I'm no professional, but I do have a lot of money invested in camera bodies and lenses. For seven hundred dollars you could struggle to find a decent camera body and quality lens that is long enough to reach out to photograph wildlife. You might consider a camera body/kit that is a couple years old, and spend the remainder of your money on a decent telephoto lens. Some potential models are below.
Nikon D80, Nikon D3100
Canon t1i, Canon t2i
Sony a500, Sony a550
Most of these camera bodies can be found used on ebay, craigslist, etc for around $400. They offer plenty of resolution for the needs of most amateurs. If you really look hard you might find one around $400 with a kit lens included. (Some of the above cameras also shoot HD video)
You could then spend the remaining money in your budget on a decent quality telephoto lens. The lens below comes to mind. It has excellent reviews for optical quality, especially for the price. It is a Tamron 70-300 lens with vibration compensation. The link is for a Nikon mount, but you can get it for Sony and Canon as well. There are cheaper telephoto lenses, but the quality won't be the same.
http://www.bhphotovideo.com/bnh/controller/home?is=REG&sku=728343&Q=&O=&A=details
This is my two cents, others might have additional or differing advice. I hope you find what you are looking for. It is a fun hobby, but does get expensive.
FYI, for $700 you can get newer model cameras with kit lenses. (Nikon D5100, Sony a580, Canon t3i, etc.) You might decide to start out with a new camera and kit lens, and then save up for a decent telephoto lens to be able to reach out to capture wildlife.
So many options....good luck.
