pigeons cooing

Pigeon question?
Druign this week, 2 pigeons have made a nest outside my balcony. However the past 2 days they were not in the nest, but just today in the morning when i checked, they were there and i saw them rotating to sit on the nest. So from this, i guessed that there were eggs. However, just about 1 hr ago when i checked the nest from my window, the nest was epmty with no eggs and the pigeons werent even there. Why is this? I even saw the male pigeon cooing to the female pigeon for her to move and for him to sit cuz i saw them rotate, but then a few hrs later, no birds on nest, no eggs either… hmmm can any1 clarify why this may be? I wud like for them to lay eggs, but this is kinda weird what is happening and all. Thnx for any1 who can clarify this to me/explain to me.
Hi there, I think i can explain some of the cause of this, the egg that the pigeons set there was either moved or eaten, i have also read that birds can carry there eggs fair distances if they are extremely dissatisfied with their current nesting place, also the nest was likely pretty light without the egg so I think i can piece together what these pigeons did, they were two lovebirds that found each other to be the right parent for their child, so the eagerly set off to find a nesting place, they may have tried a few other places on their way, the birds may have noticed you lived close to their nest and took off, one carrying the egg, it is probable that they will do this many times while waiting for their egg to hatch, although some birds are happy to nest near humans because they have learned that a lot of human houses will keep off other predators, but these pigeons my have had some suspicions and just wanted to take off, i hope my answer will be helpful.
Ah yes, one last note, if that egg was eaten the pigeons would share in their sadness then leave, since there is no other reason to keep living there.
Wonga Pigeon cooing