why does a bird cant talk sometimes?

An outstanding talent of birds is the ability to communicate by means of calls and songs. Birds sing mainly in the early morning and at sunset, and for good reason. There is less wind and background noise at those times. Researchers have discovered that the songs of birds carry up to 20 times better in the morning and in the evening than they do in the middle of the day. While males are most often the singers, both males and females utter a variety of calls, or short bursts of sound, that have distinct meanings.