This Great Grey Owl shows its generous wingspan as it takes off.
Canon 5D Mark III with the 500L f4 lens handhaeld @ 1/1000, f4, ISO 1250, +2 1/3 exposure compensation. Slight crop for composition purposes.
According to Wayne Lynch's Owls of the United States and Canada, the Great Grey has the largest wing surface area, around 437-508 sqaure inches for both wings. The Snowy Owl comes second. To compare, the surface area of a sheet of letter paper has around 93 square inches.
Cheers,
Mike