Well, being a zoo keeper is definetely a labor of love. I can tell you that with few exceptions you will not be paid well. Fortunately I work for a zoo in Chicago and we get paid fairly well - but considering the cost of living in Chicago the pay isn't that great. Also, we are union keepers [SEIU Local 73], so that helps out somewhat in the wages department and job security to a certain extent. However, many zoos are non-union and wages can be very low.
As an example I saw an advertisement for employment at a facility in Kentucky that works with many very dangerous venomous species. They were looking for a full-time keeper to work with the animals on a daily basis for $8.00/hr. I'm not sure how far that goes in Kentucky, but having worked in Chicago for about that wage before going to work for the zoo, I can tell you around her it gets you pretty much at the poverty level.
Now, with all the dire money stuff explained, I'd have to say that I'm not the sole supporter in my house - my fiance works full-time as well, although she makes a lot less than I do per month - but, overall we live fairly comfortably. As for how one gets into being a zoo keeper, it starts mostly with an educational background heavy in life sciences. Biology or Zoology if you're lucky enough to find a university with a zoo major.
Again though, many of the courses you'd take in a Bio or Zoo degree have little bearing on what you do as a zoo keeper. Just as important as the education is some kind of verifiable professional experience, be it as an intern at a zoo, or vet hospital, university research lab, etc. Basically anywhere that you can get hands-on experience working directly with exotics will go a long ways towards getting your foot in the door at a zoo.
Some zoos may be harder to get into than others. What will set you apart is going to be those herp/exotics-related experiences, or a demonstrated area of expertise. For me, what set me apart and got me hired was 25 years of experience keeping herps but more than that was a diverse academic background, some magazine articles I had written, and my experience in designing and building my own naturalistic vivaria.
All in all, I find my job very rewarding, even on its most tedious and nerve-wracking days. I wouldn't trade my career for any other job I've worked. I'm also a realist to in that I know if end up leaving my current position and go to work at another zoo, chances are I won't be paid as well. Hopefully, the cost of living will be lower [it sure can't be much higher], and so a lower wage won't hurt as much. Still, I love what I do and I'd rather love what I do and get paid less than hate what I do and get paid more.
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Matt Campbell
25 years herp keeping experience
Full-time zookeeper
Personal collection - 21 snakes (9 genera), 20 lizards (4 genera), 6 chelonians (2 genera)