Abird sitting in a tree flies away as you walk by. which of the life characteristics explains the bird behavior

The bird has a brain right ?
So that means it has nerves so it's natural instinct is to flea beacause its afraid of you

All subjects. the MAIN difference between a rain forest and a desert ... type of liquid silicon rubber or silicon oil can be easily and transparently and not so expensive used for fill the many glass chambers each with dimensions of 50×30×3 cm ... 4 liter space volume (each one) so quite stiff and tightly stick to it's glass ...