What was Peter's job, exactly?

I was rewatching S2 and got to the bird-in-corpse-in-horse case. There's a scene where Jack and Will investigate Peter in a shack filled with...cages? There's a dog. There's probably a ton of birds, from the noise. There's a fucking monkey. Where was Peter getting all these animals? What's he doing with them? Also, the cages look tiny and uncomfortable, which doesn't fit with his animal-loving persona.