kestrel (n.)youdaoicibaDictYouDict[kestrel 词源字典]
kind of falcon, c. 1600, earlier castrell (15c.), probably from Middle French cresserelle, which apparently is related to crecerelle "rattle," from Latin crepitacillium "small rattle," diminutive of crepitaculum "noisy bell, rattle," from crepitare "to crackle, rattle;" possibly from the old belief that their noise frightened away other hawks.[kestrel etymology, kestrel origin, 英语词源]