Green on duckling's breast?

[ritzquacker]

I just got three Magpie ducklings on Friday and I noticed that they have a small ever so light green smudge on their breast. It's definitely not the color of their feathers, as it looks like the green from a marker. Anyone know what this could be from? It didn't come off during their first swim...thanks!

 

[Amiga]

Could it be they were marked from the source of the sale?

 

[Oregon Blues]

Hatcheries sometimes mark ducklings with marking pen, usually for gender. Did you order all females?

If the ducklings came from a breeder, sometimes breeders use marker to differentiate parentage for a few days before they band.