In most species only the male sings, and he's singing for two primary reasons: to attract a female and to warn other males to keep off his turf. Birdsong is related directly to courtship, breeding, and territoriality; this is why we hear birds singing in spring and summer, and not so much in fall and winter.

Do birds sing when they are happy?

Birds will defend the territory around their nests by singing to signal their presence and by chasing other birds away. Birds don't sing to make us happy, they sing to attract a mate and defend their territory.

Why do birds sing to humans?

They sing to attract mates, defend territories, and communicate with each other. They sing not for us — but themselves. Regardless, there are many scientific and anecdotal accounts of how birdsong can positively impact human health. Western meadowlark in California photo by author.