There is a tenuous moment after you steal the chicks out of the nest and put them in a makeshift nest. The chicks will naturally hunker down and go quiet in the presence of a predator. On the other hand, they jump up, open mouths, and get really loud when the parent arrives with food. After you have first moved them, it is critical that if they jump up and open their mouths you get food in them. Then they learn that you are feeding them, and every time you approach they will cry out for food.
If you screw it up, you can have a chick die of starvation. The intermediate step is to pry their beak open to get food into them, which doesn’t always work.
Raising crows involves environmental theft, stressed animals, and it’s against the law. That said, I make crow nest map every winter. I’m too old to climb anything but a hemlock, but I would recruit a high school kid if I found the right nest.
There is another way to get crows. They grow so big that they are kicked out of the nest before they can fly. That means each spring there are flightless juvenile crows being fed on the ground by their parents. Theoretically, you could catch one on the ground. I have chased such crows, but not come close to catching one. I have considered setting up a have-a-hart trap near nesting sites to see if I could catch a crow, but I doubt it would work. Crows are too smart. I don’t think you could catch one that way.
So, soft-boiled eggs because you are feeding them with a spoon and the trick is to get the food in their mouths quickly. Once they get a little older they will eat anything. You can feed them eggs, hamburger, pieces of fruit, etc. They love grapes.