|MadSci Network: Zoology|
At an early stage of development the baby's heart will start beating so you might be able to detect the embryonic heartbeat. Perhaps a stethescope might be useful for this. Another way of detecting growth would be to hold the egg in front of a bright light and look to see if the yolk sac is getting smaller. As the bird develops the nutrients in the yolk are used up, causing the yolk to shrink. As far as any movement is concerned the young bird would be pretty far along (perhaps a week to a few days before hatching) before any detectable movement would occur.
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