I have never heard of this, so I googled a bit. Pigeons hatch their eggs in 17 - 19 eggs, so this might be an issue. Since the instincts tell the pigeon they don't need to site 21 days. Pigeon eggs develop with 98.4 -100.4 degrees so this is different as well. With chicken eggs even a fluctuation of a degree can change the outcome of the hatch. Also I would assume the egg size would be a big factor too and if the pigeon can get the egg/s under them. Interesting thought though. Keep us posted.