kestrel.

From Middle English castrel (“staniel, bird of prey”), from Middle French cresserelle, crecerelle (“bird of prey”), usually assumed to be from crecelle (“rattle, wooden reel”) (modern crécelle), of obscure origin. Cognates possibly include: Medieval Latin clisterella f, French crécerelle f and cristel m, Neapolitan castariello m and crestariello m, all sharing the same meaning. Derivation from the assumed Vulgar Latin *crepicella, *crepitacillum, a diminutive of crepitāculum, from crepitāre (“to crackle”) is difficult to explain from a morphological point of view. Instead, possibly from a root *krek-, *krak- (“to crack, rattle, creak, emit a bird cry”), from Middle Dutch crāken (“to creak, crack”), from Old Dutch *krakōn (“to crack, creak, emit a cry”), from Proto-West Germanic *krakōn (“to emit a cry, shout”), from Proto-Indo-European *gerg- (“to shout”). Cognate with Old High German krahhōn (“to make a sound, crash”), Old English cracian (“to resound”), French craquer (“to emit a repeated cry, used of birds”). More at creak, crack.