I think the House Sparrows are taking over all my birdhouses this year. The Eastern Bluebirds are putting up a great fight but it’s not looking good.
Note: One of the above photos was taken with the Canon PowerShot SX50 HS. Can you tell which one?
Males take up nesting sites before the breeding season, by frequently calling beside them. Unmated males start nest construction and call particularly frequently to attract females. When a female approaches a male during this period, the male displays by moving up and down while drooping and shivering his wings, pushing up his head, raising and spreading his tail, and showing his bib.
Nest sites are varied, though cavities are preferred. Nests are most frequently built in the eaves and other crevices of houses. Holes in cliffs and banks, or in tree hollows are also used. It sometimes excavates its own nests in sandy banks or rotten branches, but more frequently uses the nests of other birds such as those of swallows in banks and cliffs, and old tree cavity nests. It usually uses deserted nests, though sometimes it usurps active ones. Tree hollows are more commonly used in North America than in Europe, putting the sparrows in competition with bluebirds and other North American cavity nesters, and thereby contributing to their population declines. (Wikipedia)