yep, on waterfowl, It's easy, there are sticky thread in the duck section about it, but for chicks....it's nearly impossible.. takes loads of training and a magnifying glass to accomplish. This is why, outside of waterfowl, most chicks are sold as straight run. Quite a few large fowl breeds can be color or feather sexed, females feather out quicker and are usually born with the tips of the fight feathers already coming in, where males will be just pin feathered. after day 1 though, this technique is hard to do as the males will start to open up by then. And it is breed dependant as well.