Most of the professional herpetologists I know are not herpetologists full time. Unless there is the opportunity to work with threatened or endangered herps on a long-term (usually funded) project (and most often concerned with amphibians these days), or the lucky landing at a zoo's reptile house, or you're a professional breeder, most career choices involve knowledge incorporating the other sciences (fisheries, wildlife, forestry, etc.).

There is often confusion as to who earns the right to be called a herpetologist. Many believe that because they've been breeding all kinds of herps for years on end, that they consider themselves herpetologists. At present I only call myself a herpetology student (even when I graduate, at heart I know I will ever remain the student, for the beauty and mystery the herp world has to give us just keeps on giving!
I believe if ya throw an "ologist" in your title, you need to at least have a Bachelor's Degree in a natural science. I don't believe herpetology is at the Bachelor's level, however there are rare circumstances where you can have a Zoology major modified into a Herp major, but only with extreme scrutiny and final approval from the department of the major. I know of one local woman doing this (California Reptorium).
For those who would contest that a degree is required for the herpetologist title, I believe just because you have had years of experience with herps (and you may know your stuff!), doesn't mean you necessarily know the process of the bigger picture. I don't mean to offend; I am just saying that a well rounded scientific curriculum ultimately walks it likes it talks it. Whether I choose Wildlife, Conservation Biology, Natural Resources Interpretation, or Zoology - I have to know and appreciate Statistics, Calculus, Biology, Botany, Chemistry, and a whole plethora of classes specific to the major... as well as take some elective science classes (i.e. Mammology, Dendrology, Soils, Geography, GIS, etc.) That's the bigger picture! I'd love to hear other's perceptions regarding this.

Of course I do have to pay tribute to the locality "experts" found the world around. Nothing beats that gestalt recognition of a wild species like that resulting from the quick reactions of a local herper on his or her favorite grounds!