Do you have any idea why? The first batch I hatched this month are so friendly it's bizarre. They run up to my hand and want to be petted. They cry for me when I'm not there. I've NEVER had chicks like this before. I feel like it might be because I helped them hatch, talked to them and had my face constantly in the incubator window when they were drying off. Maybe they imprinted in me?
I also have two batches of chicks with broody hens. One hen sees me as an ally and friend. The chicks are not necessarily friendly, but they aren't afraid of me and will take food from me. The second hen doesn't like me at and has taught her chicks to fear me. When I enter her coop she tells them to stay clear and they do. She doesn't allow them to eat the food I bring until I'm gone. These two groups of chicks are all from the same eggs, but their moms have raised them completely differently and it shows.
Yup, it's because of bonding! My older chicks (that I rehomed, I miss them!) I handled from day 1. I was always cooing at them, picking them up, feeding them from my hand, etc. They were in my basement where I spend a LOT of time, so I was pretty much with them 24/7. They at least saw me a lot. I mean, I'm sure I'm overstating how much time I spent with them, but you get the idea.
The other chicks were much smaller, and my older chicks wanted to pound them. So they were in a smaller brooder in the back of my larger brooder. As a result I couldn't get to them as often. I'd feed them, but I didn't have time to coo at them since the older chicks wanted food. By the time I rehomed my older chicks and moved the Tinier Babies into the bigger brooder they were about two weeks old and happy on their own.
Weirdly, two of my Tiny Babies (the older batch) were NOT friendly at all. One was terrified of me, the other bonded with the one who was terrified of me and followed them. My older babies would come for worms and crawl all over me. They ALWAYS followed me and came when I called. These guys come when I call about half the time, and have no interest in following me unless it's outside.
I personally think not having a rooster (roosters seem more willing to be friendly) isn't helping. My rooster was the leader and always taught them what to do. He had no shame.