Birds have kidneys, just like people do. The biochemistry differs somewhat (birds produce uric acid and urates rather than urea), but it's the same kind of organ and does more or less the same thing.
For waste filtering, the kidneys. The liver filters blood, too, but not of wastes.
the urinary system filters waste from blood
The kidney filters the blood of the frog.
Kidneys filter blood and remove waste.
your lungs
Kidney filters waste from blood in human.Kidneykidneys
urinary system
the kidney is the major organ that filters the waste blood
A sieve.
urine and wacth
Kidneys
filters the blood of waste