I have to say that I do not think this is a Savanna Nightjar. Savanna Nightjar has squarer-looking wings, with a bulge on the trailing edge. Even a female should show a buff patch across the primaries, and the wings would be more heavily barred, and held in a distinct "V" shape.
I think this is a Kestrel. No dark tip to tail is visible, but this bird is slender and finely barred, gliding on flat wings. The head looks odd but maybe it was twisted in a strange position. (Do you have any more photos of this individual ?)
But with a shot like this, perhaps five different commenters will have five different opinions !
John
