Hi Manal,
If the eggs are past the due dates by at least a week, then go ahead and throw them away and take down the nest box. Then you can make some changes to discourage more nesting. They might still mate, but mating does not mean she is going to lay eggs. Separating them will just be stressful, and a female cockatiel can get stimulated to lay eggs just by her mate calling to her.
There are some changes you can make that should discourage her from laying eggs again. But if she continues even after you make changes, you may end up having to take her to an Avian Vet for a hormone implant or shots.
You need to do all of these things to discourage egg laying. Keep in mind that to lay eggs, she needs longer daylight, warmer weather, abundant food, and a quiet, private environment. Your goal is to reverse these conditions.
Limit her light to 8-10 hours by covering the cage early each evening
Do not give her anything to use as a nest – no bird huts or tents, no box, bowl, etc. If she decides to sit in a food bowl, remove it and replace with smaller cups.
Do not give her anything to shred such as paper or cardboard.
Rearrange the toys in the cage frequently.
Move the cage to a different place in the room. Move the cage about once a week, or whenever she shows signs of nesting – settling on the cage floor for example.
If she is let out of the cage, do not let her get in any dark cozy places and don’t give her free roam.
When you handle her, limit any petting to her head and neck – do not pet her on the body.
If there is no metal floor grate, then do not use any bedding or paper in the cage tray – leave it bare and clean it daily.
Thank you for asking Lafeber,
Brenda
