This beautiful bird is a favorite of many people and is eagerly awaited in the spring after a long winter. In places where bluebird nest boxes are erected and European Starlings and House Sparrows are controlled, up to six pairs of bluebirds will nest on as many acres. In the past 25 years bluebirds have become uncommon in the East for reasons not altogether clear. Competition for nest sites with European Starlings and House Sparrows is likely a critical factor. The erection of many artificial nest boxes in recent years seems to be helping to increase the population. They will lay 4-6 pale blue eggs in a loose cup of grasses and plant stems in natural tree cavities, old woodpecker holes, fence posts, and bird boxes.