Found this one on a French site; I'll have to get my son to translate for me. Made a few mods due to materials at hand - grizzly instead of CDL for the tail (don't got none) and hen pheasant breast for mallard (2700 miles away; also like the markings on the pheasant). Cool fly; change colors to suit your needs.
hook - Dai Riki 320 #14
thread - MFC 8/0 sand
tail - grizzly
abdomen - goose biot yellow
hackle - dun
collar - hen pheasant breast
Part 1
mash barb, start thread, wrap to point above barb and create a small bump
even tips on a clump of hackle barbs; measure (shank length) and tie in
tie in (moistened) biot, notch side down; wrap to 50% mark, tie off/trim
tie in hackle; wrap forward (leave one hook eye width behind eye)