This is an analog electronic chirp generator with a light-sensitive resistor. The chirping sound is created by the circuit that you see inside of the transparent mylar bird. All of the electronic components are discrete (no software or recordings). Note that, sometimes, the bird does not change its song when I cover the photoresistor. That's because I have an LED coupled to it -- so when the LED is turned on at various points during the oscillating cycle, my actions are irrelevant (because the photoresistor "sees" light from the LED).