Recently I noticed one of the two (the presumed female) has been sleepier than the other, plopping down for a nap during outside time while the chicks and other duckling played and explored. I started paying ridiculously close attention for any sign of illness, and I have discovered that she is quite a bit lighter in weight than her presumed-male counterpart. "He" has indeed developed thicker legs than her and seems to be bigger every time I check on the brooder. She eats and drinks and flaps and runs around, but the fact that she is smaller, growing slower and is more prone to naps and yawning has me a little worried!
My question to you wise duck experts is, could at least the weight difference be caused by gender? Is a sleepy three-week-old something to worry about or am I just overreacting? My chicks are always funny about naps when they are that age but somehow I feel like my little ducks are more delicate! (Help me)
Any sage words of advice are much appreciated.
(Chocolate is "male" yellow/white is "female," and the pictures do not illustrate what I'm talking about at all but they're really cute so enjoy)