So I fell prey to the temptation of the TSC display. I now have two 3-week-old yellow ducklings. I have no clue of gender or breed as they were labeled "Assorted" & Unsexed. In the last couple of days, one has started making a quack-ish noise in addition to the peeping while the other only peeps. Is this a clue as to gender? Any other tips on figuring out whether they are male or female? Thanks!