I have 5 Black Australorph chicks that are 10 days old. One of them is half the size of the others. She tends to sleep more than the others. She eats and drinks, and when I pick her up, she cheeps and moves. Is she just a runt, should I be worried
Sometimes runts are just runts and other times they have something internally wrong with them. Those that do will generally pass by 4-6 weeks. Yours sounds like it may have something wrong with it unfortunately. Those that are just runts will act fine but just be smaller.
Sometime runts just need more time. I had a runt this year in a group of chicks I was brooding. She vocalized a lot, got cold very easily, suffered bouts of pasty butt, and for the longest time, I was not very optimistic. Finally, at about 6 weeks she got stronger, but was still much, much smaller then everyone else. Then, somewhere around 3 months, she got a voracious appetite and had a big growth spurt. Now she is 5 months old, and has turned into a normal-sized, beautiful pullet.