I have a flock of Marans: 6 Black Coppers, 1 Black, 1 Splash , 1 white and 1 Wheaten. I also have 1 Black Isbar. Since New Years Day, the hens have laid eggs despite the cold weather here in New England. Strangely, one of the hens have been laying eggs about the size of a robin's egg and I have collected 4 of these. The Isbar also laid a tiny egg and has not laid another since. Any ideas as to why this is happening?