[2][3] The sickle-winged nightjar was described as Amblypterus anomalus which was later lumped into genus Caprimulgus.

Since the early 2010s it has been placed in its current genus Eleothreptus, which it shares with the white-winged nightjar (E. candicans).

The wings have a hooked "sickle" appearance due to the shape of the primary flight feathers.

It is believed to be resident in most or all of its range but there are suggestions that it migrates north from Argentina following the breeding season.

Between sallies it sits on roads and trails or perches on low branches or wire fence.

Its fairly small population is rapidly declining due to habitat loss and degradation.