What are reasons for birds abondoning the nest?

Question

what are some common reasons why the parents would abandon the nest before the eggs are hatched?

Answer 1

If the eggs are not fertile, the parents will eventually figure it out and leave since the eggs are dead and never going to hatch.  They might also abandon a nest that has an excess amount of disturbance near it.

Answer 2

Normally they will do this if the eggs do not hold their body heat. That is one way the parents know the eggs have live babies in them or not. They may also leave the eggs if you interefere with them too much or are trying to handle them. They will also leave them if they have sat on them long enough to hatch and they don't hatch. Usally giving up on them all together.