Their poop can be a little funky until their digestive systems are in good working order, shouldn't take more than a couple few days. A chick that is not eating and drinking well can have the problem, excessive heat or cold, internal genetic deformity, the wrong foods... all can stymie the digestive system.So what does cause pasty butt? I had this issue with the last 10 hens I bought from a hatchery. We were able to clean the areas and never lost a chick.