Aww, that was an amazing this to do. I'm not sure about what it died from but I did read an interesting article about adult blue jays. When a baby is out of the nest for any reason at all, that's it, they completely cut ties with the poor little thing. Maybe it landed on something really hard that would cause blood around the eyes or perhaps it narrowly escaped an attack of some kind or it was simply dehydrated and starving. These things are always upsetting when you try so hard to save an innocent little life and I truly commend you for your effort. Maybe call an exotic pet/bird store and ask what they think. I caught my cat eating something in the backyard and when I went out to check there was only the head of a baby bird. I was so mad at that cat but unfortunately that's their nature. I hope you find an answer!

Thanks for the nice words. I did more research and I'm almost certain it was head trauma and he had brain swelling. He most likely fell from his nest onto the concrete that was right next to the tree he was in. Very sad.

And before I get any hate comments, yes, the bird seemed sick/injured when I decided to intervene, and it was too late at night to get it medical attention. My friend had been monitoring this baby blue jay all day after she found him on the ground, and they put it near the parents and in the bushes, but they completely ignored it for 12 hours. I came by to pick it up, since it was night now, and I had planned on calling an exotic vet the next morning to see if they'd take it in. I got it home and tried feeding it soaked cat food, but the poor thing could barely hold its head up. It was barely able to perch, and was extremely clumsy, however it was fully feathered. I thought it may be a fledgling, but it was incredibly weak before so that's why I didn't feel comfortable leaving him.

I had him under a low setting heat mat inside a box with a wrapped up t shirt temporarily, and kept him in a quiet room. I tried feeding him once more, but when I went to get him, he was super weak. His head just kept falling. Unfortunately he died a few minutes ago.

Upon further examination, I saw crusted blood around his eyes as if something had pecked him or scratched it. I thought he had a broken neck (explains the neck hanging) but I think it may have been a brain injury. Would that explain the neck hanging, the wobbliness, and the blood around his eyes? I'm only asking this for future notice, in case I run into a similar case. Dang, I feel so bad, but there was nothing more to do. :(