Prusten

My question isn't quite as philosophical as the others thus far, but I'd really like to know everyone's opinion concerning it. On page 163 Pi describes Richard Parker making a peculiar noise called Prusten. This noise is kind of like waving a white flag. It proclaims that the tiger means you no harm. Why do you think he made this noise to Pi? This was before Pi started taking care of the tiger in an attempt at taming him. Is it maybe because Pi did something to assert himself as alpha male unintentionally? Was it that the tiger was use to humans taking on this role since it had grown up in a zoo? Or was it that the tiger recognized the danger of their situation and didn't want to be left all alone?