if it has any white in its wing spectrum, it has some mallard in the wood pile(also, if you have a true balck to compare, the spectrum will be more purple than blue).the question is, to what extent or to what percentage.im assuming your asking for hunting reg purposes? areas that have alot of crosses will be easier to "claim" them as mallard in a limit as the wardens are likely to know or have more education on them.around here, the damn thing better have a solid green head or your sol as most of the wardens know very little about waterfowl.myself and a buddy have spent the last two seasons trying to teach the local biologist while being checked at the ramp, the difference between drake and hen bluewing teal.we finally gave up when trying to show him juvenile vs adult birds.he was marking his little harvest sheet to send somewhere and was just splitting them half and half based on the numbers we killed.this is a biologist, not a warden which you would think would have a clue.
