Anyone have a bird????

[AngieDoogles]

My mom is out of town. She went to the beach with my brother and sister and a family from her church. While she has been gone, I have been taking care of her dog Chipper and her cockatiel Sonny. We have had Sonny for six or seven years now. (I say "we" because I was only 14 or 15 when we got him so he still feels like mine.) Anyway, tonight I went to check his water and food and he starts going crazy. He was hissing at me and making all kinds of really crazy noises. I was a little worried, but I continued to change his seeds. As I was about to put his seeds back, I noticed something unusual at the bottom of the cage. It was an EGG! Apparently, HE is actually a SHE. I flipped out a little because I didn't know female birds could lay unfertilized eggs and I KNEW that she had not been in contact with any other birds. I felt pretty stupid when I looked it up online and apparently it is pretty common. Did any of you know this could happen??

Anyway, now we are watching HER even more closely to make sure that she doesn't lay eggs every few days because apparently the "motherly instincts" can make that happen. If you have a bird, any advice??