This is my 2nd mix chick order. All other chicks arrive ok except the Partridge Rocks. Two separate orders....One is dead on arrival the 2nd dies within a few hours. I have the 2nd order with one dead in the box and the 2nd struggling chick downstairs. I am scratching this up to something genetic...have not lost any other chicks. What do you think? So far 4 Partridges, no survivors.