you say the eggs just hatched and both parents are now gone overnight? Is this correct? If so it is unusual for atleast one of the parents to not be on the nest...i was thinking however perhaps the parents went to the feeding ground or where ever they go to get something eat/drink and will be back in the a.m. but i raise pigeons in a controled enviroment so i cannot say for certain what happened to the feral pigeons...perhaps they do things differently then my birds do. As for raising the babies yourself i would say they have a very slim chance of survival, if they babies are not kept warm constantly especially right after hatching they will die. It is not until the birds are about 10-12 days old with some feathering stating to show they parents will start to take some breaks from the nest.
thank you for explining.the parents come back.But they are gone now for longer and longer.and i was just afraid that its too long...and didnot know if i should get involved.the nest is very close to a window and they get scared easily by the noise.but they come back.or may be its just one parent.i cant tell