Sorry the PEN was the Pen the birds are in. I mark the eggs with pencil. The marans eggs I mark with an artist pencil that is white. The vet wrap can stay on for a long time.... months. After they get to be about 3 months, I use velcro and use pipe cleaners for the color markers. I can't put up a pic right now, if I can remember I will later.
The vet wrap goes around the leg? The pipe cleaners on top of the wrap if you need another color? Wow! I'm going to try that. Thanks!