I think it literally means responding to his own kind. While Sirius isn’t a werewolf in the traditional sense, he is a were (man) wolf (dog). In fact, I would imagine any Animagus that takes a dog/wolf form would, to a werewolf, be considered “its own kind”. The only difference is that Animagi change at will instead of during the full moon.

It just means he responds to wolf howls. He even responded to Hermione’s fake wolf howl.

In the book, Hermione did not howl. And even in the movie, the howl from this screenshot is his initial howl after transforming; he did not respond to Hermione’s (film) howl, and I think the “response” part of this description is an important distinction.

I think the thing about werewolves responding to the calls of their own kind was just from the movie. I don’t remember that being in the book.

@Icecreamdif

I don’t remember that being in the book.

That’s right. It wasn’t in the book.