By Mindy Weisberger, Senior Writer | February 7, 2018 06:14am ET
Some say that eyes are the windows to the soul. But in owls, the ears are literally windows to the animals' eyeballs.
Unnerving glimpses of the inside of an owl's head — in which a view of the bird's sizable bluish-white eyeball is visible through its ear hole — were captured in photos by writer and naturalist James McCormac, author of "Birds of Ohio" (Lone Pine Publishing, 2004), who shared the images with Live Science.
Like all birds, owls lack the external ear structures found in most mammals; the birds' ears are unadorned openings in their skulls, visible only when the feathers on the sides of the animals' heads are parted. But these owls' unusually large earholes and eyes also offer a "behind the scenes" peek at their visual system, showcasing the evolutionary adaptations in sight and hearing that make the birds so successful at stealthy nighttime hunting, McCormac told Live Science. [Whooo Knew? 10 Superb Facts About Owls]
McCormac photographed his owl subjects — northern saw-whet owls (Aegolius acadicus) — in southern Ohio during a data-collection initiative by Project Owlnet. In this effort, scientists and members of the public track this owl species to understand the bird's migration patterns.
Twice a year — in the fall and spring — participants in the project use audio recordings that mimic the owls' calls to lure the animals into nets, and then the researchers attach bands to the owls' legs, according to the Project Owlnet website. Before the birds were released, McCormac had the opportunity to take a closer look at their heads — and to snap photos of the gaping holes showing the bulging sacks of the animals' eyeballs, he told Live Science.