The meaning of the name Kestrel is “Rattle”. Kestrel is the name of certain breeds of Falcon (also a cool name BTW) it derives from the French word crecelle which means ‘rattle’ and was given this name to reflect the sound of it’s cry.
Kestrel has some very chic nicknames, Kes or Kessie, even Trell has a nice trill to it. I even think Crecelle is a nice variant option on a girl.
This name reminds me of others such as Wren, Sparrow, Dove, Raven, Skylark (or just Lark), Starling, Robin and Finch – clearly because of their bird related heritages. Others with a similar sounds include Cressida (or Cress), Corsica, Ochre, Kelera, Okra, Cosima and Charisma.