The term "goatsucker" often elicits snickers and snide comments from those unfamiliar with it, but it simply refers to birds in the Caprimulgidae family, including Common Nighthawks. I studied urban nighthawks' nest-sites while in graduate school at the University of Northern Iowa (and I will publish that study one of these years!).
The birds apparently were given that name based on their buccal anatomy - they have large mouths with very little bill (beak) - great for scooping up insects while in flight.
Aristotle may have coined the term "goatsucker" in 350 B.C.E.:
"The socalled goatsucker lives on mountains; it is a little larger than the owsel, and less than the cuckoo; it lays two eggs, or three at the most, and is of a sluggish
disposition. It flies up to the shegoat and sucks its milk, from which habit it derives its name; it is said that, after it has sucked the teat of the animal, the teat dries up
and the animal goes blind. It is dimsighted in the daytime, but sees well enough by night."
(Aristotle, & Thompson, D. (n.d). History of Animals. Generic NL Freebook Publisher.)