posted 9 years ago
Impossible to say at this point, but daily observation will help leading up to situations like this, an animal doesn't lose that much body mass overnight, granted with a herd running around its not an easy task. We hand feed our free ranging birds every afternoon just for this purpose, we can count them and look at all of them for problems like this showing up. Also during your rounds watch for individuals showing signs of being sick, they'll generally stay away from the others staying in one location not doing the search and peck routine with their head/neck retracted close to the body, looks very similar to a cold chicken. We had a situation close to yours, we never found the exact cause, but highly suspected it was associated to rats, once we beat the rat numbers down, we stopped having sick/dieing chickens.