If you are looking to study this formally or deepen your understanding, here are the standard texts:

: Animals interact via four primary modes: auditory (sound), visual (sight), tactile (touch), and chemical (smell/taste). Technological Advancements in Veterinary Practice

Veterinary science has moved behavior out of the realm of philosophy and into the realm of biology. We can now measure stress through cortisol levels in fur, fecal metabolites, and heart rate variability.