Introduction to death

When I became a parent no one gave me an instruction manual on how to be one. If I were to write one I think one of the chapters, titled something catchy like "Death", would instruct us on how to help your child deal with it. My oldest son, 8 years old, has lost loved ones, and pets, and attended their funerals. He has proven to have a very eerie sense of dealing with death, however today he is falling apart. We are the proud owners of chickens--you know to teach children responsibility and knowing that our eggs are hormone free, etc. etc. One of them was a banty hen (a small breed) she was named Henrietta, after the chicken on Return to Oz. Dax named her, trained her to come to her name, and spoiled her so badly that she would not eat with the other chickens, she needed her own pile of scratch. We had a terrible storm last night and temperatures dipped lower than they have been for some time. This in addition to Henrietta being over 3 years old which exceeds chickens life spans (or so I've been told)--I found Henrietta in full rigor this afternoon and had to let Dax know before he went out calling for the filthy little bird. HE'S A MESS!! We had to put a dog down last summer, we lost uncles and grandfathers in the past year but the child is having an emotional breakdown over a bird who didn't even lay eggs large enough to eat. As I type, he is talking about how she was picked on by the other chickens and how she didn't have a fair life. How do I deal with this? I'm not cold-hearted but my god, it was a chicken. It lived at the back of our lot in a shed. I hate to see my child in so much pain but I'm grasping at straws with this one. Hopefully CAL Ranch or IFA will have banty chicks this spring, buying new has always cheered me up :)