The female Eastern Bluebird lays a clutch of around 3-5 light blue eggs. Vary rarely will a bluebird lay less than 3 eggs, or more than 7. Not all Eastern Bluebird eggs are blue. As a matter of fact around 7% of their eggs are white, and I have found many that are grayish. The color variations have nothing to do with the size of the egg, fertility, or how the fledgling turns out. The female is the main incubator of the eggs, and will usually lay one egg each day before noon. She will start to incubate when all the eggs are laid. Once she begins incubation it takes around two weeks (14-16 days) before the eggs hatch at an average temperature of 96 degrees.