Evolutionary shifts from diurnal to nocturnal niches are often associated with visual system change. Under low-light conditions, retinal sensitivity increases, triggering corresponding changes in the optic nerve and retinorecipient brain regions. In birds, these changes are not only evident in the soft tissues of the nervous system, but also skull morphology. Thus, skull measurements can be used as a proxy for some aspects of sensory system evolution in nocturnal species. Here, we use this approach to infer the visual abilities of the letter-winged kite (LWK; Elanus scriptus). This species is the only nocturnal hawk and is thought to possess several owl-like anatomical traits. Using μCT scans, we reconstructed endocasts of LWKs and 14 diurnal hawk and falcon species and acquired measurements of the visual system from the endocasts and skulls. In contrast to many other nocturnal birds, the LWK did not differ from diurnal species in the relative size of its orbits, optic foramina or optic lobes. We also did not detect any differences in orbit orientation between the LWK and other species, including its congener (Elanus axillaris). Nocturnal foraging in LWKs might therefore be facilitated by more subtle anatomical changes, such as rod:cone ratio, than what is observed in many other nocturnal bird species. However, without accompanying changes in osteology that we could detect, the LWK is unlikely to have the visual sensitivity typical of other nocturnal avian predators, such as owls. We conclude that not all nocturnal birds evolved large changes in skull morphology and therefore inferring activity patterns of extinct species may not be possible from osteology alone.