Tiercel
Tiercel , noun
[Old English tercel, tercelet, French tiercelet, a dim. of (assumed) tiercel, or Late Latin tertiolus, dim. from Latin tertius the third; -- so called, according to some, because every third bird in the nest is a male, or, according to others, because the male is the third part less than female. Compare Tercel.]
(Falconry) The male of various falcons, esp. of the peregrine; also, the male of the goshawk. — Encyc. Brit
Also: Tiercelet