Well said. Someone familiar with leukosis remarked the symptoms did not really resemble that condition. With no real evidence anymore I've even considered poisonous plants in the environment (lungwort, bindweed, amaryllis) and got rid of them. Frankly I'm tired of guessing. Onward!

The remaining 6 of 11 seem to be fine (knock on wood), the pullets are laying great and will be a year old in July. Next year when they're 2 we hope to try and hatch from the hens. They are heritage types, rare ones, so quality and natural chutzpah is our goal. Between the mystery condition and this bleak, endless winter, they're earning their stripes.