In the past week I've lost 3 birds for unknown causes. At the beginning of the year I had 28 chickens, I'm down to 21. I have 3 cockerels (yes way too many, I know). I've lost 2 cockerels, and 5 hens. They were all young birds (all hatched out in 2009 or 2008). All of them were crossbred. About 3 were found outside. 1 hen and 2 cockerels were found outside, 2 of them in the same place at different times.
Most of them were related, either siblings, or because they share the same father. About 2 or 3 were not related in any way.
The chickens I have lost haven't been as precious as others are at the moment, but still a huge blow to me
So;
1) Do you think the deaths were caused by the cockerels, and do you think it is time to say 'goodbye' to them?
2) Is it a contagious disease, and the older birds have grown immune to it?
3) What shall I do?
I know that you have to be prepared for deaths of your pets, but in this huge amount seems suspicious.
Thanks.
Most of them were related, either siblings, or because they share the same father. About 2 or 3 were not related in any way.
The chickens I have lost haven't been as precious as others are at the moment, but still a huge blow to me

So;
1) Do you think the deaths were caused by the cockerels, and do you think it is time to say 'goodbye' to them?
2) Is it a contagious disease, and the older birds have grown immune to it?
3) What shall I do?
I know that you have to be prepared for deaths of your pets, but in this huge amount seems suspicious.

Thanks.