My son found an abandoned baby bird. He made it a nest and tried to feed it. I'm not sure how long ago he discovered this. But I just found out. What should I do immediately??

We need more information. Does the bird have feathers yet, are the eyes open. Need to keep it warm. Feeding depends on age. Do not give water.

Call them , leave a message and someone will for sure call you back tomorrow sometime during normal business hours. They are great people and they really know animal wildlife. Please answer when they call back, and they will tell you everything you need to know about your situation.