I think the hardest part of raising chicks, and even started birds or adults, is that some simply don't make it. It is a reality of poultry keeping. Sometimes we can figure out, or think we have, what happened, and sometimes they just die for reasons we can't determine. I recently had the smallest Speckled Sussex in our laying flock die - just found her dead in the coop one day. We called her Runt, but honestly, by the time they were about 4 months old they were close enough in size that it was hard to tell which was which, except that she had a slightly wry tail. She foraged, dove into her food, competed for apple pieces every afternoon, but a day before I found her dead I picked her up and noticed she felt lighter than her sisters. I made a mental note to pay closer attention to how much she was eating when they all came down the ramp in the morning the next time I was here after sunup, and the next day she was dead. She had no other obvious sign of anything being wrong - I could not detect a stuck egg, no trauma, no parasites, she just died. The others seem fine. This happened before the new chicks arrived, so it wasn't a contamination issue.
I will note I have read elsewhere on this site and others, that there are keepers of many years who say they have never lost birds in this way. Whether this is unusually good fortune, a superior eye for sending less than perfect birds to freezer camp ahead of their natural demise, or the unrevealed exception to the statement, the common experience among poultry keepers is that occasionally we lose chicks and birds, and we don't like it, and sometimes it makes us wonder whether we really want to be poultry keepers after all, and there is no wrong answer to that question. The answer is very specific to the individual and those with whom one shares a home.
I say this now only because we are starting chick season, we have seen losses among those of us who have chicks already, and it's kind of a reality check for some. Whether raised by us or others, some chicks are not going to live to adulthood. It is rarely 100% the fault of the raiser. We do what we can to support healthy growth and hope for the best. New ideas come up here all the time that may make the difference for chicks that are teetering on the edge, but for the most part they are darned stout. Yesterday I picked up a white leghorn chick and the growth she shows in 6 days is phenomenal - and that is typical for most chicks.
So I would like to leave you with this: it is natural to regret losses, and it's fine to go over what you think you did right and wrong, but unless you intentionally failed to supply warmth, food, and water, don't spend time blaming yourself. Learn and move forward. If the losses are more than you can bear, maybe you aren't meant to be a chicken keeper after all, and that's fine too. You have learned something new about yourself.
All of life is learning.
