We picked up a feral baby bird that fell from his nest and took him home to feed, hoping that we can raise it until he reaches adulthood and then let him fly free. Unfortunately, this morning when we picked him up he died
Here’s some details:
My girlfriend and I went for a stroll at a nearby park and our dog found the bird. He seemed to have fell of one of the really tall trees (all bout 10m +) and can’t get back up to his nest. So we decided to take him home since there trees are way too high for us to get up (and there are also so many of them) and there are a lot of feral cats around (bad kittehs!!).
The bird is a generic bird you see around your house. He’s not a sparrow nor a crow, but he’s smaller than crow, black feathers and orange beak.
We took him home and then set up a simple home for him. It was late so we couldn’t get proper bird supplies. Therefore, we took a good sized cardboard box, and covered it with some netting so the bird can’t get out, and filled the bottom with a wrapped tower and shredded some tissue paper for warmth.
The next day the bird seems fine. My girlfriend tried to feed him but he was really scared and won’t eat, so then she kind of gave up the thought and tried to let him go. When the bird was outside, he freaked out a bit and thought “oh nos!! freedom burns!!!” and went back to my girlfriend – then she took him back to his box nest.
That day we didn’t have time to to proper research and go to a local pet store to purchase bird food. So we found some fish food, pre-soaked in water to soften up the pallets, with some defrosted blood worms (couldn’t find earthworms at the time), and gave to the bird – he seemed to like it quite a lot. He was fed this for 2 days.
The next morning the bird didn’t chirp – we went to have a look and he died 
We found him tucked in the corner of the box and just lies there
Can someone tell us what happened to our birdie? What killed it, is it the fish food? Did he died of home-sick and a broken heart? Or could it be he was suffering from the injury when he fell?
Thanks in advance for all your advice