A freshly hatched clutch of duck or chick eggs is full of cuteness. Unfortunately, it's also full of unidentifiable cuteness and it can be difficult to tell the babies apart. While this may seem trivial at first blush, it's important that a bird keeper is able to identify hatchlings. Proper identification makes it easier to track growth and health as well as separate any birds that are fighting.
Pick up each bird, gently. While speaking softly and giving the baby a treat, touch the bird's feet. Doing this several times a day will ensure that your ducklings or chicks are not afraid of having their feet touched, and the best form of identification for hatchlings requires that you are able to touch their feet.
Paint each chick or duckling's nails a different color. You only need to paint one toe on each foot for identification. Painting only one toe also cuts down on the time you have to spend on a squirmy baby's foot.
Blow on the nail polish till it is dry. It is vitally important that your hatchling is not allowed to ingest any polish.
Use permanent markers as an alternative. Some hatchlings may be very frightened by having their feet touched, even with good socialization. And some owners are concerned about the risks of a baby ingesting polish that is not completely dry. Use the same procedure listed above. Permanent marker may wear off over time, so you should reapply as necessary.