In most areas where the Eastern Bluebirds winter in the United States the male beginning in early to mid February takes the female around to potential nesting sites for the two of them to get cozy. First babies are often born the first or second week of March.  By the end of January is the best time to install Bluebird Houses if you are going to put them up. If you can’t do it until later – don’t despair as Eastern Bluebirds often raise 2-3 families per year depending on weather and food availability. Eastern Bluebirds also often use Bluebird Houses as a winter roost to get out of the wind and winter weather.