Some people "paint" a small amount of food-grade NON-TOXIC food coloring on each hen's vent, in order to see who is laying what egg.
I've never tried the food colorings, as I've wondered if would merely come off in different colored poops. LOL! I've always run outside (when I'm home) to see who's just laid. After that, I can tell based on the size, shape, color, texture of the eggshell -- whose it is.
Some people, with more $$, invest in a webcam pointed at the nests. That way, they can remotely see which hen lays, & in what nest, etc.
Other ways to tell which hen(s) are laying eggs:
1. You can fit 3 fingers, (for large breeds) or 2 fingers (for small) between the pubic bones that surround the vent.
2. Squatting easily. The hens that are laying, or near their point of lay, will squat when you reach for them or when you extend your hand over their back.
3. Combs and wattles are very bright CHERRY red.
4. Oyster shell, in a free-choice dish, is being consumed.
