It's a little Laurell-speak. Laurell Hamilton, the author.
In the series I've finished reading (There are twelve books), one thread that continues to build is the main character's (Anita Blake's) relationship to the community of wereanimals. It has a lot to do with her personal relationships, but also coming to terms with the powers she has.
There are however several scenes in which there is a pecking order that comes apparent. Scenes where there are wereswans and wererats and wherewolves in the same vehicle in various states between human and animal.
To the werewolves, the wereswans are alluring—because of bloodlust. Because swans are food to wolves.
Through her writing, Laurel describes the innate, subconscious knowledge that the wereanimals have. The swans are much more physically slight and are effectively useless in any sort of physical confrontation or conflict. The swans "know" they are prey. They broadcast their unease in certain circumstances with body language. The wolves, with their strength and cunning and teeth and claws are not afraid.
When I spoke of prey ealier, I intended to describe my notice for the first time of an unconscious knowledge. The slight, attractive woman who was so obsequious as she was trying to get around me. And I am 6'2" and 225. Not massive but I stand out.
I had a very brief but primal moment when I knew intuitively that I could overpower her physically, perhaps easily. And there would be little she could have done about it.
And it made me understand Laurell's writing a little more, and it made me understand why woman some are so uncomfortable alone with men.
Making the thoughts conscious and understanding them was a little shocking, but it was a powerful sensation that I will remember.
Inwardly, I have to say I was amused.

that's why they are called 'wolf whistles.' :) The "lecherous male" is considered a wolf in our society, preying on women. Little Red Riding Hood was originally much...sexier than we know it today. I prefer the visceral version, personally.
There have been times when I've had the same flash of primal knowledge, something dredged from deep in my instincts poking up through all my socialization. I found the sensation frightening the first time. It came with an afterthought of, "Oh dear. Is this it? Am I finally starting to truly lose my mind? Will they be tracking me on America's Most Wanted soon?"
I understand when I catch a predatory glint in a stranger's eye, and more than once I've held my breath, waiting for his self-control to kick in, and trying to blend into the background like a fawn in the forest.
I finally started Lunatic Cafe tonight. The tension between Richard and Jean-Claude is akin to that predatorial pre-fight feeling.