I have several from supposedly broody breeds & they're the ones I have to watch: 1 Aracauna, 1 Barred Rock & 2 Wyandotte Bantams. As soon as the weather started warming up the Aracauna & both Bantams sat. At present they are being fairly easily dissuaded, thank goodness!I have seen it be “contagious” in my flock, but not to that extent.