Question

How pir sensor differentiate whether animal is detected or bird is detected?

Answer 1

PIR sensors allow you to sense motion, almost always used to detect whether a human has moved in or out of the sensors range. They are small, inexpensive, low-power, easy to use and don't wear out. ... They are often referred to as PIR, "Passive Infrared", "Pyroelectric", or "IR motion" sensors.