprimulgidae, especially those in the genus Caprimulgus. Also called goatsucker.
Origin of nightjarnight + jar2 (from their harsh calls).