OK, I`m gonna simplify the process for egg laying detection. The book 2txmedics quoted may be 100% on all counts, dunno. But what I do know is how to tell if a hen is laying. Pick up the hen and feel the bones UNDER the vent. If you can place 3 fingertips between the bones, the hen is laying...
I suppose it could depend on breed or degree of excitement, but I also believe, from years of observation, that a pullets comb and wattles, along with facial tissue, turns red and stays red with maturity. Variations occure with health, such as worms or illness, but the color comes on just before...