There is a bird nest under my balcony and there are three little green eggs?

How long have the eggs been there? It is possible that the mother was spooked away from her nest or she went to take a break for a while. The same thing happened to me. I guess every time that I looked in the nest, there was no mom, but this morning, she was sitting on top of the eggs. Weird, right?

Why do you think the mother abandoned it. Unless you have been watching the nest 24/7, you would really not know if this nest is being cared for. They don't sit on it ALL the time..they leave to feed, go to the bathroom, etc. Just let it be..if the parents are around, soon you will have chicks in the nest. If not..the parents will rebuild elsewhere and try again. It is really not responsibility to do anything with this nest. Also, illegal to interfere. Don't continually approach the nest as you could be the one keeping the parents away as you are considered a predator.

First and foremost do NOT touch the nest. If the mother detects your scent on it she will abandon them. Mother birds don't usually hang around their nests too often (as mentioned above) just leave it alone.

Are you sure its been abondoned? Mother robin's will draw away from nests of they see people close