These owls are most frequently seen in flight and in fading light, so the field marks used for perched birds are rarely helpful. The key to the barn owl is the overall pale and uniform color of most birds. Except for the snowy, the barn owl is the palest of the North American owls.
Many, including females and some young birds, appear almost pure white below when they are in flight. Even the birds with buffy breasts and bellies are quite white on the underside of the wings, resulting in an overall pale look.
The orange and pale gray feathers on the back and wings give the bird a paler look than other owls, but more important is the uniform look. The birds may look slightly darker on the back, but the rest of the upperparts are basically unicolored.
Even in winter barn owls will give their characteristic hissing screech as they quarter a field or a marsh. What makes it distinctive is that it is a fairly long call and ends abruptly, as if it were being bitten off—a slightly high-pitched ssssssssssssssssshhpp.