X2, good post. The pelvic bone "method" is pretty good, at least once the hens are laying age. And the wattles "method" has proved fairly reliable for me. Not by size, but by direction, the hens wattles tend to cup inward like hugging their face and the males wattles will cup out. has worked for me, but from what I read it's not 100%Normally on the males the wattles are more cupped forward and the hens they are flatter. Also the helmet on the males should be bigger but that doesn't hold 100% true.
The best way that is just about 100% is feel the distance beween the pelvic bones. Hold the guinea and run your hand down the breast bone towards the tail, once you get to the end of the breast bone keep going until you get to the pelvic bones. The males will be close together about 1 finger width apart and the females much wider, which when you think about it - they have to be to pass the eggs. You may have to go thru a few birds to really get a feel for them but once you do it soooo easy to tell after that.
Steve in NC