BookDavid Costantini, Muséum National d'Histoire Naturelle, Paris, Giacomo Dell'Omo, Ornis Italia.
Summary: "The family Falconidae constitutes a group of small to medium-sized diurnal raptors whose monophyly is strongly supported. Kestrels are included in the subfamily Falconinae. There are at least 13 species that belong to the kestrel group, but recent genetic studies suggest that the number of kestrel species might be larger, possibly 16. The paleontological and molecular evidences are congruent in suggesting an evolutionary radiation of kestrels from the Late Miocene (5.6 to 9.8 million years ago) through the Early Pleistocene"-- Provided by publisher.