There are four chambers in a bird's heart: the left atrium, the right atrium, the left ventricle, and the right ventricle--just like in a human. Most warm blooded animals (birds and mammals) have this cardiovascular system setup in their hearts. If it interests you, the respiratory systemic anatomy is completely different in a bird than in a human. But in short, to again answer your question, there are four chambers in the heart of a bird.
Go to this website to find out more:http://www.earthlife.net/birds/blood.html
--Answerguy555