If your degree is a 'general' bio or Environmental Science, I would still try to apply for the masters program of your choice. A lot of universities do not provide specialty majors such as Zoology/Herpetology for undergrad. Thats why there are masters programs for those specific fields. Check out what their requirements are and talk to an academic adviser from your school of interest.
If you are able to do that, don't waste another 4 years for another degree. Although you might have to do so depending on their requirements and past courses you've taken.
Is there an option of transferring whatever course units you have to a 4 year university program and just continuing your schooling there?
Sounds like you still have some time before you get your degree. If you have all the basic pre-reqs and general ed, you might be able to transfer to a university with a major that is more linked to your interest (zoology/herpetology/ecology/etc).