Is there anything else that affects bond prices other than the federal reserve?

[Mike]

I understand that when the feds raise interest rates, existing bond prices fall in order to adjust to the new yield, and vice versa. However, the feds seemed to have only been lowering interest rates this past year and the fed funds rate appears to be in the all time lows, but the treasury bond yields have been rising since October. What is causing this? Thanks in advance.