a nighthawk is a nocturnal bird of the subfamily chordeilinae , within the nightjar family , caprimulgidae .
the term "nighthawk", first recorded in the king james version of 1611, was originally a local name in england for the european nightjar .
its use in the americas refers to members of the genus chordeiles and related genera was first recorded in 1778.nighthawks are medium-sized birds with long wings , short legs , and very short bills .
they usually nest on the ground .
they feed on flying insects .
the least nighthawk , at 16 centimetres (6.3 in) and 23 grams (0.81 oz), is the smallest of all caprimulgiformes .
nightjars are sometimes referred to as goatsuckers from the mistaken belief that they suck milk from goats (the latin for goatsucker is caprimulgus) .
nighthawks have small feet , of little use for walking , and long pointed wings .
their soft plumage is cryptically coloured to resemble bark or leaves .
some species perch facing along a branch , rather than across it as birds usually do .
this helps to conceal them during the day .
the female lays two patterned eggs directly onto bare ground .
they are mostly active in the late evening and early morning or at night and feed on moths and other large flying insects .
the bill opens very wide and has a slightly hooked upper tip .
nighthawks are similar in most respects to the nightjars , but have shorter bills and plumage that is less soft .
nighthawks are less strictly nocturnal than many nightjars and may be seen hunting when there is still light in the sky .
