When a hen (female bird) is ready to incubate her eggs after laying them.
This is a normal behavior for a female bird, which is capable of laying and incubating eggs whether she has a mate or not. Eggs laid without the presence of a mate are infertile.
Leave the eggs with her until she loses interest and stops sitting on them. If you remove them before that, she might continue to lay eggs to replace the ones you have taken away. Otherwise, if the bird is in good health and consuming an excellent diet, there is nothing you need to do. If she is not eating a good diet (such as nothing but seed), then egg laying can become life-threatening and the bird should be seen by an experienced avian (bird) veterinarian immediately.
Disclaimer: BirdChannel.com’s Bird Behavior Index is intended for educational purposes only. It is not meant to replace the expertise and experience of a professional veterinarian. Do not use the information presented here to make decisions about your bird’s health if you suspect your pet is sick. If your pet is showing signs of illness or you notice changes in your bird’s behavior, take your pet to the nearest veterinarian or an emergency pet clinic as soon as possible.