Sandhill Crane and Optical Illusion

Stopped at Willowbrook Wildlife Center in Glen Ellyn, Illinois after running an errand in Lombard.  WWC rehabilitates/cares for wild animals injured in DuPage County, and in the "back 40" acreage east of the facility a pair of sandhill cranes reside inside a fenced enclosure. When I was two meters from the fence both cranes raised their bills in the air and let out a loud rattle call, which startled me.

The photo is the male crane, and was taken through the wire fence with the lens aperture wide open (f5.6 in this case) to minimize seeing the fence. The illusion? The hexagonal fence wire appears to be on the far side of the crane, but in reality is between the camera and the bird's head. Look on the bird's neck just above the bottom of the photo frame, and a dark band from the wire is noticeable.  The band is not a shadow, as this fence was on the west side of the enclosure and it was not even noon yet.

Extra photo: one of three red-tailed hawks in the back 40. Shutter speed of 1/2500 was adequate this time, and low ISO 320 to boot!