I have been noticing some really yucky looking Black, Tarry-looking poo in the babies run lately. I think it's from the goslings but i'm not for sure. I have also noticed a slight smelly-ness(not like normal duck poo) around the coop/yard in the last few days. Could it be from all the new access to grass & other goodies in the yard? They're all still getting plenty of feed and always have fresh water. They're all still very healthy, normal acting babies too. just cant figure it out, im a little stumpped.