Chordeiles minor

from The Collaborative International Dictionary of English v.0.48

nighthawk \nighthawk\ n.
   1. A person who likes to be active late at night; a {night
      owl}.

   Syn: night owl, nightbird.
        [WordNet 1.5]

   2. (Zool.) Any of several mainly nocturnal North American
      goatsuckers, especially {Chordeiles minor}, or the related
      European goatsucker {Caprimulgus europaeus}, also called
      the nightjar.

   Syn: bullbat, mosquito hawk.
        [WordNet 1.5]

from The Collaborative International Dictionary of English v.0.48

Caprimulgidae \Caprimulgidae\ n. [L. capris goat + mulgere to
   milk.]
   a widely distributed natural family of nocturnally active
   birds including the {whip-poor-will} ({Caprimulgus
   vociferus}), the {chuck-will's-widow} ({Caprimulgus
   carolinensis}), and the {common nighthawk} ({Chordeiles
   minor}); -- called popularly the {goatsuckers} or
   {nightjars}. The nighthawks are sometimes active during the
   day.

   Syn: goatsuckers, nightjars, family {Caprimulgidae}.
        [PJC]

              The family . . . is alternately known as the
              nightjars (derived from the "churring" sounds of
              several species -- "jarring" the night air), or
              goatsuckers, a nonsense name that should be
              discontinued as it has its origin in the
              preposterous myth that the birds sucked the milk
              of nanny goats until they were dry. --Terence
                                                  Michael Short
                                                  (Wild Birds of
                                                  the Americas)