The Réunion Kestrel (Falco duboisi) is an extinct bird of prey belonging
to the falcon family.
It inhabited the Mascarene island of Réunion and
was part of the Western Indian Ocean radiation of kestrels.
Known from subfossil bones and the writings of Dubois published in 1674
this bird was larger than its relative F. punctatus on Mauritius, being about the size of a Common Kestrel, or around 35 cm from head to tail, with males being noticeably smaller than females.
This trait, while present in most birds of prey, is most pronounced
in the larger, bird-eating species and reduces between-sex competition by niche differentiation. It can be assumed that
the bird was of the same generally brownish coloration as its closest relatives, with a lighter underside and darker spots or stipples, the tail, brown or more probably grey, being banded and tipped black. Its feet were yellow and large relative to the bird's overall size.
The wingspan was 60-70 cm
its wings being more rounded than those of the Common Kestrel - just as in the Mauritius bird - for increased maneuvrability when hunting in the forest. It is probable, but not certain, that the only difference between the sexes was their size.
The bird fed mainly on birds
but certainly also on insects and the local gecko; Dubois noted that despite their
small size they were able to prey on (presumably half-grown) domestic chickens.
