well... you could get a peice a card board and put it in the cage in a corner. so the bird could get alittle privacy.and put something in the middle so the egg wont roll any where.and put food near...
male fighting fish will built the nest for the female to reproduce..after builting the nest,this will attract the female fish to produce the egg inside the bubble..after that,the male will take care...
Depends on what's going on with the birds. If they have eggs or babies, the reason is obvious. If no eggs/babies, some birds like to "hide out" and/or enjoy the comfort and security of enclosed...