I have two ducklings and until yesterday they were pretty much identical except that one is larger than the other. Then last night I noticed some white at the tips of one of their feathers. The other one doesn't have that. They are about 5 1/2 weeks old now. Does this matter as far as sexing them goes? Does one sex get that white and not the other? These are my first ducks and I'm still dying to know whether I have one of each sex or two of the same. Thanks to anyone that can give me any clues to this mystery. Thanks!