No, there are several breeds that do. Marans, Welsummers, Penedesenca, Barnavelder, and there are more.
Who else is waiting for that first egg? - Page 223
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I've read that they lighten up as the year goes along, but mine seem to go up and down, lighter, darker, lighter, darker. I have one that lays a rosy color, the intensity changes, but the basic shade is still different from the rest.
Good luck with your freeloaders. Mine freeloaded for 26 weeks.
Got another lavender orpington egg yesterday! A little darker pink color than her first. I assume it was the same hen. Yeah!
I have 4 of these girls that are about 25 weeks. I think they are barred rocks and would lay brown eggs and been patiently waiting for eggs. Well for three days now I've had an extra white egg so I waited around the coop today to figure out the mystery. And she laid an egg and it was white.