Where I hunted up north we always used the dollar bill trick to tell the sex of a woodcock. Males have a beak shorter than the width of a dollar bill and females have a beak longer. Fastest way to tell a woodcock from snipe (besides the size difference) is the direction of the lines on top of their head. Snipe have lines running front to back, woodcock have lines running side to side.

Snipe


Woodcock