my teils laid an egg

Question
Thank you for your previous advice. After I emailed the question to you I went ahead and put the nest box in the cage. I put the egg in the box with some shredded unprinted newspaper. The male, Jergy has taken to the box quite nicely. He refuses to let me put my hand in the cage now. The Sunny has visited the box too but they don't seem to be sitting on the egg. I would have to wait until they come out of their cage to fly around the room before I can get the egg out again, but should I assume Jergy has turned aggressive because I took the egg out last night and then moved it into the box. Is he being protective towards having the egg and nest box. How does this sound to you? And should I remove the egg again to keep it warm? If so, how do I warm it safely without getting it too warm? This is Sunny's first egg, and it's only been about 18 hrs since she laid this one. She's at a good age though I've owned her for over 14 months and she was several months old when I bought her. I would love to save this egg, especially if it's fertile but more importantly your advice will be most valuable for the eggs she has in the future. Thank you. Mariesa.
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The text above is a follow-up to ...

-----Question-----
I have a pair of cockatiels, Sunny and Jergy. We weren't sure that sunny was a girl until she gave us an egg tonight. What a surprise. It explains all the strange noises they've been making but I still don't know that they mated and I know it is common for females to lay without a mate. So how do I tell if this egg is one I should keep or not. How can I know it's fertile and what do I do with it because the birds are but disinterested in it. I laid it on a scarf and I made a nest box for them is it too late to put the box in the cage? Should I keep the egg warm? I live in Kansas and it's very cold right now. Should I turn up the heat around the birds? Please help me. Mariesa Thank You.
-----Answer-----
Dear Mariesa,
The only way to find out if the egg is fertile is to keep the egg in the Cockatiel's cage and see if they take care of the egg. You should keep the house at 75 degrees Farenhiet. If they do not take care of the egg, you should. Just to be safe do not get rid of the egg, it might be fertile. You should keep the egg warm. If I were you I would keep the egg warm and wait a month and a half to see if the egg will hatch. If this did not help you ask a vet.
Good Luck!
Carly

P.S Could you please rate my answer?


Answer
Dear Mariesa,
The info you are telling me seems very good. If I were you I would not touch the egg. I would leave Sunny and Jergy alone and see how they treat the egg. What the male is doing is a good sign that he is protecting the egg. If the egg hatches (if the egg is fertile) please email me at cmf12@comcast.net!!! I would assume that Jergy has turned aggressive about the egg. If they do not warm the egg, you should not touch it because they might turn very aggressive. Instead, you should keep the house at 75 degrees Farenhiet. If you have any more questions, you can email me.
Good Luck!
CARLY