Help! What is this?

[HippieChik]

My son got chicks at Tractor Supply. And after having them home for one day they have this but just mostly on their bellies. He said they weren’t like that when they bought them. It’s only been a day! Any ideas?
He did also say they found the waterer leaking which meant they were laying in damp bedding. Could that be it?

 

[Auntiejessi3]

My son got chicks at Tractor Supply. And after having them home for one day they have this but just mostly on their bellies. He said they weren’t like that when they bought them. It’s only been a day! Any ideas?
He did also say they found the waterer leaking which meant they were laying in damp bedding. Could that be it?

Do you have electrolytes in their water? That may explain the brownish color.