i have 2 four week old scovy ducklings. they are on unmedicated chick starter. i take them out every day to play and hang out with me. i've noticed though that when they're out with me their poop has a very distinct nasty odor and is all watery and is a very dark greenish black color. however after a while it starts to look like normal bird poop (more solid and normal colored). they seem and act completely normal and healthy though. why is this and is it normal? could it be because they're really excited? they do get really excited and happy when i take them out. i just want to make sure this isn't something i should worry or do something about.