The chickens squat because that is what they do when there is a rooster there to fertilize. That shows that they are ready or near ready from what I have heard. The best way to figure out who is laying is to catch them in the act. You have to check periodically when you see one of them go in, stay a while and come out. if there is more than one egg, the egg that is warmer will be the one you catch leaving. Then label them and keep them in a seperate carton so you can compare. My Salmon faverolle lays pale small eggs, my Deleware lays the same colored egg but larger. The double yolkers will throw you off. Ours are massive and occur about every four or five days. Sometimes we have a chicken lay more than one egg a day.