Great time to bring up my fun fuck fact. "Windfucker" was an archaic name for the 
common kestrel. Its etymology is debated, though.
The most commonly proposed theory is that it preserves an archaic usage of the word "fuck," (see: 
Wiktionary, 
Etymonline) which is thought to have meant "strike" or "beat" at one point in time. So the Kestrel was sort of like a "fist" flying through the sky, punching it! This would also make the word "fuck" related to the words punch and fist, as well as "pinchar" in Spanish. This is rather contentious though, as some scholars think that "fuck" really doesn't have cognates outside of the Germanic languages, and their forms/meanings are pure coincidences.
The more boring theory, imo, is that "windfucker" actually comes from the word "windsucker." From what we know, these words have attested usages 
very close in time. So it is likely that the usage of one begot another. Now, why would this shift happen? Well, "windfucker" to "windsucker" is referred to as 
bowdlerisation, named after 
Thomas Bowdler, the author who published a family-friendly edition of William Shakespeare's plays called 
The Family Shakespeare. However, "windsucker" to "windfucker" is more interesting, because it could have to do with similarities in the writings of both characters. See, while I write it "windsucker," Middle English scribes used a character known as a 
long-s ( ſ ), which looked very similar to an f but without the bar running through it. Therefore, some scribes may have mixed up the "s" and "f" characters and began to refer to it by a funny name.