They need to have electrolytes and vitamins in their water for a few days, if you haven't already started them. Pedialyte, gatoraade, or homemade electrolyte solution will work. Stress from shipping, especially in cold winter months or the hot months of summer is very hard on them. I'm not sure why they ship chicks in Jan-Feb anyway. Here is a recipe for electrolytes: http://www.the-chicken-chick.com/2012/07/chicken-heat-stress-dehydration-and.html