The letter-winged kite (Elanus scriptus) is a nocturnal member of an otherwise diurnal genus.
It is the only nocturnal kite. I studied this bird during the early 90's when favourable rains led to plague proportions of its major prey species (the Long-haired rat, Rattus villosissimus) on the Mitchell grass plains of the upper reaches of the Georgina and Diamantina rivers in far Western Queensland.

I have written a book on this bird, extracts of which I have linked. The major findings are:-
 

•    The nocturnal adaptation is very recent and limited.
•    Efficient hunting by this species requires moonlight
•    The retina has two strikingly visible foveas, unlike any other nocturnal raptor, but just like its diurnal sister taxa
•    Courting, nesting and incubation are synchronised to the moon
•    Hatching occurs at full moon
•   The major visual change appears to have been an increase in eye size and total numbers of retinal ganglion cells