Expert: Miguel Rodriguez - 3/21/2010

Question
Do Robins have a belly full of eggs that they lay all at one time or do they just produce one egg a day or so till their nest is full?

Answer
Most of the smaller birds don't have their eggs develop all at the same time inside the reproductive tract. More so in several species where the female is promiscuous and may mate with several males during the course of several days. Thus, of the whole clutch, all eggs could come from several fertilizations of several different days, and laying may span several days. In a lot of species, usually only the chick from the first-laid egg will survive.