from 1610s in reference to various birds, especially the nightjar, from night + hawk (n.). Figurative sense of "one who stays up and is active at night" is from 1818.
Entries linking to night-hawk
night n.
late Old English niht (West Saxon neaht, Anglian næht, neht) "the dark part of a day; the night as a unit of time; darkness," also "absence of spiritual illumination, moral darkness, ignorance," from Proto-Germanic *nahts (source also of Old Saxon and Old High German naht, Old Frisian and Dutch nacht, German Nacht, Old Norse natt, Gothic nahts).
The Germanic words are from PIE *nekwt- "night" (source also of Greek nyx "a night," Latin nox, Old Irish nochd, Sanskrit naktam "at night," Lithuanian naktis "night," Old Church Slavonic nosti, Russian noch', Welsh henoid "tonight"), according to Watkins, probably from a verbal root *neg- "to be dark, be night." For spelling with -gh- see fight. The vowel indicates that the modern English word derives from oblique cases (genitive nihte, dative niht).
The fact that the Aryans have a common name for night, but not for day (q.v.), is due to the fact that they reckoned by nights. [Weekley]
Thus in Old English combinations night was "the night before (a certain day or feast day);" compare German Weihnachten "Christmas," literally "holy night." In early times, the day was held to begin at sunset, so Old English monanniht "Monday night" was the night before Monday, or what we would call Sunday night; so saeterniht "Friday night." The Greeks, by contrast, counted their days by mornings.
To work nights preserves the Old English genitive of time. Night soil "excrement" (1770) is so called because it was removed (from cesspools, etc.) after dark. Night train is attested from 1838; night-school from 1520s; night-life "habitual nocturnal carousing" is attested from 1852.
hawk n.
c. 1300, hauk, earlier havek (c. 1200), from Old English hafoc (West Saxon), heafuc (Mercian), heafoc, "hawk," from Proto-Germanic *habukaz (source also of Old Norse haukr, Old Saxon habuc, Middle Dutch havik, Old High German habuh, German Habicht "hawk"), from PIE root *kap- "to grasp" (source also of Russian kobec "a kind of falcon"). Transferred sense of "militarist" attested from 1956, probably based on its opposite, dove.
night-owl n.
"owl which flies at night," 1590s; applied since 1846 (American English) to persons who are up or out late at night. Compare night-hawk, also French hirondelle de nuit "prostitute," literally "night-swallow."