Ophthalmology of Accipitrimorphae, Strigidae, and Falconidae: Hawks, Eagles, Vultures, Owls, Falcons, and Relatives

Abstract

Birds of prey, also collectively known as raptors, consist of the Falconiformes (falcons and caracaras), Accipitriformes (eagles, buzzards, hawks, kites, and Old World vultures), Cathartiformes (New World vultures), Cariamiformes (seriemas), and Strigiformes (true owls Strigidae, and barn owls Tytonidae) (del Hoyo et al. 1999; Jarvis et al. 2014; McClure et al. 2019). Although grouped together as key apex predators, raptors are phylogenetically heterogenous assimilation with many morphological and ecological differences. Perhaps a most obvious example is revealed in their activity patterns, where most raptors are considered diurnal, except the owls, which are considered nocturnal, a habit they share with two other avian orders for which we have genome sequences (Caprimulgiformes and Apterygiformes) (Martin 1990; Mikkola 1983; Martin 2017; Zhan et al. 2013). However, the ferruginous pygmy owl Glaucidium brasilianum maintains some activity during the day and the snowy owl Bubo scandiacus hunts during the daytime, the American barn owl Tyto furcate is most active in twilight, the burrowing owl Athene cunicularia is cathemeral, and the stripped owl Asio clamator is crepuscular and nocturnal (del Hoyo et al. 1999; Martins and Egler 1990; Motta-Junior 2006; Motta-Junior et al. 2004; Sarasola and Santillan 2014; Martin 1986). Overall, as a group, owls actually exhibit a broad range of activity patterns and habitats (Bowmaker and Martin 1978; Braga 2006). Additionally, nearly one-third of falconiform species, as well as some accipitriformes species, maintain activity during the crepuscular period (Mitkus et al. 2018).