Why do birds sing only in the morning?

Although there are many thought on this subject, some scientists believe that birds sing in the morning because the males have low energy reserves, and are broadcasting to the females that they are fit to breed. Another thought is that the light source isn't strong enough for them to forage for food, and so they sing. Finally, mornings usually bring quietness in the surrounding air, with little wind, and it's though that the sound can travel longer distances, therefore maximizing the ability to attract a mate.

birds do not sing just in the morning but they sing all the time. how you can tell is go outside and sit in a chair close your eyes and listen. it is music to your ears. i personally think in the morning they all greet the beginning of a new day and are sayin "howdy" to the other birds. i dont know the technical answer. its their way of communication. if you listen hard enough and watch close enough you can even tell their warning cries to other birds if there is a preditor about, or their mating calls. set up a few bird feeders and houses and take notes. they all have their own little personalities and sometimes are quite comical. hope this helps

According to Science News, they sing in the morning and at dusk to "attract mates and defend their territories" This article also says that the bigger their eyes, the earlier they start singing.

They DON'T sing only in the morning - at least not where I live. Mockingbirds will sing all the time just to let other mockingbirds know where their territorial boundaries are.

They don't, where i live, for some reason, birds will start singing at about 11 oclock at night, and we don't have excessive amounts of street lamps either.

they don't sing only in the morning, I hear them singing all day long...although they do seem to be most active in the early morning and just before dusk.

They are probably glad to make it through another night and wake up breathing....like me :)

night time they cant see the music sheets

They are trying to tell you it's time to refill their feeders.